GE Multilin 750/760 Feeder Protection System Digital Relay

Feeder Protection System

The 750/760 Feeder Protection System is a digital relay for the management, primary protection and control of distribution feeders.

The relay is easy to use, provides comprehensive protection functions for feeders and backup protection for busbars, transformers and transmission lines, with simple construction and low product life cycle costs.

Key Benefits

- Easy-to-use feeder protection system, supported by an industry-leading suite of software tools

- Accurate built-in metering - eliminates the need for auxiliary metering and reduces costs

- Improved uptime of auxiliary equipment - I/O monitoring

- Reduce troubleshooting time and maintenance costs - IRIG-B time synchronization, event reporting, waveform capture, data logger

- Minimizes replacement time - Drawer construction

- Simplifies testing - Built-in analog capability

- Cost-effective access to information. Supports industry protocols such as DNP and Modbus. Includes an optional 10MB Ethernet port for system integration

- Complete asset monitoring - analog inputs/outputs, full metering (including demand and energy metering)

- Leading-edge technology - flash memory for product field upgrades

- Extended life - optional conformal coating for chemical and humid environments

- Global availability ensures compliance with international norms and standards

Applications

- Primary protection and control of distribution feeders for solidly grounded, high impedance grounded or resonant (Peterson coil) grounded systems

- Busbar blocking/interlocking schemes

- High-speed fault detection for arc-flash mitigation

- Load shedding schemes (bus transfer scheme applications)

- Load shedding schemes based on voltage and frequency elements

- Backup protection for transmission lines, feeders and transformers

- Distributed generation (DG) interconnection protection

Protection and Control

The 750/760 Feeder Protection System is a digital relay for the management, primary protection and control of distribution feeders.

This easy-to-use relay provides comprehensive protection functions for feeders and backup protection for buses, transformers and transmission lines while reducing product life cycle costs.

Time and Instantaneous Overcurrent

The 750/760 has a two-phase TOC element with level detectors for each phase. 750/760 also has two overcurrent elements, most commonly used for primary and backup protection.

Each TOC element has the following programmable features:

- Pickup current levels for tripping, alarming, or control

- Choice of 15 curve shapes (including FlexCurves) and curve multipliers

- Instantaneous or linear reset time characteristics

- Voltage limiting

The 750/760 has two phase IOC elements, each with a level detector.

Each IOC element has a programmable pickup current, a time delay after which the current must exceed the pickup current to operate, and a minimum number of phases required to operate.

Ground Overcurrent Protection

Firmly grounded and low impedance grounded distribution systems require fast ground fault clearance to limit equipment damage. the 750/760 provides ground fault protection with the following features

- Neutral IOC and TOC

- Grounding IOC and TOC

The 750/760 allows the use of directional elements to supervise ground overcurrent protection elements. This means that the 750/760 can be used to provide sensitive tripping for unidirectional faults. Typical applications for directional overcurrent protection include

- Isolating faulty feeders in ring bus or parallel feeder arrangements.

- Protection against faults in the return mains supply from generators in industrial plants

- Sensitive high-speed earth protection for transformers

Sensitive earthing and Restrictive Earth Fault (REF) protection

The sensitive earth and restricted earth fault protection function provides sensitive detection of earth faults.

Sensitive ground fault protection includes

- Instantaneous (50N) and timed (51N) - 2 levels

- Directional monitoring distinguishes between forward and reverse faults.

- Dual polarization (current and voltage) for maximum safety and reliability

750/ 760 for transformer backup protection (grounded converter windings and autotransformers) with RGF function.