PRS-7910
PRS-7910 49
board, the time and date will be maintained. Therefore when the auxiliary supply is restored the
time and date will be correct and not need to set again.
To test this, remove the auxiliary supply from the relay for approximately 30s. After being
re-energized, the time and date should be correct.
10.4.2.3 Light Emitting Diodes (LEDs)
On power up, the green LED “HEALTHY” should have illuminated and stayed on indicating that the
relay is healthy.
The relay has latched signal relays which remember the state of the trip, auto-reclose when the
relay was last energized from an auxiliary supply. Therefore these indicators may also illuminate
when the auxiliary supply is applied. If any of these LEDs are on then they should be reset before
proceeding with further testing. If the LED successfully reset, the LED goes out. There is no testing
required for that that LED because it is known to be operational.
It is likely that alarms related to voltage transformer supervision will not reset at this stage.
10.4.2.4 Test the HEALTHY and ALARM LEDs
Apply the rated power supply and check that the “HEALTHY” LED is lighting in green. We need to
emphasize that the “HEALTHY” LED is always lighting in operation course except that this device
finds serious errors in it.
Produce one of the abnormal conditions listed in Chapter 4, the “ALARM” LED will light in yellow.
When abnormal condition reset, the “ALARM” LED extinguishes.
10.4.2.5 Test the Other LEDs
Test the other LEDs according to the configuration of the LEDs (through the PRS IED Studio
software). If the conditions which can turn on the selected LED are satisfied, the selected LED will
be on.
10.4.2.6 Test the AC Current Inputs
This test verifies that the accuracy of current measurement is within the acceptable tolerances.
Apply current equal to the current transformer secondary winding rating to each
currenttransformer input of the corresponding rating in turn, see the following table or external
connection diagram for appropriate terminal numbers, checking its magnitude using a
multimeter/test set readout. The corresponding reading can then be checked in the relays menu.
The current measurement accuracy of the relay is ±2.5%. However an additional allowance must
be made for the accuracy of the test equipment being used.
Current channel linearity and precision checkout
Table 10.4.1 Current channel checkout
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