The Guardian™ recorder contains dangerous voltage levels during operation. Do not disassemble the recorder. THERE ARE NO USER SERVICEABLE PARTS INSIDE. Do not install or operate near open bodies of water. The Guardian™ is intended for use with a standard 2S meter base, with the appropriate revenue meter plugged into the meter base. Wear protective gloves and safety glasses at all times during installation and operation of the Guardian™. If possible, disconnect power during installation. If the green ground clip is damaged or detached, call PMI for a replacement. Do not install the Guardian™ if the green ground clip cannot be attached to earth ground. When removing an installed Guardian™, always completely remove the revenue meter before attempting to remove the recorder from the meter socket. The USB port is electrically isolated from the 120VAC line. However, to ensure user safety and prevent damage to the unit, plug only the supplied Guardian™ USB cable into this port. Plug the other end of the communications cable into a USB port. The Guardian™ contains a lithium battery for memory backup and a nickel metal-hydride battery for battery ride-through. These batteries are not user-replaceable. Follow all applicable regulations concerning disposal of batteries if the Guardian™ is discarded, or return the unit to the factory for disposal. Although the Guardian™ has been designed and built to be as safe as possible, great care should be exercised at all times during operation and installation. Follow the National Electric Code as well as any local safety procedures at all times. SIGNAL INPUTS WARNING Use extreme caution when wiring signal input connections. Hazardous potentials may exist on signal input terminals, which are floating, with respect to instrument ground. These hazardous potentials may be exposed inside the instrument case and on the Connectors of your instrument. Any voltage potential at the signal source will exist on the instrument s respective signal input cable. Contents of the Guardian™ Package The Guardian™ has been packaged with the following items: Guardian™ meter socket recorder CD-ROM containing latest versions of ProVision™ software, WinScan™, and all documentation USB communications cable A sealing ring to secure recorder to a meter base If any of these items are missing, please call PMI immediately at 1 (800) 296-4120. The CDROM includes the latest version of ProVision™, WinScan™, example data files, and documentation for the software and all PMI power analyzers in Adobe Acrobat® format, Acrobat Reader®, and the latest firmware for all PMI power analyzers. Introduction Power Monitors Incorporated (PMI), an industry-leading product design and manufacturing firm based in Mt. Crawford, Virginia, specializes in applying advanced technologies to develop stateof-the-art power quality monitoring solutions for residential, commercial, retail, institutional, industrial, and substation applications. Since 1987, we have worked directly with electrical utilities and their customers to identify and address a wide array of power quality concerns. We pride ourselves in delivering leading-edge power analyzers and software that are as easy to use as they are affordable. Our 24/7 technical support is consistently rated "best in the business." Dedicating ourselves to this high standard of quality, we have developed the Guardian™ meter socket power analyzer. The Guardian™ combines the powerful, technologically-advanced analysis capabilities of our other power analyzers with the specific needs of single-phase meter base applications. We developed the Guardian™ meter socket power analyzer specifically to diagnose and record power quality issues at the revenue meter. The unit plugs into any standard 2S meter socket to measure and record voltage, current, power, harmonics, and more, detecting outages, sags, swells, and flicker. We created the lightweight and rugged Guardian™ with your needs in mind. It is perfect for analyzing electrical power issues at the consumer level. After looking through this manual and using the Guardian™ meter socket power analyzer, please contact us if you have any questions about its operation or if you have any ideas for new features or additional products. Total customer satisfaction is our primary goal, and we appreciate any input to help us develop products to meet your future needs. We are always available to discuss how PMI can help you meet your power monitoring needs. Getting Started with the Guardian™ Figure 1 – The Guardian™ power analyzer The Guardian™ meter socket power analyzer, seen above in Figure 1, is an electronic monitoring device which plugs into a standard single-phase 2S meter base. The unit measures and records voltages from line-to-ground on each single-phase line. After data has been recorded, the unit can be connected to a computer using either its proprietary USB cable or wirelessly via Bluetooth®. ProVision™, WinScan™, pmiScan™, or ProVision Mobile™, our data analysis software, can be used to extract the data from the Guardian™. Identification ProVision™, WinScan™, pmiScan™, or ProVision Mobile™ can be used to identify a PMI power analyzer, such as the Guardian™. Identifying the Guardian™ using software ™ can provide you with useful information such as the exact model name, the serial number of your unit, the firmware version, the number of voltage and current channels, and any possible options that your unit may have. This is particularly useful when trying to gather as much information about your Guardian™ as possible when requesting technical assistance. Initialization The Guardian™ power analyzer must be initialized before monitoring data. This is done by either connecting the Guardian™ meter socket power analyzer to your computer using the USB communications cable that came with the power quality analyzer or wirelessly with your computer, PDA, or Field PC using Bluetooth®. See the “PC and Laptop Communications with the Guardian™ power analyzer” section for more information on how to communicate with the Guardian™ meter socket power analyzer using your computer. For more detailed information on initialization, see the software documentation. Installation Please read the safety section carefully before installation. Always exercise extreme caution when installing the Guardian™ meter socket power analyzer. Interrupt the electrical service to the point of connection whenever possible. Always wear gloves and safety glasses, as well as any additional applicable protective equipment. Do not install the Guardian™ unless you are qualified by your utility to install and remove revenue meters. Remove the revenue meter at the installation site using normal safety precautions. Make whatever notations your procedures require about the status and identification of the meter at the time of removal. Attach the green ground clip (found on the rear of the power quality analyzer) to earth ground, or the ground from the service drop. Install the Guardian™ meter socket power analyzer in the meter socket by sliding the blades of the power quality analyzer into the receptacles in the socket. The top of the unit is marked with a sticker inside the front face. If the ground clip is damaged, please call PMI for a replacement cable. The ground clip MUST be connected for proper power analyzer operation. Use the locking ring supplied with the Guardian™ to secure the power quality analyzer to the meter base. Reinstall the revenue meter using the front of the Guardian™ power analyzer as the meter socket. Attach the clamp or locking ring you would normally use to install a meter. The Guardian™ socket should accommodate the existing hardware. Secure your utility’s standard meter seal and make any notations your procedures require about the status and identification of the meter at the time of installation. Battery Ride-Through All Guardian™ meter socket power analyzers come standard with a battery that will allow the unit to continue to record during an outage for approximately 30 minutes. If the battery is fully discharged, it will take approximately 14 hours for the battery to fully charge when the power quality analyzer is connected. Charging is automatically performed by the Guardian™ meter socket power analyzer whenever it is powered. The Guardian™ can detect that it has been unplugged from a meter base and will not continue to record under battery power if it is removed from service (as opposed to an outage whenever it is still connected). No special setup is necessary for the battery option to function. Downloading Data After the Guardian™ has recorded the desired data, it can be downloaded using ProVision™, WinScan™, pmiScan™, or ProVision Mobile™. The Guardian™ may be downloaded in the field using either the USB communications cable or Bluetooth® with a laptop (see PC and Laptop Communications with the Guardian™ power analyzer) or a PMI Field PC (see Field PC Communications with the Guardian™ power analyzer), or you may use Bluetooth® with a PDA (see PDA Communications with the Guardian™ power analyzer). The Guardian™ will stop monitoring whenever it is removed from the meter socket or whenever the power quality analyzer is placed in “Standby” mode using software. Once monitoring has stopped, the data is ready to be downloaded into ProVision™, WinScan™, pmiScan™, or ProVision Mobile™. If using the USB communications cable to download data from the Guardian™ without removing it from the meter base, the Guardian™ will continue monitoring whenever the USB cable is removed from the unit, appending data to the existing monitoring session (assuming the allotted monitoring memory has not been filled). If the Guardian™ is re-initialized, it will start a two-minute countdown, after which it will begin monitoring a new session. ProVision Mobile™ or pmiScan™ can also be used to download data from the Guardian™ using Bluetooth® technology (as well as ProVision™ or WinScan™ if your laptop computer has Bluetooth® communications capability). Data from the Guardian™ meter socket power analyzer may also be downloaded later. Simply remove the unit from the meter base and take it back to the office. Once again, the Guardian™ automatically stops monitoring (even though it has battery ride-through) whenever it is disconnected from the meter base. The recorded data is held in nonvolatile memory so that no data is lost. When the Guardian™ is taken back to your office, connect it to a PC or