GE 735 Instruction Manual page 38

3.4 SWITCHES
e) CUSTOM SCHEME
In addition to basic protection, the 735/737 can be field configured to perform more complex protection logic using an inter-
nal non volatile setpoint memory. When "custom scheme" switch 8 on the side of the drawout relay is set to off, all custom
scheme features are defeated so that the factory default shown for each option is active. Use the switch 8 off setting unless
any of the special options listed here are required. With switch 8 set on, the internal setpoint memory settings described
here are active. These can be factory preset at customer request or changed in the field using the 735SETUP program run-
ning on a computer connected to the serial port.
If switch 8 is
Communicate > Setpoints > Custom Scheme menu and modifying the settings as required. Interpretation of the
entries from the 735SETUP program screen is as follows:
CUSTOM SCHEME: Factory Default: DISABLED (switch 8 off)
This is a status indication only of the custom scheme enable switch #8 on the side of the drawout relay. It will read: DIS-
3
ABLED if switch 8 is off and ENABLED if switch 8 is on.
TIME OVERCURRENT CURVE SHAPE: Factory Default: ANSI
Selection of ANSI, IAC or IEC/BS142 time overcurrent curve shapes is specified with this setpoint. Consult the appropriate
curve in Chapter 5 to determine trip times for the selected curve. Depending on the setting, phase and ground curve shape
dials will be defined as:
ANSI
Moderately Inverse
Normal Inverse
Very Inverse
Extremely Inverse
Definite Time
BLOCK INSTANTANEOUS ON AUTORECLOSE: Factory Default: Disabled
When the 735/737 is used in conjunction with an autoreclose scheme, it may be desirable to block instantaneous trips after
an autoreclosure operation. This prevents nuisance trips due to the normally high inrush currents typically experienced in
these situations and allows a coordinated clearance of permanent faults by fuses or inverse-time overcurrent relays. A pro-
grammable phase and ground instantaneous trip block time from 0 to 180 seconds can be programmed with this setpoint. If
this setpoint is enabled, when the 735/737 first detects current in any phase, it disables phase and ground instantaneous
trips for the duration of this time setting. Time overcurrent protection however is enabled during this time.
AUX TRIP RELAY: Factory Default: MAIN TRIP (AUX relay follows TRIP relay)
The Auxiliary relay can be set to MAIN TRIP, 86 LOCKOUT, or GROUND TRIP.
• If MAIN TRIP is enabled the AUX relay follows the TRIP relay.
• If 86 LOCKOUT is enabled the AUX relay with output contacts connected to terminals G6 and H6 is programmed to act
as an 86 Lockout relay. When untripped, the contacts are normally closed enabling the breaker close coil circuit. (If
control power to the relay is not present, this contact opens effectively creating a lockout condition.) When a trip
occurs, the trip contacts (G5/H5) will momentarily pulse to trip the breaker while the 86 Lockout contacts (G6/H6) will
latch open preventing the close coil contacts from being activated. To restore the 86 Lockout contacts to the normally
closed condition, either the front panel CLEAR key must be pressed to clear the trip condition and indicators, or a "Trip
Reset" command must be received via the communications serial port. If the 86 Lockout relay is not reset and control
power is lost, the 86 Lockout contacts will remain in the lockout condition after power is restored.
• If GROUND TRIP is enabled the AUX relay will respond only to TIMED or INSTANTANEOUS Ground Faults. Phase O/
C Trips will only trip the TRIP relay. Ground Fault Trips will only trip the AUX relay.
3-10
set on, use the
735SETUP
IAC
Short Time
Inverse
Very Inverse
Extremely Inverse
Definite Time
735/737 Feeder Protection Relay
program to view
IEC/BS142
Short Time
IEC A
IEC B
IEC C
Definite Time
3 SETUP AND OPERATION
settings by selecting
GE Power Management
the