Manual MRI3 GB
Woodward
DOK-TD-MRI3 Rev.A
51
6.4.8 Test circuit earth fault directional feature
Figure 6.3: Test circuit
For testing relays with earth fault directional feature, current and voltage input signals with adjusta-
ble phase shifting are required. Figure 6.3 shows an example of a single phase test circuit with ad-
justable voltage and current energizing the MRI3 relay under test.
For testing a relay with earth fault directional feature, one of the input energizing quantity (voltage)
shall be applied to the relay with a constant value within its effective range. The other input energiz-
ing quantity (current) and phase angle shall be appropriately varied.
With the aid of phase angle indicated on the display the correct function of the relay can be
checked (ER-relay type).
Parameters I
E>
and I
E>>
should be set to EXIT.
The following measured values are shown:
Measured value
LED
Earth current
E, I
E>
Active share
E, I
P
Reactive share
E, I
Q
Earth voltage
E, U
E>
Angle E,
I
E>
, U
E>
Table 6.4