laptop computer using the included USB communications cable. The green LED illuminates in this mode to indicate that it is in communications mode, and ready for downloading. The recorded data is still in the Guardian™ and can be downloaded again even after it has been re-initialized if you have not yet begun a new monitoring session. The data is not erased until the end of the two-minute countdown of the next monitoring session. For more information on how to download data, please see the software documentation. Analyzing Data See the ProVision™ or WinScan™ documentation to learn about analyzing data recorded by the Guardian™. This documentation is located in the “Manuals” section on the included CD-ROM. Data downloaded with pmiScan™ or ProVision Mobile™ must be imported into either ProVision™ or WinScan™ to analyze. PC and Laptop Communications with the Guardian™ power analyzer Figure 2 – A Laptop Computer Running ProVision™ The Guardian™ meter socket power analyzer can communicate with ProVision™ or WinScan™ running on a desktop PC or a laptop to be identified, initialized, or downloaded. The following operations can be performed using a laptop or desktop PC using ProVision™: Identify power analyzer to display serial number, firmware version, and any options Initialize power analyzer with customized, user-selected settings Set the date and time Retrieve the initialization settings from a Guardian™ power analyzer Download recorded data from power analyzer To connect to the Guardian™ using your desktop PC or laptop, you can use either the supplied USB communications cable or Bluetooth® if your desktop or laptop has Bluetooth® communications capability. If you would like to communicate using USB, use the supplied USB communications cable that was included with your Guardian™ power analyzer to connect the Guardian™ to your computer. Plug the type-A USB plug end of the communications cable into your computer’s USB receptacle. Plug the other end of the cable (a 4-pin female connector) into the port on the bottom of the Guardian™. The unit is powered through the USB connection. The green LED illuminates to indicate that it is in communications mode, and ready for communication. If your laptop or desktop computer has Bluetooth® communications capability, or if you have purchased a Bluetooth® USB adapter, you can communicate with the Guardian™ using Bluetooth® wireless technology. However, the unit must be powered either by the 120VAC meter base or by battery ride-through (only if the power quality analyzer and meter are still connected to the meter base) in order to communicate. See the ProVision™ and WinScan™ software documentation on the supplied CD-ROM for more information on Bluetooth® and USB communications. Figure 3 – WinScan™ and ProVision™ Logos Field PC Communications with the Guardian™ power analyzer Figure 4 – PMI Field PC The Guardian™ meter socket power analyzer can communicate with ProVision Mobile™ running on a PMI Field PC to be identified, initialized, or downloaded. The Field PC has Bluetooth® communications capability, so you can communicate with the Guardian™ using Bluetooth® wireless technology. However, the Guardian™ must be powered either by the 120VAC meter base or by battery ride-through (only if the power quality analyzer and meter are still connected to the meter base) in order to communicate. See the ProVision Mobile™ documentation for more information on communicating with the Guardian™ using the Field PC. PDA Communications with the Guardian™ power analyzer Figure 5 – A PDA Running pmiScan™ In order to connect to the Guardian™ meter socket power analyzer to selected Palm PDAs, the power quality analyzer must have power, either from the meter base (if the power quality analyzer is connected), the battery ride-through (only if the power quality analyzer and meter are still connected to the meter base), or from the USB communications cable. The following operations can be performed using a Palm PDA and PMI’s pmiScan™ and pmiView™ software: Identify the power quality analyzer Initialize the power quality analyzer Download recorded data View real-time data values View real-time voltage, current, and power waveforms View real-time vector diagrams View real time harmonic content Once the Guardian™ is powered, make sure it is in range of the PDA for Bluetooth® wireless communications. To view real-time waveforms, vector diagrams, or harmonics, open up pmiView™. For information on viewing real-time waveforms using pmiView™, see the pmiView™ documentation on the included CD-ROM. If you would like to view real-time data readings from the power quality analyzer, first open up pmiScan™ on your PDA. pmiScan™ has two modes: LDU (which stands for “Local Display Unit”) and Comm (“Communication”). LDU allows the user to scroll through a series of screens showing real-time displays of the measurements that have been enabled, which may include voltage, current, power, phase angle, power factor, displacement power factor, and harmonics. Comm mode, however, allows you to download data or retrieve settings from the Guardian™, along with initializing, identifying, or setting the date and time of the Guardian™. For more information on viewing real-time data and communicating with your Guardian™ using pmiScan™, see the pmiScan™ documentation on the included CD-ROM. What the Guardian™ Records The job of any power monitor is to record all interesting data, and to not record unremarkable data. The difficult part for a monitor is deciding which events are important. This is the primary problem of data reduction. A power analyzer that captured every 60 Hz waveform during a week’s monitoring would never miss an event, but would present the user with millions of useless cycles. Conversely, a power analyzer whose thresholds are set incorrectly may not record anything. Staying between these two extremes involves a balance of thresholds, settings, and record types. The monitor will see an enormous amount of data on its voltage and current inputs – the Guardian™ sees over 1 billion samples per day! Ideally, all this data is reduced to a small report which just shows the important events and measurements. The sifting of data into specific record types accomplishes this task. Triggered Record Types Guardian™ records can be divided into two classes: triggered and non-triggered. Triggered records are event driven. These record types are triggered by a combination of triggering logic and adjustable thresholds, usually voltage-based. If a trigger never happens, nothing is recorded for that record type. As more triggers occur, the Guardian™ collects more data for that record type. The advantage of this class is that nothing is recorded unless something happens. In the ideal case, no problems occur, so nothing is recorded, and no data analysis is necessary. If a trigger does occur, then the Guardian™ logs the event for later analysis. This is a powerful data-reduction tool, and can reduce huge amounts of data into a few small records containing all the significant events. The disadvantage is that success completely depends on good thresholds and settings. A low threshold, such as 0.5%, may cause the Guardian™ to log records that are not really worth analyzing. These extraneous records often hide the few important ones. Conversely, a higher threshold may cause the power quality analyzer to ignore important disturbances. Although it is often possible to use regulatory limits or other known standards to set thresholds, choosing the proper thresholds can be a problem in itself: sometimes you need to know something about the disturbance before you can set proper thresholds to capture it. Despite these potential pitfalls, triggered record types are powerful tools in power line monitoring. They are most useful for capturing voltage disturbances and power quality problems. The captured events are then presented in a text report. Triggered record types include power outage, abnormal voltage, event change (i.e. event capture), significant change, and waveform capture. Non-triggered Record Types The second class of record types is not event driven. These record types are always logging data, regardless of how interesting, important, or unimportant the data may be. The classic example is a paper stripchart, which continuously logs data. There are no thresholds to set, although there may be a parameter to determine how often to collect data. The logged data is usually presented as a graph of data points. Although there may be a large amount of data, using a graph lets the eye pick out important data. Problems such as sags and swells are easy to see in the interval graphs. In addition to voltage quality studies, these record types are used for finding daily trends in current or power values, measuring power factor, etc. The advantage of not having thresholds to set is that there is no question about what data will be recorded. The disadvantage is that sometimes much of the recorded data is unimportant. For non-power quality data such as power factor measurement, there is no disadvantage. These record types include interval graphs, daily profiles, histograms, and energy usage. Using the Guardian™ The Guardian™ can record every available record type simultaneously. Each record type has its own fixed memory allocation, so there is no danger of one errant record type filling the Guardian™ memory to the exclusion of other record types (for example, event capture can never overflow into interval graph memory). Thus the choice usually is not which record types to record, but which record types to examine. In order to answer that question, a good understanding of each record type is required. The details of each record type, and potential uses, are described in the following subsections. Interval graphs The interval graph is one of the most useful record types. In a single interval graph, you can see power quality events such as single-cycle voltage sags and current surges, as well as long-term voltage trends. With the graph, one can examine an entire monitoring session at a glance. What is Recorded The only setting for the interval graph is the interval. This interval, which can be as small as one second to as large as four hours, determines how often the power quality analyzer takes a interval graph data point. Every interval graph the Guardian™ is monitoring uses the same interval settings. During the interval period, the Guardian™ keeps a history