ABB REJ 521 - Testing of the Earth-Fault Measuring Transformer; Testing of the Earth-Fault Stages; Low-Set Stage I; High-Set Stage I

1MRS 752179-MUM
Earth-Fault Relay
Operator’s Manual
REJ 521
29
5.3.1. Testing of the earth-fault measuring transformer
Select the same rated current as in the application.
Before the test is started:
• Record the currently used SGR settings for later restoring.
• Set the relay switchgroups as follows:
The setting values can be those currently in use.
5.3.2. Testing of the earth-fault stages
5.3.2.1. Low-set stage I
0
>
Starting
Close switch S1 and slowly increase the test current until the relay starts and
indicator L3 is lit. Read the start current value from the ammeter.
Operate time
Test according to the selected characteristics.
Definite-time characteristic
Set the test current to 2 x the setting value of stage I
0
>.
Switch off S1, clear the indicators and unlatch the output contacts. The clock is
started by closing switch S1 and stopped by closing output contact PO1.
Inverse-time characteristic
At inverse-time characteristic, the operate time is measured at two different test
current values (2 x I
0
> and 10 x I
0
>). The operate times obtained are compared with
those obtained from the current/time curves of the inverse-time characteristic in
question.
The test procedure is the same as at definite-time characteristic.
5.3.2.2. High-set stage I
0
>>
Starting
Close switch S1 and slowly increase the test current until the relay starts and
indicator L2 is lit. Read the start current value from the ammeter.
Table 5.3.1-1 Switchgroup settings
Setting SGR
I
0
> to SO1 SGR1=4
t
0
> to PO1 SGR2=1
I
0
>> to SO2 SGR3=8
t
0
>> to PO2 SGR4=2