GE 750 Instruction Manual page 273

Protection Schemes
GE Multilin
5. Turn current off.
The following procedure checks indications and operations caused by a Control
function:
1. Inject current to cause a pickup and wait until the element times-out. Check
that any output relays programmed to operate (as well as their associated LED
indicators) operate.
2. Slowly reduce the current until the Pickup LED goes out. Check that any output
relays programmed to operate (as well as their associated LED indicators) reset.
3. Turn current off.
The following procedure checks indications and operations caused by a Latched
Alarm function, with RESET key resetting:
1. Inject current to cause a pickup and wait until the element times to Alarm.
2. Check that the Alarm and Message LEDs are flashing, the Active Alarm message
is displayed, and any output relays programmed to operate (as well as their
associated LEDs) operate.
3. Slowly reduce the current until the Pickup LED goes out. Check that the Alarm
and Message LEDs are flashing, and that any output relays programmed to
operate (as well as their associated LEDs) reset.
4. Press the front panel RESET key. Check that the Alarm and Message LEDs go off,
and the Active Alarm message is no longer displayed.
5. Turn current off.
The following procedure checks blocking From Logic Inputs. Note that this
procedure is different for Phase TOC2; see the next section for details.
1. Inject current to cause a pickup.
2. Assert a logic input to provide a "Block Phase Time 1". The Pickup LED should
immediately go out.
3. Repeat Steps 1 and 2 for logic inputs "Block Phase O/C", "Block All O/C" and
"Block 1 Trip Relay" as required.
The following procedure checks timing:
1. Connect the Stop Trigger.
2. Preset the injection current level to 2.0
the timer.
3. Inject the preset current into Phase A and note the measured delay time. Check
this time against the time established by the settings and reset the timer.
4. Preset the injection current level to 4.0
the timer.
5. Inject the preset current into Phase B and note the measured delay time. Check
this time against the time established by the settings and reset the timer.
6. Preset the injection current level to 7.0
the timer.
7. Inject the preset current into Phase C and note the measured delay time. Check
this time against the time established by the settings.
8. Turn current off and disconnect the Stop Trigger.
The following procedure checks Linear Reset Timing:
1. To confirm that the TOC element is using linear reset timing, if so programmed,
inject a current above the pickup level for approximately half the time required
to Trip.
2. Turn the current off, reset the interval timer, and then re-apply immediately.
3. The time-to-trip should be much less than the trip-time established by the
settings.
The following procedure checks the voltage restrained Phase TOC function:
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Feeder Management Relay
pickup. Turn the current off, and reset
×
pickup. Turn the current off, and reset
×
pickup. Turn the current off, and reset
×
750/760
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