of the largest and smallest one-cycle values for each interval graph, as well as a running average. At the end of the interval, the maximum, minimum, and average values for that time period are recorded as an interval graph data point. For example, if the interval is set to one minute (a typical setting), at the end of each minute, the voltage interval graph will record the average root-mean-square (RMS) voltage, the minimum one-cycle RMS voltage, and the maximum one-cycle RMS voltage, all during that minute. All of the 3600 cycles that occur during that minute are used to calculate the average, and for maximum and minimum detection. For more information on these calculations, please see “Calculations” at http://www.powermonitors.com/support/calculations.pdf. These values are presented to the user as three traces on a graph: a maximum, a minimum, and an average. The average trace roughly corresponds to interval graphs as a graph from a paper stripchart power analyzer. The maximum and minimum graphs, however, are unique. Each gives the worst-case value for every interval, with single-cycle measurement resolution. Figure 6 – RMS Voltage and Current Interval Graph Each Guardian™ has at least enough memory to record interval graphs for about a month with a one-minute interval. When the interval graph data fills the allotted memory, the Guardian™ has two options: it can either stop monitoring interval graphs, or go into “wrap-around” mode. In “wrap-around” mode, the oldest interval graph data points are erased to make room for the new ones as they are collected, which allows the Guardian™ to have the latest data at all times. This choice is made by the user during the initialization setup. If the “Interval Graph Overwrite” box is checked in ProVision™ (“Stripchart Overwrite” in WinScan™), the Guardian™ will go into “wrap-around” mode as needed, otherwise it will stop interval graph monitoring when memory is full. For example, if there is memory for four weeks of interval graphs, and the Guardian™ is left in the field for six weeks, then it will have either the first four weeks or the last four weeks of interval graph data, depending on the wrap-around setting. Every Guardian™ can record interval graphs of voltage, current, real power, reactive power, apparent power, power factor, and harmonics magnitudes. Typically, only a few interval graphs are needed at one time. All interval graphs share the same memory, so enabling more interval graphs reduces the total interval graph monitoring time (doubling the number of interval graphs you wish to record will cut your total interval graph monitoring time in half, etc.). When creating an interval graph or report, any “gaps” in the data due to a power outage are filled with zeroes. This happens whenever the Guardian™ loses power on its channel 1 input, and its rechargeable battery runs down. Typical Settings and Suggested Uses There are three settings for the interval graph record types. The primary setting is the interval. This time setting determines how often the interval graph data is recorded. Since the interval graphs always give worst case one-cycle maximum and minimum values, the interval can be set to any time value without a loss of measurement resolution. For example, even if the interval is set to 15 minutes, the maximum and minimum one-cycle RMS values for each 15-minute period are recorded. What is lost by setting the interval to larger values is time information. If there is a voltage minimum of 90V RMS during an interval graph interval, with the interval set to 15 minutes, you are sure that voltage dipped that low for at least a cycle, but you do not know when or how often or how long it happened during that particular 15 minute period. A smaller interval, such as one minute, provides a finer time resolution. The smallest interval allowed for the Guardian™, one second, gives excellent time resolution, but consumes memory 60 times faster than a one-minute setting. Often, the exact time of a voltage dip is not as important as the size – in that case, any reasonable interval setting is fine. The most common setting is one minute. This is a good balance between frequent data collection and long monitoring time. Since most loads that start and stop usually run for longer than a minute, the start and stop effects (such as startup current) are easily spotted in the interval graph. An example is an air conditioner load: a forty-minute period of cycling on and off is obvious in the interval graph as twenty data points at one load current, then twenty data points at low current, all connected by straight lines on the graph. The first interval of the high current period will probably have a much larger current maximum than the rest due to the starting current of the air conditioner. The voltage interval will probably have a dip at the same time. The most frequent reason to use an interval smaller than one minute is for large loads that cycle on and off more frequently than one minute. For example, if an elevator is causing power quality problems, and it only takes 10 or 20 seconds to start at one floor and stop at another, a one-second interval is probably necessary; otherwise, the entire elevator travel will occur during a single interval. In this case, the Guardian™ should not be left to record for days, since it will only hold the last few hours of interval graph data. The best use in this case is to set the interval graph to one second, cycle the load (such as the elevator) for a while in an attempt to reproduce the problem, and then download the data recorded by the Guardian™. In general, the interval should be smaller than the quickest cycling time of a problem load. The most frequent reason to use an interval larger than one minute is to increase the recording time. Setting the interval to two minutes doubles the recording time, without a serious loss of time resolution. Other common settings are five and fifteen minutes, used to match metering or billing increments or regulatory time periods. The second interval graph setting is the “Interval Graph Overwrite” mode or “wrap-around” mode, as we discussed earlier. The best setting for this depends on how the Guardian™ will be used. Some users leave a power analyzer at a problem site until the customer calls with a power quality complaint. The power analyzer is set to a small interval, such as one minute or thirty seconds, and interval graph overwrite is enabled. Because interval graph overwrite is enabled, the interval graphs always have the latest few days of data in memory, by discarding the old data. The data from the Guardian™ is then downloaded, and has the most recent days of interval graph data in memory, no matter how long it was monitoring. This recent data will most likely have the voltage disturbance in it. Other users will disable interval graph overwrite, and leave a power analyzer at a problem site where the power quality problem will definitely occur soon. The Guardian™ will record the first few weeks of interval graph data, and then it will stop interval graph monitoring. The Guardian™ can be downloaded later, knowing that the beginning of the recording session is locked in memory and will not be overwritten. Other users always download the power quality analyzer before it fills up interval graph memory, which make the interval graph overwrite setting irrelevant. The choice depends on the application in which the Guardian™ will be used. The factory default setting is for interval graph overwrite to be enabled. The third interval graph setting allows you to choose which interval graphs are enabled. For all Guardian™ meter socket power analyzers, you can record the following interval graphs: RMS voltage RMS current Real power Apparent power Reactive power Phase angle Power factor Displacement power factor Voltage THD (total harmonic distortion) Current THD (total harmonic distortion) Frequency IFL (Instantaneous flicker level) PST (Perception-short-term flicker) The total monitoring time is shown by ProVision™ and WinScan™ as interval graphs are enabled and disabled during the Guardian™ initialization setup. Another method to increase interval graph memory is to reduce the number of recorded channels. If only one channel is needed on the Guardian™, changing the number of channels from two to one gives twice as much monitoring time. For quantities such as power factor, phase angle, THD, etc., often the average is much more important than the one-cycle maximum and minimum values. The maximum and minimum traces on the graph may be turned off so that they do not obscure the average trace. Daily Profiles Daily profiles are used to spot daily trends in voltage, current, power factor, etc. The entire monitoring session is combined to form the “average” 24-hour day, which is plotted on a graph like an interval graph. Power quality issues are usually not addressed with daily profiles (except perhaps consistently low or high line voltage or harmonic distortion). Rather, average line conditions, such as regulation voltage, load current, etc. are profiled. Figure 7 – RMS Voltage Daily Profile What is Recorded Each measured quantity has only one daily profile per channel in a recording session. For example, there are two voltage daily profiles recorded for a Guardian™ in a recording session, one per channel. The profile is averaged over the entire monitoring session. This average is created by dividing the 24-hour day into 96 time periods, each 15 minutes long. During each 15minute period, the power quality analyzer computes the average value for that profile (voltage, current, etc.). This 15-minute average is then averaged with all the previous days’ averages of that 15-minute period. For example, the first voltage daily profile data point is the average voltage during the 15-minute period from 12:00am to 12:15am, averaged again over the entire monitoring time. If a Guardian™ is monitoring for a week, then this 12:00-12:15am period is averaged seven times over the entire week. There are no settings for daily profiles. All available daily profiles in Guardian™ power analyzers are always enabled, regardless of the settings for any other record types. Memory does not run out for a daily profile; it just keeps averaging as long as the recording session lasts (there is a practical limit of about a year). The Guardian™ records a profile for voltage, current, real power, reactive power, apparent power, power