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8.4 PROTECTION SCHEMES
To test the Reverse Power element, use the test connections specified in Figure 8–1: Relay Test Wiring – Wye Connection
or Figure 8–2: Relay Test Wiring – Delta Connection on page 8–3. The Indications and Operations are as outlined for
Phase TOC 1 on page 8–16.
The following procedure tests Pickup for the Reverse Power element:
1.
Apply a three phase nominal voltage to the relay.
2.
Adjust the phase angle between the voltage and current to be 180°.
3.
Inject current into all three phases and increase slowly until Reverse Power operates; note the pickup value.
4.
Calculate the power value from the following formula:
I is the pickup value expressed as a primary value, and cos(θ) is cos 180° (in this case, 1.0).
5.
Express the measured power as a percentage of the rated power calculated using rated values in the above equation.
The value should be within specifications for this element.
6.
Adjust the phase angle to 100°, 120°, 240°, and 260°, checking the current pickup value for each angle. Calculate the
relay pickup power for each angle using the formula given in Step 4.
The following procedure tests the Blocking From Logic Inputs for Reverse Power:
1.
Cause the reverse power element to pickup.
2.
Assert a logic input to provide a "Block Reverse Power". The Pickup LED should immediately go out.
3.
Repeat Steps 1 and 2 for logic input "Block 1 Trip Relay" as required.
The following procedure checks Timing for the Reverse Power Element:
1.
Connect the Stop Trigger.
2.
Preset the input voltage and current to provide a reverse real power which is 150% of pickup.
3.
Inject the preset voltage and current and note the measured delay time. Reset the timer.
4.
Repeat Step 3 four more times and obtain an average of the time intervals.
5.
Disconnect the Stop Trigger.
8
8-32
Courtesy of NationalSwitchgear.com
×
P
3
VI
cos
=
750/760 Feeder Management Relay
8 COMMISSIONING TESTS
8.4.9 REVERSE POWER
θ ( )
, where V is the primary line to line voltage,
GE Multilin
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