Reverse Power; Monitoring - GE 750 Instruction Manual

750/760
Feeder Management Relay

Reverse Power

Current Monitoring
7–36
cannot be performed by the breaker. The element should not generate an
output.
To test the Reverse Power element, use the test connections specified in FIGURE 7–
1: Relay Test Wiring – Wye Connection or FIGURE 7–2: Relay Test Wiring – Delta
Connection on page 7–4. The Indications and Operations are as outlined for Phase
TOC 1 on page 7–18.
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:
where V is the primary line to line voltage, I is the pickup value expressed as a
primary value, and cos(
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.

Monitoring

a) Phase Current Level
To test Phase Current monitoring, use the test connections specified in FIGURE 7–1:
Relay Test Wiring – Wye Connection or FIGURE 7–2: Relay Test Wiring – Delta
Connection on page 7–4. The Indications and Operations are as outlined for Phase
TOC 1 on page 7–18, except that this element has no Trip function.
1. Set the Delay time to 0.
2. Inject current at a level below the pickup level into Phase A.
3. Slowly increase the current until pickup is reached and the element generates
an output.
4. Slowly reduce the current until the element resets, which should be 2% of CT
less than pickup when pickup
5. Repeat Steps 2 to 4 for phase B and C current.
http://www.GEmultilin.com
) is cos 180° (in this case, 1.0).
θ
CT or 97 to 98% of pickup when pickup > CT.
≤
Monitoring
P 3 VI × cos θ ( )
,
=
GE Multilin