factor, voltage THD, current THD, and phase angle. Suggested Uses Daily profiles are typically used to profile or characterize a parameter, such as average load current or power factor. Since the profile is supposed to reflect average line conditions, the more loads included in the recording, the better the average. Monitoring a single small load such as a small office building will not create a very good profile of distribution line conditions (such as distribution line power factor), since the building would be a small part of the total distribution load. Voltage is somewhat of an exception in that anywhere can be good place to create a profile: every other load (at least those nearby) will see the same distribution line voltage. The ideal location for creating power factor profiles is where a capacitor bank would be placed to correct power factor. The voltage daily profile is normally used to identify voltage regulation problems, or other steady-state low/high voltage issues. The current profile can be used to identify daily trends in load current. This is also possible with the apparent power pro Power factor and reactive power profiles can be used to set capacitor bank timers to correct for power factor only when necessary during the day. The voltage and current THD profiles show when harmonic distortion is present during the day. The more days the Guardian™ records, the better the average created by the profile. A monitoring session that just lasts a single day does not incorporate any daily averaging at all. Since a profile starts with all zeros, a recording session that does not even last 24 hours will include some 15minute blocks with the data still zeroed. A monitoring session that does not even last 15 minutes will have all zeroes for a daily profile. An interval graph can also be used for profiling, but that is not ideal. The interval graph interval is usually set to an interval faster than 15 minutes; a fast interval can show too much information, making it hard to form a good average profile. Often the interval graph only has enough memory for a week or two, limiting the averaging time; the daily profiles have no such limit. Most importantly, the interval graph does not divide the data into an average day period, so it can be difficult to spot daily trends in the graph. Cycle Histograms The cycle histograms contain valuable power quality information as well as information for distribution line profiling. Questions such as “what were the absolute highest and lowest RMS voltage?”, “how many cycles was the voltage below 80V?”, and “what are the most common load currents?” are easily answered. The histograms also contain the raw data necessary to answer more complicated statistical questions such as “What is the probability of a voltage sag below 100V?” and “What high and low limits does the line voltage meet 99.99% of the time?” While the daily profiles give average current, power factor, etc. for distribution profiling, the histograms show what values are the most common– the “mode” in statistical terms. What is Recorded A histogram divides a measurement range into many bins. For example, in the Guardian™, the voltage histogram divides the 150V voltage range into 150 bins, each one-volt wide, giving a bin for 0V, a bin for 1V, 2V, all the way to 150V. After each 60Hz cycle is measured, the voltage is rounded to the nearest volt and placed in the appropriate bin. The bins are really counters that count how many cycles were at that voltage. If the 108V bin has a count of 45, then there have been 45 cycles with an RMS voltage of 108V sometime during the recording session. The histogram does not include time information: those 45 cycles could have occurred anytime during the recording session. There may have been 45 cycles in a row, or three 15-cycle sags, or 45 isolated sags spread out during the entire monitoring session. (To recover the time information, use the interval graph or an event-based report.) Figure 8 – RMS Voltage Cycle Histogram Report Every interval graph maximum and minimum value will have a non-zero count in the corresponding histogram. For example, if the voltage interval graph shows six sags to 108V sometime during the recording session, there should be a count of at least six in the histogram at 108V. The count will probably be somewhat larger, unless each individual sag was only one cycle long. There are no settings for histograms. All available histograms in the Guardian™ are always enabled, regardless of the settings for any other record types. Memory does not run out for a histogram; it just keeps classifying measurements into the bins (by incrementing the bin counters) as long as the recording session lasts. The neutral to ground voltage channel on the Guardian™ records a histogram with tenth-volt increments, from 0.0 to 90.0V. Suggested Uses The power of the histogram is that every cycle is included in the report. Every cycle during the recording session is reflected in the count of one of the bins. If all the counts in a histogram are totaled, then the result is how many cycles, the recording session lasted (minus any time under a power outage). Histograms are presented as a bar graph and a report. The report is in some ways easier to read than the graph. The absolute highest and lowest voltages during the recording session are found by finding the highest and lowest bins with a non-zero count. At that point, you also know how many cycles the voltage was at those extremes, and by glancing at the nearby bins, you know how many cycles the voltage was near those extremes. For example, if all the bins below 110V are zero, then you immediately know that there was not even a single cycle of voltage below 110V anytime during the recording session. If the count at 111V is 1,352,200, then the voltage was at 111V for over 6 hours (1,352,200 = (60 × 60 × 60)). By totaling the counts for all the bins in a voltage range (for example, 0 to 150V), you find how many cycles the voltage was in that range. More complicated power quality questions can be answered by exporting the histogram data to a spreadsheet. By dividing each count by the total of all the counts, the histogram data is normalized, and can represent a sample probability distribution function. If a normal, or bell-shaped probability distribution is fit to this data, a standard deviation is created that can be used to answer “what high and low limits does the line voltage meet 99.99% of the time?”. A cumulative sum over the data will convert the distribution function into a sample cumulative probability function. Correlations between channels can be performed by comparing the probability functions of channels. For the voltage histogram, the user is generally interested in the few cycles that are outside certain limits, not the vast majority of cycles that are perfectly normal. These few cycles usually represent power quality issues. The current, power, and power factor histograms are useful for distribution minute histograms line or load profiling. For these histograms, the few cycles at the extremes are usually unimportant: the vast majority in the middle is the good data. Minute Histograms The minute histogram provides a much “smoother” version of the cycle histogram. Quick sags and swells are averaged out of the data, to show the nominal voltage or current level every minute. Voltage regulation problems are easy to see in the minute histogram. What is Recorded The minute histogram is similar to the cycle histogram. During each minute of the recording session, the voltage is averaged (every cycle is included). At the end of the minute, the histogram bin counter for that average value is incremented. The result is a histogram of one-minute average voltages, instead of one-cycle voltages. For example, if the voltage were 123V for 55 seconds, then 115V for 5 seconds, the average would be 122V, and the 122V bin counter would be incremented. If the interval graph interval is also set to one minute, then the interval graph voltage averages will match the minute histogram counts. Like the cycle histograms, there are no settings for the minute histogram. All available minute histograms in a Guardian™ are always recorded, regardless of the settings for any other record types. Memory does not run out for a minute histogram; it just keeps classifying measurements into the bins (by incrementing the bin counters) as long as the recording session lasts. All Guardian™ meter socket power analyzers will record voltage and current minute histograms. Suggested Uses The voltage minute histogram can reveal voltage regulation problems. Ideally, the line voltage should be at the same value every minute. The larger the spread in the minute histogram, the more the voltage is varying. The center of the spread is (hopefully) the target regulation voltage. This information is also present to an extent in the voltage interval graph, depending on the recording interval and amount of memory. Because the interval graph spreads out the voltage averages as a time graph, it can be more difficult to gauge how long the voltage was at certain levels (although it may be easier to see why the voltage was moving). The minute histogram is also better for this analysis because it does not run out of memory, and is always set for one minute averaging. The current minute histogram shows average load current on a minute basis. The maximum and average load currents are easily spotted on the histogram as the edge and the center of the current spread. Again, this information is usually in the current interval graph, but not as easy to see. The cycle histograms can also be used for voltage regulation problems and load profiling, but the minute histograms can be easier to read since the fast one-cycle events have been averaged out. Energy Usage The energy usage report shows the accumulated real, reactive, and apparent power measured by the Guardian™. The accumulated real power is energy, in kilowatt-hours. The accumulated reactive and apparent powers are kiloVAR-hours and kilovolt-ampere-hours, respectively. These totals are for the entire monitorings session, and are only available on all Guardian™ meter socket power analyzers. What is Recorded Each cycle, the real, reactive, and apparent power values are computed and added to the running totals for the recording session. These values include the effects of voltage and current harmonics. Negative power values are included