GE SR760-CASE 750/760Feeder Management Relay® Instruction Manual

DESCRIPTION 

 The 750 and 760 relays contain many features designed to accommodate a wide range of applications. This chapter is pro vided to guide you, the first time user, through a real-world application. The following step-by-step installation example, pro vides you with a quick and convenient way of becoming familiar with the relay. To start, simply power on the unit, and follow the instructions in this tutorial. The example assumes the following system characteristics. It also assumes that relay set points are unaltered from their factory default values.

• Power System Data System: 3Φ, 4 wire Frequency: 60 Hz Line Voltage: 13.8 kV Maximum Current: 600 A

• Control System Requirements All protection elements used are to trip the breaker. Breaker position monitoring via 52b contact only. Only current metering is required. Contact Inputs: Remote open and close contacts from RTU. Remote/local selection from panel hand switch. Reset from RTU. Alarm after 100 second delay from substation monitor Contact Outputs: Trip and close to breaker control circuit (trip and close relays). Relay failure alarm to RTU (self-test warning relay, no programming required). Alarm contact to RTU (setup in User Function for “Substation Monitor”) No data communications to other equipment.

• Instrument Transformer Data Bus VTs: 3 × Wye connected, ratio = 14.4 kV:120 V Phase CTs: 3 × Wye connected, ratio = 600:5 A

• Phase Protection Settings Time Overcurrent 1: Curve Shape = Moderately Inverse; Pickup = 840 A; Multiplier = 20.2 Instantaneous Overcurrent 1: Pickup = 840 A; Phases Required = Any Two; Delay = 0 seconds Instantaneous Overcurrent 2: Pickup = 10100 A; Phases Required = Any Two; Delay = 0 seconds

• Neutral Protection Settings Time Overcurrent 1: curve shape = Moderately Inverse; pickup = 120 A; multiplier = 10 Instantaneous Overcurrent 1: Pickup = 120 A; Delay = 0 seconds Instantaneous Overcurrent 2: Pickup = 2000 A; Delay = 0 seconds You should now be familiar with maneuvering through and editing setpoint messages. As such, we will now limit our discus sion to just the values that must be programmed, in order to meet the requirements of the example application. Any set points not explicitly mentioned should be left at the factory default value。

A) S2 SYSTEM SETPOINTS The S2 setpoints page contains setpoints for entering the characteristics of the equipment on the feeder electrical system. In our example, these characteristics are specified under POWER SYSTEM DATA and INSTRUMENT TRANSFORMER DATA. From this information and the resulting calculations, program S2 setpoints as indicated.

B) For current transformers, make the following change in the S2 SYSTEM SETUP PHASE CT PRIMARY: "600 A" For voltage transformers, make the following changes in the S2 SYSTEM SETUP CURRENT SENSING setpoints page: BUS VT SENSING setpoints page: VT CONNECTION TYPE: "Wye" NOMINAL VT SECONDARY VOLTAGE: "66.4 V" (13.8kV ø-ø ≡ 7.97kV ø-N; 7.97kV / 120 = 66.4 V) VT RATIO: "120:1" (14.4 kV VTpri / 120V VTsec) Make the following change in the S2 SYSTEM SETUP POWER SYSTEM setpoints page to reflect the power system: NOMINAL FREQ: “60 Hz

c) 3 LOGIC INPUTS SETPOINTS The S3 setpoints page is for entering the characteristics of the logic inputs. In our example, these characteristics are spec ified under the Control System Requirements heading. Program S3 setpoints as indicated. For breaker position monitoring, enter the following values in the S3 LOGIC INPUTS INPUT 2 NAME: "Brkr Position (52b)" INPUT 2 ASSERTED LOGIC: "Contact Close" then enter the following value in the S3 LOGIC INPUTS LOGIC INPUTS SETUP setpoints page: BRKR FUNCTIONS setpoint page: 52B CONTACT: "Input 2" For the Remote Open/Close and Reset RTU contacts, enter the following values in the S3 LOGIC INPUTS SETUP setpoints page: INPUT 3 NAME: "Local Mode" INPUT 3 ASSERTED LOGIC: "Contact Close" INPUT 4 NAME: "Remote Open" INPUT 4 ASSERTED LOGIC: "Contact Close" INPUT 5 NAME: "Remote Close" INPUT 5 ASSERTED LOGIC: "Contact Close" INPUT 6 NAME: "Reset" INPUT 6 ASSERTED LOGIC: "Contact Close" then enter the following values in the S3 LOGIC INPUTS LOCAL MODE: "Input 3" RESET: "Input 6" REMOTE OPEN: "Input 4" REMOTE CLOSE: "Input 5" CONTROL FUNCTIONS setpoint page: To setup an Alarm-after-Delay Input. make the following changes to the S3 LOGIC INPUTS 750/760 Feeder Management Relay LOGIC INPUTS USER INPUT A setpoints page

USER INPUT A NAME: "

Substation Monitor" USER INPUT A SOURCE: 

"Input 1" USER INPUT A FUNCTION: 

"Alarm" USER INPUT A RELAYS (3-7): "3----" USER INPUT A DELAY: 

"100.00 s"

d) S5 PROTECTION SETPOINTS The S5 Protection setpoints page contains setpoints for entering protection element characteristics. In our example, these characteristics are specified under PHASE CURRENT and NEUTRAL CURRENT. From this data and the resulting calculations, program the S5 setpoints as indicated.

e) INSTALLATION Now that programming for the sample application is complete, the relay should be put in the Ready state. Note that the relay is defaulted to the Not Ready state before it leaves the factory. This minor self-test warning, diagnostic message, warns that the 750/760 has not been programmed for its intended application. If this warning is ignored, protection is active and will be using factory default setpoints. The Relay In Service LED Indicator will be on.