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Abstract
What follows is a general overview of some of the basic event driven recorder functions available when using ProVision Software and some instructions on getting started with collecting useful data based on pre-established event triggers.
Introduction
One of the two classes of recording for the PMI recorders is the event driven type. The main advantage of an event driven recording is that it limits the data collection to information within pre-established parameters. This can result in longer recording times for a given amount of memory. If the trigger parameters are set correctly, this can greatly reduce the amount of data collected thus reducing the time needed to analyze the data.
The operator sets the trigger by means of trigger logic and threshold. The threshold is usually set to an exact voltage to activate the trigger. The main disadvantage is that the correct trigger levels need to be set in advance to collect the data. If the trigger level is set too high the recorder will not trigger. If it is set too low it will trigger on everything. Choosing the correct trigger point to get the data that is needed can be tricky and might require some trial and error, especially if the disturbance is very small. Unless it is evident in advance what disturbance should be identified, it is usually more prudent to start with the default settings and proceed.
Using the default setting as a reference point is a very good place to start. This way the operator can customize using the proper trigger logic and thresholds available to hone in on the best setup for a particular location. To find out what the default settings are when a recorder is available to hook up, just connect it to a computer via USB and start up Provision. After Provision has started, select View > Devices > Local and then locate the unit’s name and Serial Number. Go to Initialize > Advance hit Next to advance to Waveform Capture 2/7. As shown in Figure 1.
Figure 1. Default waveform capture settings
If a recorder is not available for hook up, it is possible to find out what the default settings are for a specific recorder by navigating to Recorder Settings via the Devices window. In the Recorder Settings window, right click and select Create Template Settings, select the recorder type with mouse thumb wheel and then click OK. Then click Advanced > Restore Default and then go to Next which will display the Waveform Capture (2/7) window as it appears in Figure 2.
Figure 2. Viewing default settings without connecting a recorder
Waveform Capture
The Waveform Capture (2/7) window allows the voltage trigger thresholds to be changed, either as a percentage of voltage per cycle or raw voltage change per cycle.
CAUTION: The device will always trigger on the lowest absolute voltage setting, whether it is specified in percentage or voltage!
If voltage is the desired trigger, it may be necessary to raise the voltage percentage to make sure the recorder triggers on voltage level only and vice versa. There are many other ways for the recorders to event trigger, such as waveform capture, event capture, flicker, abnormal voltage, transient capture, significant change, power outage, and loose neutral.
Event Capture
Event Capture parameters are shown in Figure 3.
Figure 3. Settings for event capture
The first column needs to be setup for the nominal voltages which can be configured from 1 to 600 volts for each of the voltage input channels. The second column is the voltage trigger threshold which can be set from 1 to 255 volts. The third column, the minimum event time, deals with the minimum number of cycles outside of the threshold before the recorder will be triggered. This parameter can be set from 1 to 255 cycles.
As noted above the Loose Neutral parameter variables are duration, range and difference. The Loose Neutral is triggered when one voltage leg has risen, and the other one falls but the sum of the voltages stays the same. The number in the differences column is the minimum voltage required between the two legs to trigger the recorder. The range parameter is a voltage parameter that deals with how close the sum of the two voltages must be to twice the nominal voltage. The Trigger Duration is the minimum amount of time specified in seconds that both the Range and Difference conditions must be met before the recorder to trigger. A one second RMS average of the voltage is required before trigger is initialized.
Flicker
Standard default flicker parameters are shown in Figure 4.
Figure 4. Standard default flicker parameters
The Flicker function is used to show variations in voltage that can cause lights to flicker.
The default values are derived from the IEEE Standard 141 threshold of irritation. The defaults are setup to only show voltage flicker conditions that are perceived as irritating. If the Flicker thresholds are met, the flicker event is recorded with the time and magnitude data. The graph is shown in Figure 5.
Figure 5. IEEE Standard 141 Threshold of irritation
Abnormal Voltage
The Abnormal Voltage trigger occures if the average line voltage passes a low or a high threshold from the norminal voltage. The trigger logic uses a high and low threshold, a nominal voltage, and a time duration. The thresholds are subtracted and added to the nominal voltage to find the triggering points. When the voltage passes a trigger point for longer than the trigger duration value, an Abnormal Voltage event will occur. If the trigger occurs, the event is timestamped to the nearest second. Abnormal voltage default values are found in Figure 6.
Figure 6. Abnormal voltage default values
The Abnormal Voltage function is designed to measure and pick the correct standard Nominal range from the Abnormal Voltage setup screen above. This is done during the two minute countdown when the Recorder is first powered up. The default choices are 120, 208, 240, 277, 480 and two custom ranges. The custom ranges can be set to any value from 0 to 600 volts. The custom and standard ranges can be enabled and disabled depending on what the operator’s needs are. As seen in the screen above, there are separate high and low threshold settings for each of the seven nominal voltages. Each of the voltage channels are handled separately and there is a complete set of nominal values and thresholds for each channel.
The finally Abnormal Voltage parameter is the Trigger Duration. The Trigger Duration setting specifies the length in seconds that the voltage must exceed the threshold before the Abnormal Voltage function is triggered.
Transient Capture
Figure 7 shows the Transient Capture setup screen with the current defaults.
Figure 7. Transient capture screen showing defaults
The Transient Capture function is only available on the Revolution and Vision product. Unlike the Waveform Capture (2/7) which requires a complete cycle to get an RMS value to trigger, the Transient Capture function is peak detect and samples at a rate of 16,666 samples per cycle or 1 MHz sample frequency, (1x10 6 Hz/ 60Hz = 16,666 samples per cycle), allowing it to respond and trigger on much faster events. This is very useful for recording events such as switching spikes and lightning.
Conclusion
This paper is a general overview of some of the basic Event Driven recorder functions using ProVision Software. It can be used as an instruction guide for getting started in collecting useful information for an inexperienced operator.
Detailed instructions are included to navigate the operator through the default settings in a step-by-step fashion including screen captures. Unless the operator knows upfront exactly what disturbance needs to be identified, default settings are a good way to get preliminary information on a system allowing the operator to decide what parameters need to be changed to enhance that data collection process.
Cowles Andrus, III
Communications Specialist
candrus@powermonitors.com
http://www.powermonitors.com
(800) 296-4120