in the accumulation. For example, if a load is both absorbing and generating power (at different times, of course), the accumulated power will reflect it. A line that varies from leading to lagging power factor may have a small accumulated reactive power reading, even though at different times the actual reactive power flow was large. This would happen if the negative VARs accumulated during the periods of leading power factor mostly cancelled the positive VARs during the periods of lagging power factor. Figure 9 – Energy Usage Report Typical Settings and Suggestedd Uses There are no settings for the enerrgy usage report. This report can be used to meaasure energy consumption of a monitored loadd, or accumulated reactive significant change power in power factor studies. A revenue meter tthat does not total negative power, or does not innclude the effects of harmonics, may show rreadings that differ from this report. Significant Change The significant change record typpe tracks quick fluctuations in the line voltage, wwith single-cycle response, while ignoring graduall changes. Voltage events are time-stamped to thhe second, and listed in a report. If the report is empty, then there were no voltage events that exxceeded the trigger threshold. This is a quickk way to gauge the voltage power quality, becausse only voltage fluctuations exceeding the threshhold are listed. Trigger Logic The significant change record typpe uses a voltage threshold parameter. At the ennd of each second during the recording sessiion, the largest and smallest RMS voltages for thhat second are compared with the “standard” siggnificant change voltage. This standard voltage starts as the nominal voltage picked by the reecorder during the two-minute countdown (typiccally 120V, 208V, 240V, 277V, or 480V). Iff the difference between the standard voltage andd either the maximum or minimum voltage wwas more than the threshold, a significant changee is recorded. In addition, the voltage (either the mmaximum or minimum) that caused the trigger bbecomes the new “standard” until the next significaant change. As an example, consider a “standarrd” voltage of 119V, and a threshold of 2V. Affter 40 seconds, the voltage drops to 118V. No ssignificant change is recorded because the 11V change is smaller than the 2V threshold. After another 35 seconds, the volltage increases to 120V. The change is 2V, fromm 118V to 120V, but no significant change occurs because 120V is only 1V greater than the “standdard” of 119V. After another 23 seconds, the volltage increases to 121V. A significant change iss triggered because the 1V increase created aa 2Vdifference between the 121 maximum voltaages for that second, and the 119V standard. TThe standard voltage is now set to 121V, until thhe next significant change. Only one significant change per ssecond can be recorded per channel. If both thee single-cycle maximum and minimum meet thhe threshold in the same second, the voltage that is furthest from the standard becomes the new staandard. What is Recorded When a significant change is trigggered, the triggering voltage is recorded, along with a date and timestamp (to the second), and thhe channel number. Significant change is recorded seeparately for each voltage channel (although theyy share the same voltage threshold parameter). If significant change memory is filled, significant change monitoring stops. Both voltage chhannels use the same significant change memoryy. Every Guardian™ meter socket recordeer can record over one thousand records. For thee Guardian™, significant change is always enabbled for monitoring. Typical Settings and Suggested Uses The default setting for the significant change threshold is 3V. This setting can be as small as 1V or as large as 8V. Normally, a threshold between 2V and 5V is appropriate, depending on the nominal voltage. A single-cycle disturbance, such as a sag, will trigger significant change if the sag is greater than the threshold. If this happens, the sag voltage becomes the standard, which will trigger another significant change if the voltage returns to its previous level. The significant change report is very useful for determining how often, and to what degree the line voltage is fluctuating. If there are no significant change records, then there were no fluctuations greater than the threshold. A significant change record can be correlated with the interval graph by using its timestamp. Find the same time period in the interval graph to see what the voltage and current were before and after. This may give some indication of the cause of the disturbance. All significant change records during an interval graph interval will be included in a single interval graph data point, consisting of a maximum, minimum, and average value. For example, if the interval is one minute, and six significant changes occur within one minute, they may all fall into the same interval graph data point. (They are still reported individually in the significant change report). The significant change report provides more detail than the interval graph for these disturbances. A key advantage of the significant change report is that only one disturbance per channel can be triggered each second. If multiple disturbances occur during a second, the worst one is recorded. This limits the size of the report, making it much easier to analyze, while still giving single-cycle response. If event change detailed disturbance information on a cycle basis is required, use the event change report. Event change gives much more detail, but is more complicated to examine. The timestamp of a significant change event can be used to find the same disturbance in the event change report for further analysis. For even more detail, waveform capture can be used (if enabled). If the disturbance triggered waveform capture, the raw waveforms of each voltage and current channel can be displayed. Again, the significant change timestamp is used to find the waveform in the list of captured waveforms. Event Change The event change report provides detailed cycle-level information about each voltage disturbance. This is the most detailed report available short of actually looking at raw waveforms with waveform capture. An event is triggered when the voltage moves past any of a series of trip points. Maximum and minimum voltages and currents during the event, the event duration (in cycles), and the current before and after the event are all recorded. Trigger Logic Event change triggering involvess three parameters. The first, the nominal voltagge, sets a baseline voltage level. This is not the samme nominal voltage selected by the abnormal volltage record type during the two-minute countdowwn. The event change nominal voltagge is specified by the user, and is not picked by tthe Guardian™. The second parameter is the thresshold, in volts. The threshold is added and subtraacted to the nominal to form voltage trip points.. These trip points are created all the way dowwn to zero volts and up to the maximum recordeer voltage by using multiples of the threshold vvoltage. For example, a nominal voltage of 1200V and a threshold of 6V would create tripp points at 102V, 108V, 114V, 126V, 132V, 1388V, etc. The voltage region around the noominal voltage, but before any trip points (115VV to 125V in the above example) is called the nomminal band. If the voltage moves from the nominnal band to cross a trip point, an event change is trriggered. This event change continues untiil the voltage either returns back into the nominaal band, or moves past another trip point. Each timme the voltage moves past another trip point, the existing event change ends, and a new event chhange is triggered. The trip points can be visualiized as a grid (every 6V in the above example)) ofrom 0V to 150V (the maximum Guardian™ voltage), and any time the line voltage crosses a grrid line, an event change is triggered. What is Recorded When an event change is triggered, the trigger time is recorded, with one cycle resolution. The RMS current, one cycle before the trigger, is recorded. The direction of the voltage change, or slope, is also recorded. This is displayed in ProVision™ or WinScan™ as a minus for a sag and a plus for a swell. While the event is occurring, the Guardian™ keeps track of the maximum and minimum current and voltage values. When the event ends, the maximum and minimum RMS voltage and currents are recorded, along with the duration (in cycles). One cycle later, the RMS currents are measured to record the currents after the event. All voltage and current measurements are recorded for every channel, regardless of which channel triggered the event. If a sag occurs on three-phases simultaneously, three events will be triggered at the same time. These events are recorded separately, even though they may have the same data in them. Typical Settings and Suggested Uses The nominal voltage should be set as close as possible to the actual nominal line voltage. If a circuit normally runs at about 117V, use 117V as the nominal, not 120V. Event change is not for steady-state line voltage regulation problems (like the abnormal voltage report), but for quick sags and swells. The threshold should be set small enough to catch problem events, but large enough to avoid filling up memory with unimportant data. A good start is 5% of the nominal. The nominal and threshold can be set separately for each channel. To disable event change on a channel, set its threshold to something exceptionally large, like 500V. The minimum event time is not as critical. Ideally, this is set to just larger than the slowest anticipated sag time. For example, if no sags (such as from motor starts, etc.) will take longer than 6 cycles for the voltage to drop to the sag value, the best minimum event time is 7 cycles. This will prevent multiple event changes from the same voltage sag. Otherwise, as the voltage drops lower and lower, past voltage trip points, events will continue to be triggered. Ideally, only one event is triggered for a single sag or swell. A typical value is 10 cycles. This is longer than most sags take to reach the final sag voltage. Event change provides cycle-level detail on sags and swells. A sag which shows up only as a single point on the interval graph can be analyzed in the event change report. Usually, event change is not the first report to analyze in a Guardian™ monitoring, due to its complexity. Check the voltage interval