GE 750 Instruction Manual page 32

APPLICATION EXAMPLE
1 - 22
• Power System Data
1. System: 3 , 4 wire
Φ
2. Frequency: 60 Hz
3. Line-to-line voltage: 13.8 kV
4. Maximum current: 600 A
The above data will be used to set the relay system parameters.
• Control System Requirements
1. All protection elements used are to trip the breaker.
2. Breaker position monitoring via 52b contact only.
3. Only current metering is required.
4. Contact Inputs: Remote open and close contacts from RTU.
5. Remote/local selection from panel hand switch. Reset from RTU.
6. Alarm after 100 second delay from substation monitor. This is normally used
to signal the remote center when someone has gained access to the
substation.
7. Contact Outputs:
- Trip and close to breaker control circuit (trip and close relays).
- Relay failure alarm to RTU (self-test warning, no programming req'd).
- Alarm contact to RTU (setup in User Function for "Substation Monitor")
- No data communications to other equipment.
The above data will be used to set the output relays to achieve breaker control and to
set digital inputs for breaker status, remote operations, remote status, and alarm
indication. The example assumes that the communications between the station and
the master control center will be done by the RTU. Alarms, status indication, and
breaker commands will be hard-wired from the relay to the RTU. Please note that,
similar information could be exchanged between the RTU and the relay via an RS485
or RS422 serial link using Modbus RTU protocol. Refer to GE Publication GEK-106473:
750/760 Communications Guide for additional information.
• Instrument Transformer Data
Bus VTs: 2 × Delta connected, ratio = 14.4 kV:120 V
1.
2. Phase CTs: 3 × Wye connected, ratio = 600:5 A
The above data will be used to set the relay system parameters, such as CT and VT
connections, VT secondary voltage, and CT and VT primary to secondary ratios.
• Phase Protection Settings
1. Time Overcurrent 1 (51P1): Curve Shape = Moderately Inverse; Pickup = 840 A;
Multiplier = 20.2
2. Instantaneous Overcurrent 1 (50P1): Pickup = 840 A; Phases Required = Any
Two; Delay = 0 s
3. Instantaneous Overcurrent 2 (50P2): Pickup = 10100 A; Phases Required = Any
Two; Delay = 0 s
CHAPTER 1: GETTING STARTED
750 FEEDER MANAGEMENT RELAY – INSTRUCTION MANUAL