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8.4 PROTECTION SCHEMES
The following procedure tests the Underfrequency Pickup:
1.
Inject voltage at a frequency above the pickup level into phase V
comes on. Note the pickup value.
2.
Slowly increase the frequency until the Pickup LED goes out. Note the dropout level, which should be the pickup plus
0.03 Hz.
The following procedure tests Blocking From Logic Inputs:
1.
Inject voltage and current above minimum at a frequency to cause a pickup.
2.
Assert a logic input to provide a "Block Underfreq 1 (2)". 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 tests the Underfrequency element Timing:
1.
Connect the "Stop Trigger".
2.
Set the voltage source prefault mode to nominal voltage, current and frequency.
3.
Set the voltage source fault mode to nominal voltage and current, but with a frequency below pickup.
4.
Set the source to prefault mode, reset the timer, and apply to the relay.
5.
Jump the source to fault mode and measure the operating time.
6.
Repeat Steps 4 and 5 four more times and obtain an average of the time intervals.
7.
Reset the relay and disconnect the "Stop Trigger".
b) FREQUENCY DECAY
To test Frequency Decay, 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 checks Minimum Operating Voltage Supervision:
1.
Inject voltage into the V
= I
at a level well above the Minimum Operating Current level. Starting with the V
c
FREQ DECAY PICKUP
cator should remain off.
2.
Inject voltage into the V
= I
at a level well above the Minimum Operating Current level. Starting with the V
c
FREQ DECAY PICKUP
cator should come on while the V
The following procedure checks the Minimum Operating Current Supervision:
1.
Inject voltage into the V
= I
at a level well below the Minimum Operating Current level. Starting with the V
c
Frequency Decay Pickup, drop the frequency of Va at a speed greater than the Frequency Decay Rate setting. The
8
Pickup LED should remain off.
2.
With the V
voltage at a level well above the Minimum Operating Voltage level, increase I
a
Minimum Operating Current level. Currents I
ing with the V
frequency at a level well below the
a
than the
FREQ DECAY RATE
3.
With the V
voltage at a level well above the Minimum Operating Voltage level, increase I
a
Minimum Operating Current level. Currents I
ing with the V
frequency at a level well below the
a
than the
FREQ DECAY RATE
4.
With the V
voltage at a level well above the Minimum Operating Voltage level, increase I
a
Minimum Operating Current level. Currents I
ing with the V
frequency at a level well below the
a
than the
FREQ DECAY RATE
8-30
Courtesy of NationalSwitchgear.com
bus voltage input at a level well below the Minimum Operating Voltage level. Also inject I
a
, drop the frequency of V
at a speed greater than the
a
bus voltage input at a level well above the Minimum Operating Voltage level. Also inject I
a
, drop the frequency of V
at a speed greater than the
a
frequency is dropping.
a
bus voltage input at a level well above the Minimum Operating Voltage level. Also inject I
a
and I
b
setting. The Pickup LED should come on while the V
and I
a
setting. The Pickup LED should come on while the V
and I
a
setting. The Pickup LED should come on while the V
750/760 Feeder Management Relay
. Slowly decrease the frequency until the Pickup LED
a
FREQ DECAY RATE
FREQ DECAY RATE
should be well below the Minimum Operating Current level. Start-
c
, drop the frequency of V
FREQ DECAY PICKUP
a
should be well below the Minimum Operating Current level. Start-
c
, drop the frequency of V
FREQ DECAY PICKUP
a
should be well below the Minimum Operating Current level. Start-
b
, drop the frequency of V
FREQ DECAY PICKUP
a
8 COMMISSIONING TESTS
frequency at a level well below the
a
setting. The pickup indi-
frequency at a level well below the
a
setting. The pickup indi-
frequency at a level well below the
a
to a level well above the
a
at a speed greater
a
frequency is dropping.
to a level well above the
b
at a speed greater
a
frequency is dropping.
to a level well above the
c
at a speed greater
a
frequency is dropping.
GE Multilin
= I
a
b
= I
a
b
= I
a
b
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