graph for minimum or maximum voltages out of tolerance, or the significant change report for voltage fluctuations. If a disturbance needs further study, use the timestamp to find the fluctuation in the event change report. Here detailed information, such as cycle duration, pre-and post-event RMS currents, etc. is available. The most useful values are the duration and maximum and minimum voltages. This information shows how long the event lasted, and how low or high the voltage went. The cycle timestamp can be useful to determine how far apart several events were if they occurred within the same second. The timestamp is also used to correlate an event change with other reports, such as significant change and waveform capture. The pre and post RMS current cycles can be used to determine whether the load being monitored caused a sag. Consider a sag that triggers an event change. If the current one cycle before the event is low, but the maximum current during the event is high, and the current one cycle after is high (or at least higher than the pre-trigger current), the monitored load probably caused the event. In-rush current from a motor start will cause this type of pattern: the high in-rush current pulls the voltage down, triggering an event. When the in-rush current peak is over, the voltage goes back up, ending the event. The final current is lower than the in-rush current, but higher than the current before the event. Another possibility is a voltage sag where the current during the event is lower than the pre-trigger current (or about the same), and the post-trigger current is about the same. Here, the monitored load probably did not cause the event. Some other load pulled the voltage down, and the monitored load current dropped proportionately with the lowered voltage. When the voltage came back up, then the current rose to its normal level also. ProVision™ and WinScan™ group closely occurring event change records into super-events. A super-event is started when an event starts on any channel. The super-event lasts until there are no running events on all channels for at least an entire second. A complicated voltage disturbance may trigger several closely spaced or back-to-back event changes, but they will be grouped into a single super-event for easier analysis. Event change is recorded separately for each voltage channel. If event change memory is filled, event change monitoring stops. All voltage channels use the same event change memory. The amount of memory used for event change is different for various PMI power analyzers, but the Guardian™ meter socket power analyzer can record over one thousand records. Power Outage The power outage report lists thee date and time of all outages during the recordinng session. An outage is defined by the Guardiann™ to be a voltage sag below 80V, lasting for aat least one-third of a second. Only channel one’ss voltage is used to trigger an outage. The beginnning and end of the outage are time-stamped. In the report, the duration is also given, along withh the total number of outages and the total ooutage time. The Guardian™ has battery ride--through capability, so it will continue to record histograms, interval graphs, etc. during an ouutage. A power outage often triggers waveform capture, which may help reveal the cause of the outage. Flicker The flicker record type is designeed to show voltage variations that cause lights too flicker. The Guardian™ defaults to the threshhold of irritation curve from IEEE Standard 141.. This curve is designed to show only voltage fliicker that is perceived as irritating. When this ooccurs, a flicker event is recorded with the flickerr time and magnitude. Trigger Logic A flicker curve is specified by a llist of allowable voltage thresholds, and a limit oon their quantity in certain time spans. The defaullt parameters conform to IEEE Standard 141 andd can be adjusted in ProVision™. For more informmation on flicker parameters, see the ProVision™™ documentation. Flicker is computed once per seccond, based on the previous second’s one cycle mmaximum, minimum, and one-second averagge RMS voltage levels. The thresholds are giveen as a percentage. If the maximum, miinimum, or average differs from each other by mmore than the percentage for a certain time periiod, then a flicker event counter is incremented. If the counter value exceeds the limit for a certaain time period, a flicker record is triggered. What is Recorded When a flicker record is created, the date and time are recorded, along with the nnumber of voltage events that exceeded the tolerance. The time span over which the flickerr occurred is also recorded. Each channel is reportted separately. Typical Settings and Suggestedd Uses The flicker report is designed to sshow whether utility customers will perceive vooltage variations as flickering lights. The default ccurve is programmed to generate flicker events wwhen a person would become irritated by the levvel of flicker. The IEEE also has a curve that shhows when a person would just perceive flickeering lights, but not become irritated. The validiity of these curves depends on individual circcumstances such as lighting (the curves assume 120V incandescent) and customer senssitivity. The flicker report is used both to confirmm a customer complaint about flickering lightss, and to measure progress in mitigating a probleem. If no flicker events were recorded, then no vooltage variations occurred which exceeded the alllowed limits, and the problem may have been ssolved. Since flickering light perception is so suubjective, merely showing a customer a flicker repport that shows no flicker according to a standardd curve may lessen the complaint by showing that the voltage variations are within standard liimits. If Flicker memory is filled, flickker monitoring stops. The amount of memory useed for flicker is different for various PMI recordeers, but every Guardian™ can record over one thhousand records. Flicker is not meaningful on neuttral-to-ground voltage channels: only channels tthat are used to power lighting generate meaninggful flicker data. Thus, flicker is only recorded forr the line-to-neutral voltage channel on the Guarrdian™. Abnormal Voltage The abnormal voltage record typpe shows if the average line voltage moved past aa low or high threshold from the nominal voltaage. When the trigger occurs, the event is time sstamped to the nearest second. Trigger Logic The triggering logic uses a low aand high threshold, a nominal voltage, and a triggger duration. The thresholds are added and subbtracted to the nominal voltage to find triggeringg points. If the voltage crosses a triggering pointt for longer than the trigger duration, an abnormmal voltage event occurs. The Guardian™ is initialized witth a list of potential nominal voltages (such as 1220V, 240V, etc.), with low and high voltage threshholds for each. The actual nominal is picked by tthe Guardian™ during the two-minute countdown. The average voltage during the countdown is compared to each of the nominal voltages; the closest one becomes the nominal voltage for the entire monitoring session. There are five standard nominal voltages in the software setup (120V, 208V, 240V, 277V, and 480V), and two custom nominal voltages. The custom nominal voltages can be set to any voltage. It is possible to enable and disable the standard and custom nominal voltages. For example, if you wanted to force the Guardian™ to use 230V as the nominal, the standard nominal voltages should be disabled, and both custom nominal voltages set to 230V. If the standard nominal voltages were not disabled, there would be a chance for the Guardian™ to pick 240V during the two-minute countdown, if the line voltage happened to be running closer to 240V than 230V at that time. The nominal voltage is chosen by the Guardian™ separately for each voltage channel. There are separate high and low thresholds for each of the seven nominal voltages. The applicable thresholds are used once a nominal voltage is selected by the Guardian™ after the two-minute countdown. Voltage channels are handled separately; there is a complete set of nominal voltages and thresholds for each. The Guardian™ will automatically select the correct nominal and threshold voltages for each channel. The last abnormal voltage parameter is a trigger duration, in seconds. This specifies how many seconds in a row the voltage must exceed the threshold voltage before the abnormal voltage record is triggered. At the end of each second during the recording session, the Guardian™ compares the one-second average voltage with the nominal and the low and high thresholds. Each threshold actually creates two trip points, one above the nominal and one below. For example, consider a setup where the nominal is 120V, the low threshold is 6V, and the high 12V. The low trip points become 120±6, or 114V and 126V. The high trip points are 120±12, or 108V and 132V. If the one-second average voltage rises above 126V or falls below 114V for longer than the trigger duration, the low abnormal voltage trigger occurs. The use of one-second average voltages eliminates false triggering due to momentary sags and swells. Abnormal voltage is designed to trigger for average-line voltage exceptions, not sub-second events. What is Recorded When abnormal voltage is triggered, the date and time, along with the channel and triggering voltage are recorded. There is a separate listing for each voltage channel, as well as low and high thresholds. Only the first trigger for each threshold is recorded. Typical Settings and Suggested Uses The abnormal voltage report is used to determine whether the voltage drifted outside the thresholds during the recording session. Typically, the abnormal voltage report is used to get a quick read of whether there was any line voltage drift; if so, other record types such as the interval graph and significant change are used for more information. The default threshold settings aree at 5% and 10% of the nominal voltage (for exaample, 6V and 12V for the 120V nominal). Thee high threshold must be larger than the low threeshold. The two custom nominal voltages are presset at 106V and 230V, but should be changed if a different nominal voltage is in use. The default trigger duration is fivve seconds, and can be set as small as one seconnd, or as large as 255 seconds. Loose Neutral The loose neutral report shows wwhether the typical symptoms of a loose