GE C60 Instruction Manual page 573
Breaker protection system
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Also See for C60:
- Instruction manual (682 pages) ,
- Communications manual (532 pages) ,
- Instruction manual (604 pages)
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CHAPTER 7: COMMANDS AND TARGETS
This feature allows pre-scheduling of a PMU measurement at a specific point in time. It can be used to test for accuracy of
the PMU and for manual collection of synchronized measurements through the system, as explained here.
When enabled, the function continuously compares the present time with the pre-set
times match, the function compares the present sequence number of the measured synchrophasors with the pre-set
. When the two numbers match, the function freezes the synchrophasor actual values and the
ONE-SHOT FRACTIONAL SEC
corresponding protocol data items for 30 seconds. This allows manual read-out of the synchrophasor values for the pre-
set time and pre-set sequence number (via the faceplate display, supported communication protocols such as Modbus or
DNP, and the EnerVista UR Setup software).
When freezing the actual values, the function also asserts a
configured to drive an output contact and trigger an external measuring device such as a digital scope with the intent to
verify the accuracy of the PMU under test.
With reference to the following figure, the PMU one-shot function (when enabled) controls three FlexLogic operands:
•
The
PMU ONE-SHOT EXPIRED
at least 30 seconds past the scheduled one-shot time
•
The
PMU ONE-SHOT PENDING
before the scheduled one-shot time
•
The
operand indicates the one-shot operation and remains asserted for 30 seconds afterwards
PMU ONE-SHOT OP
When the function is disabled, all three operands are de-asserted.
The one-shot function applies to all logical PMUs of a given C60 relay.
7.1.5.1 Testing accuracy of the PMU
The one-shot feature is used to test accuracy of the synchrophasor measurement. GPS-synchronized tests sets perform a
similar function to PMUs; instead of measuring the phasor from physical signals with respect to the externally provided
time reference, they produce the physical signals with respect to the externally provided time reference, given the desired
phasor values. Therefore the GPS-synchronized test sets cannot be automatically assumed more accurate than the PMUs
under test. This calls for a method to verify both the measuring device (PMU) and the source of signal (test set).
With reference to the following figure, the one-shot feature can be configured to trigger a high-accuracy scope to capture
both the time reference signal (rising edge of the 1 pps signal of the IRIG-B time reference) and the measured waveform.
The high-accuracy high-sampling rate record of the two signals captured by the scope can be processed using digital
tools to verify the magnitude and phase angle with respect to the time reference signal. As both the time reference and the
C60 BREAKER PROTECTION SYSTEM – INSTRUCTION MANUAL
PMU ONE-SHOT
FRACTIONAL SEC: 0
PMU ONE-SHOT TIME:
2013/06/14 7:58:35
PMU ONE-SHOT OP
operand indicates that the one-shot operation has been executed, and the present time is
operand indicates that the one-shot operation is pending; that is, the present time is
Figure 7-1: PMU one-shot FlexLogic operands
Range: 0 to 99 in steps of 1
Range: YYYY/MM/DD HH:MM:SS
PMU ONE-SHOT TIME
FlexLogic operand. This operand can be
COMMANDS MENU
. When the two
PMU
7
7-5
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