calculator or you may enter a specific value. Once the time has elapsed, the generator output
increments by the Increment value specified in the fault calculator or by the entered value. The
ramping continues until pickup is detected or the Stop value is reached.
Overcurrent pickup ramp technique
When the test is complete, the voltage magnitude and angle, current, and Reach percent error
are calculated for the three phases. One of the inputs is setup to monitor the relay’s contacts.
When the first fault voltage is applied, the timer starts, and the relay stops when the relay trips.
3.5.3 Angle of Torque
The angle of torque test requires two phase ramps. The first ramp is performed by incrementing
the angle CW with the next ramp being incremented CCW. The test will use these two
measurements to calculate the angle of torque.
Measured CW
Torque
Calculated Angle
of Torque
Measured CCW
Torque
Z1
Angle of Torque
3.5.4 Step
The step test is similar to the pulse ramp except the Step test only uses a single pulse. The test
steps from a normal relay setup into the fault condition and waits for the relay to respond. The
test energizes the relay with the pre-fault values, sets the output of the generators to the fault
values, and then starts the timer. The timer input is used to monitor the relay’s trip. The timer
stops once the timer detects the relays contacts have operated. This function is normally used
when timing under/over voltage or frequency relays.
41
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