neutral hhave occurred. This report is intended for singlee-phase services, such as those measured by the GGuardian™, with voltage channels one and two connnected from line to neutral. The primary symptom of a loosee neutral condition is for one voltage leg to rise inn voltage, and the other to fall, with the sum of the two voltages remaining close to twice the noominal voltage. For example, if the voltages startt at 119V and 121V, then move to 105V and 1355V, a loose neutral is a likely cause: one leg went up, one went down, and the sum is close too twice the nominal (240V). This happens wwhenever the load is not balanced, and the neutraal is disconnected. If this condition iss met for long enough, the loose neutral report iss triggered. Trigger Logic The loose neutral logic uses threee parameters: duration, range, and difference. TThese parameters are used to judge whether one vooltage leg has risen, and one fallen, while the summ remained the same. The difference is a voltage that specifies the minimum difference between the two legs. For example, with a loose neutral where the difference is 16V, there must be at least a 16V separation between the two legs. The range is a voltage that specifies how close the sum of the two voltages must be to twice the nominal voltage. For example, a range of 12V means that the sum of the two legs must be within 12V of twice the nominal voltage. Both the range and the difference conditions must be met for at least the number of seconds specified by the duration. If the duration is set to five seconds, then the difference and range conditions must be met for five consecutive seconds before a loose neutral is declared. One-second average voltages are used. The nominal voltage is the nominal determined during the two-minute countdown by the abnormal voltage record type, and is typically 120V in a single-phase hookup. As an example, assume the difference parameter is 16V, and the range 12V, with 5-second duration. The two line voltages are 119 and 121V. Then one leg moves to 128V, and the other to 110V. The difference between the two legs is 18V, which meets the difference threshold. The sum of the two voltages is 238V, which is within the required 12V (specified by the range value) of twice the nominal (240V). If these voltages persist for 5 seconds in a row, then a loose neutral record will be triggered. If one voltage leg changes due to heavy loading, the range parameter keeps the loose neutral from false triggering. For example, if the voltages start at 119V and 121V, then a heavy load to channel 1 causes it to drop to 105V, with the other leg still at 121V, the difference condition is met (121 × 105 > 12), but the range condition is not met: 105 + 121 = 226, and 226V is not within 12V of the 240V nominal. What is Recorded The date and time of the loose neutral triggering is recorded, along with the voltage on the two channels. Only the first occurrence of a loose neutral is recorded; if the conditions are met again, nothing further happens. The loose neutral report shows whether the neutral may have a bad connection, not the exact times the connection was made and broken. Typical Settings and Suggested Uses The loose neutral report can show the symptoms of an actual loose neutral connection. It is worth investigating if the report is triggered. However, it is possible for the loose neutral logic to be fooled. If both legs are equally loaded, then the two voltages will remain the same even if the neutral is removed. This will prevent the loose neutral trigger from firing. It is also possible for one leg to rise and one to fall due to grossly different loading, and not from an actual loose connection. Thus, it is possible for a loose neutral to trigger falsely, when there is no loose connection. Waveform Capture Waveform capture provides the most detailed report possible: the raw voltage and current waveforms themselves are recorded. With clues provided by the waveform shapes, it is sometimes possible to determine the cause of a voltage disturbance. Events such as capacitors opening and closing, reclosers operating, and lightning strikes can sometimes produce distinctive shapes. The voltage waveforms also reveal the exact duration and magnitude of an event, and how much was coupled across phases. Waveform capture is also useful during steady-state conditions. The current wave shapes can show harmonic currents from non-linear loads, and the voltage wave shapes show the distortion due to harmonic currents and transformer loading. It takes a very large amount of memory to store raw waveforms. The memory size of a single 3-cycle waveform capture record is larger than the size of four hours of interval graph data (at one-minute intervals). Trigger Logic Waveform capture uses a single threshold for triggering. This threshold is a percentage. At the end of each 60Hz cycle, the RMS voltage for that cycle is compared with the RMS voltage of the previous cycle. If the percent change in RMS value is greater than the threshold, waveform capture is triggered. Any voltage channel can trigger waveform capture. The voltage must be at least 5V to trigger. If a trigger occurs, the waveform data is recorded. The trigger test is repeated every cycle, so if the RMS voltage keeps changing, waveform capture will continue to be triggered, until the voltage stabilizes. What is Recorded When a trigger occurs, the waveform data for the triggering cycle is recorded, along with the date and time (to the nearest cycle). The waveform data for the previous cycle is also recorded, to provide a pre-trigger waveform. The user can also customize how many pre and post waveform cycles are recorded. Whenever a waveform is triggered, all voltage and current wave shapes are recorded, regardless of which channel caused the trigger. The waveforms of the next cycle are also recorded, to provide a post trigger waveform. This creates a three-cycle waveform capture record. Many users choose to record two cycles prior to the triggering cycle and six cycles after the triggering cycle, monitoring nine cycles total (including the triggering cycle). This provides a good depiction of what happened just before the triggering cycle and what happened immediately after. If the trigger condition is met again on the next cycle, then an additional cycle of waveforms is added. In general, the waveform capture record continues until waveform capture one cycle after the triggering stops. If the voltage is fluctuating wildly, the entire waveform capture memory could be filled by a very long waveform capture record. If the waveform capture memory is full before the end of the event and the unit is in wraparound mode, the Guardian™ automatically erases cycles of the earliest record to make room for the new data. If the unit is not in wraparound mode, it will not record any waveforms for events occurring after the waveform capture memory has been filled. The waveform data is presented as a graph and a report. The report is usually used only if the data will be exported to a spreadsheet. Typical Settings and Suggested Uses The default setting for triggering a voltage waveform capture is 3%. With this threshold, the RMS voltage has to change by at least 3% in a single cycle. If the threshold is too tight, waveform capture will trigger so often that useless events overwrite the important waveforms. You may also choose to trigger a waveform capture using a voltage value, rather than a percentage. The default trigger setting for the voltage is 5 volts. In order to use this, simply set the percentage setting for waveform capture higher than the voltage setting. For example, if you would like the trigger threshold to be 5 volts rather than 3%, simply set the percentage trigger threshold to a value such as 100%, and the waveform capture will then be triggered by the threshold of 5 volts, as that is the tighter constraint. The default setting for triggering a current waveform is 40%. If you wish to capture more or less current waveforms, simply set this value higher or lower. If you do not wish to capture any waveforms based on variations in current, simply set this percentage to a very high level, so that it is unlikely that a waveform will ever be triggered by a current variation (the highest allowed trigger threshold is 900%). A waveform capture report consisting of just one very long record is an indication that the setting is too small. A report where all the waveform records occurred during the last few minutes of the recording session is another indicator of too small a threshold. In both these cases, the trigger was being met too often. Of course, if no waveform records are present, either the threshold was too large, or the voltage quality was too good. The optimal setting varies from system to system. The exact nature of a voltage disturbance can be seen in the waveform capture report. The peak voltage, length of the sag or swell, and the coupling from phase to phase are easily seen in the graph. Sometimes there are clues regarding the cause of a voltage disturbance. A voltage sag that starts in the middle of a cycle but ends at a zero crossing can be produced by a gas arrestor. The arc continues until the voltage reaches zero, then the arc is extinguished. A recloser operation usually begins and ends at random points in the cycle. A voltage sag that is preceded by an increase in current, but followed by a decrease in current, is usually caused by the monitored load. If the current went down during the sag, and was steady before and after, the sag was probably not caused by the monitored load. Each triggered event is often captured by the significant change and event change reports. The minimum or maximum voltage is usually in the interval graph as well. These reports can be used to place the waveform capture record into the proper overall context. Use the timestamps for each record type to correlate the different reports. A manual trigger captures the voltage and current waveforms during steady state conditions (unless the user happened to press the button at the exact moment of a disturbance). Transformer saturation often shows in a flattened voltage wave shape. If the positive voltage half-cycle is a different shape than the negative half-cycle, even-order voltage harmonics are present. Often the current waveforms will not be sinusoidal. The less they look like a sine wave, the higher the level of current harmonics. Frequently, the neutral current looks much less sinusoidal than the line currents, because some harmonics do not cancel out in a three-phase system, even with a balanced load. The more the current waveform is shifted from the voltage waveform, the worse the power factor. Additional Resources Understanding Guardian™ Records This document, which describes the records that PMI power analyzers can store, is available in PDF format. This and other helpful documents may be found on the ProVision™ installation CD. This document can also be found on the website at http://www.powermonitors.com/support/understanding.pdf. Technical Support Help is always available if one needs additional assistance. The technical support at PMI is widely considered to be the best in the industry. Use one of the following methods to obtain technical support: E-mail Support Send e-mail to: email@example.com. Web Support Submit a support request via the web at http://www.powermonitors.com. Telephone Support Contact us 24 hours a day, 7 days a week for live tech support by calling: (800) 296-4120 Faxes should be sent to: (540) 432-9430 Postal Mail Support All correspondence by post should be addressed to: Power Monitors, Inc. 800 North Main Street Mount Crawford, VA 22841 USA Appendix 1: Warranty Clause Power Monitors Inc. (PMI) warrants each new product manufactured and sold to be free from defects in material, workmanship, and construction, and that when used in accordance with this manual will perform to applicable specifications for a period of one year after shipment. If examination by PMI discloses that the product has been defective, then our obligation is limited to repair or replacement, at our option, of the defective unit or its components. PMI is not responsible for products that have been subject to misuse, alteration, accident, or for repairs not performed by PMI. The foregoing warranty constitutes PMI’s sole liability, and is in lieu of any other warranty of merchantability or fitness. PMI shall not be responsible for any incidental or consequential damages arising from any breach of warranty. Equipment Return If any PMI product requires repair or is defective, call PMI at (800) 296-4120 before shipping the unit to PMI. If the problem cannot be resolved over the phone, PMI will issue a return authorization number. For prompt service, all shipments to PMI must include: The billing and shipping address for return of equipment The name and telephone number of whom to contact for further information A description of the problem or the work required A list of the enclosed items and serial numbers A return authorization number 6. If possible, a copy of the original invoice Equipment returned to PMI must be shipped with freight charges prepaid. After repair, PMI will return equipment F.O.B. factory. If equipment is repaired under warranty obligation, freight charges (excluding airfreight or premium services) will be refunded or credited to the customer’s account. Return equipment to: Power Monitors Inc. 800 North Main Street Mount Crawford, VA 22841 USA Attention: Repair Department Appendix 2: Frequently Asked Questions (FAQs) Firmware: How do I check the firmware version in the Guardian™ using ProVision™? How do I upgrade firmware? How do I use ProVision™ to upgrade the Guardian™ power analyzer’s firmware? 1) To check the firmware version of your Guardian™, first connect to the device using ProVision™. 2) Identify the power quality analyzer by clicking [power analyzer] and then selecting [Identify]. 3) After the identification is complete, click on [View] and the “View Identification Information” window will appear, stating the firmware version of your Guardian™. 4) Go to http://www.powermonitors.com. 5) Go to the technical support page and find the graph on the bottom of the page with current firmware. 6) Look at the latest firmware for the Guardian™ stated on the site, and compare this with the firmware version of your Guardian™ power analyzer. 7) If the latest firmware version listed on the site appears to be newer than the version on your Guardian™ power analyzer, look under “Download Latest Firmware” on the site and select the link for ProVision™. 8) Answer “Yes” to “Do you plan to use ProVision to update firmware?” 9) Click [Next] then [Finish]. 10) This will automatically install the package in ProVision™. 11) Provision™ can detect if firmware is needed and for what device. 12) In ProVision™, select [Options] then [Show Advanced Operations]. 13) Select the Guardian™ in the devices tree, right-click on the device, and select “Upload firmware.” 14) A pop-up box should either say “Files containing new version not found” or “Firmware upgrade necessary.” 15) Follow the prompts if it says “Firmware upgrade necessary.” How do I initialize my Guardian™ power analyzer? 1) Connect to the device using ProVision™. 2) Click on [power analyzer] or right-click on your Guardian™ in the devices tree. 3) Select [Initialize], which should open up the “Basic Screen” window. 4) Set the desired intervals, channels, circuit types, etc. If necessary, select [Advanced]. For more information on using this, see the ProVision™ documentation. 5) Click [Finish]. 6) Answer “Yes” to “Would you like to initialize the power quality analyzer?” 7) When the power quality analyzer has finished initializing, select [Disconnect] and unplug your Guardian™. It is now ready to begin monitoring. How do I check for and how do I upgrade to the most current version of ProVision™? 1) See “Software Installation and Wiring” in the ProVision™ manual. How do I export data files into Microsoft Excel or Word? �Note: You cannot export data into Excel if data exceeds 65,000 lines (try using Word in this case); you may however use the most recent version of Excel (version 2007) to export to it using more than 65,000 lines. 1) Open the data file. 2) Right-click the file and select [Export to Word] or [Export to Excel]. How do I save my favorite Guardian™ initialization settings for later use? 1) In ProVision™, go to the “power analyzer Settings” folder in the devices tree. 2) Right-click on the folder and click [Create Template Settings]. 3) Select [Guardian] from the “power analyzer Type” drop-down menu and click [OK]. 4) Select the desired settings and select [OK]. 5) Click [Finish] when done. 6) Name the settings. (e.g. “Default Guardian Settings) 7) Select [OK]. 8) These new settings should now show up in the “power analyzer Settings” folder. 9) Drag and drop on the power quality analyzer you wish to initialize with the new settings in the device tree. 10) Answer “Yes” to “Would you like to initialize with these settings?” How should I interpret the data recorded by my Guardian™? 1) See “Understanding Scanner Records” on the website at http://www.powermonitors.com/support/understanding.pdf, or on the CD included with your Guardian™. If that does not help, call 1-800-296-4120. How do I import older WinScan™ data files for use with ProVision™? 1) In ProVision™, select [File] then [Import]. 2) Locate and select the folder containing your WinScan™ data files. 3) Answer “Yes” to “Should the folder be added recursively?” 4) The WinScan™ data files should now be displayed in the explorer tree in the under the “Imported Files” folder. How do I change the scaling (upper or lower bounds) on a graph? 1) While looking at a graph, select the [Properties] tab on the right. On the bottom it will say “auto-scale.” Select the plus sign to open the different axis. 2) Change “auto-scale to same bounds” to “True” (the default is “False”). 3) Type the maximum and minimum under each selection. As you change them, the graph reflects these changes. My Guardian™ will not communicate. What should I do? 1) Go to the technical support page on www.powermonitors.com and download the “Communications Troubleshooting” document. Will I need to buy a site license for ProVision™ to install it on multiple computers? 1) No. ProVision™ only works with PMI equipment, so we do not charge the customer in order to make it easier to use our equipment and software. How can I get notified of updated versions of ProVision™ as they are released? 1) You can register to get email updates from PMI or you can check our website every 4-6 months to see what the latest version is. Can I run both ProVision™ and WinScan™ at the same time in my computer? 1) Both programs can be run at the same time for data analysis, however, only one program can be used for communicating with a power analyzer at a time. Also, the speed at which both programs operate may be affected when running them simultaneously. Appendix 3: Troubleshooting Troubleshooting There are several things that could cause communication/download problems with PMI equipment. Listed below are PC and software settings to check and procedures to try: Check all cable connections to see if tight and free of any corrosion or any debris. Check cable status for physical defects, such as cuts or abrasions and missing connector pins. If you are using a laptop PC make sure that any energy-saving features on the Windows operating system are turned off. Sometimes the PC will shut down communications in an attempt to save the battery. If you have a Palm Pilot PDA or any other hand-held PDA that uses a hot sync program, then be sure that the program is turned off. These types of programs – especially the Palm HotSync™ – frequently lock out the serial port, causing communications problems. If you are using a Bluetooth® card or adapter, make sure that you have the latest drivers installed from the manufacturer’s website. Check to insure that the local port setting in WinScan™ or ProVision™ is set for the Bluetooth® adapter port setting on the PC. Make sure that the baud rate setting in the adapter software is set to the correct rate. After checking all of the appropriate items above start fresh on the download process. Disconnect the power quality analyzer and allow it to power down. Close the ProVision™ program. Try the operation again. If you still have communications or download problems after trying all of the above, then there is possibly a hardware problem in the power quality analyzer. Find the “Communications Troubleshooting” document at http://www.powermonitors.com and try some of the suggestions listed. Call Technical Support at 1-800-296-4120. If there appears to be a hardware problem, call PMI at 1-800-296-4120 to arrange for a return authorization to send your unit to the repair department.