Category: GE

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.

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.

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.

Bus Interface Unit Power Supply

The 24 VDC power supply in the Bus Interface Unit provides power for the Bus

Interface Unit itself and logic power for all I/O modules that may potentially be installed

at that station. External power must be supplied for field wiring of input and output

devices. Specifications for the BIU power supply are listed on page 1-11.

The BIU power supply is not damaged by either of the following:

Reversing input voltage on terminals 1 and 2.

Temporary overcurrent conditions on the 6.5 VDC output.

Timing

The Bus Interface Unit provides power to all I/O modules that are installed at the station.

I/O module operation is governed by a System Reset signal to ensure controlled

operation during the power up and shut down processes. As shown in the timing

diagram below, momentary power losses of less than 10 milliseconds do not affect I/O

module operation; however, longer power losses generate a Reset for all system I/O

modules.

Profibus Bus Interface Unit

The Profibus Bus Interface Unit is a small, rugged, intelligent module with a sturdy

aluminum housing. The module has three status LEDs and a connector for a Hand-held

Programmer.

The Bus Interface Unit requires an external source of 24 VDC power.

The BIU’s internal power supply provides power for the operation of the BIU itself, and

logic power for the I/O modules connected to it.

It mounts on a separate terminal block, to which it and all field wiring are attached. The

configuration is stored in non-volatile memory located in the terminal block.

The Bus Interface Unit has a replaceable 1A, 5x20mm 250VAC slow-blow fuse on the

input power lines. The fuse can be changed without disturbing the wiring of any other

modules.

For detailed installation information, please see:

Chapter 2 of this manual. It describes installation and wiring for the Bus Interface

Unit module and terminal block.

Chapter 2 of the Field Control I/O Modules User’s Manual. It summarizes installation

instructions for modules and terminal blocks.  Detailed installation instructions are

also packed with individual Field Control modules.

The individual module datasheets included in the Field Control I/O Modules User’s

Manual, which provide specific module wiring information.

Conformance to Standards (GFK-1179). This manual describes the installation

requirements for programmable control products used in industrial environments,

specifically, in situations where compliance to standards or directives from the

Federal Communications Commission, the Canadian Department of

Communications, or the European Union is necessary. The information in this

manual is applicable for GE Fanuc Series 90-70 and Series 90-30 programmable

controller products, Genius I/O products,  and Field Control Distributed I/O and Control products.

Field Control Environmental Specifications

Vibration

Noise

Temperature

Humidity

Modules perform well where vibration is a factor. Modules are installed

on a panel-mounted DIN rail using the clamp supplied, and with the

panel-mounting feet secured. For information about vibration

standards, please see the Conformance to Standards document (GFK-1179).

Modules are resistant to noise levels found in most industrial applications

when installed according to accepted practices, including proper separation

of wiring by voltage and power level. Modules must be installed on a

conductive (unpainted) DIN rail. The DIN rail is an integral part of the

grounding system.

Modules are tested to the specifications listed in the Conformance to

Standards document (GFK-1179).

Modules operate reliably in ambient air temperatures from 0C (32F)

up to 55C (131F).

Storage temperatures are ±40C (±40F) to +85C (185F).

5% to 95%, non-condensing.

Locations for Field Control

The Profibus Bus Interface Unit and Field Control I/O modules can be located on

equipment, in junction boxes, inside panels, behind operator stations, and in other

locations where space is limited. The area should be clean, free of airborne contaminants,

and provide adequate cooling. Field Control modules can be installed in NEMA

enclosures. The enclosure can be as little as 4 inches (10.16 cm) deep. A 35mm x 7.5mm

DIN rail is required.

The Bus Interface Unit Terminal Block and up to four I/O Terminal Blocks are grouped

together  using the connection cables provided. All of the I/O Terminal Blocks in a group

must be connected either before or after the Bus Interface Unit. A Bus Interface Unit

may not be connected between I/O Terminal Blocks.

The information in this manual is applicable for GE Fanuc Series 90-70 and Series 90-30 programmable

controller products, Genius I/O products,  and Field Control Distributed I/O and Control products.

I/O Modules

Field Control I/O Modules are available in many types to suit a wide range of application

needs. Modules can be installed and removed without disturbing field wiring. One or

two I/O modules may be mounted on an I/O Terminal Block.

I/O Terminal Blocks and Auxiliary I/O Terminal Blocks

An I/O Terminal Block provides mounting, electrical, and field wiring connections.  Each half

of the I/O Terminal Block can be mechanically keyed to accept only an I/O module of a

specific type. Auxiliary I/O Terminal Blocks can be easily attached to an I/O Terminal Block.

They provide the extra connections needed for analog and high-density discrete modules.

For more information, please refer to:

Chapter 2: Installation, which explains wiring to the Bus Interface Unit, and explains

how to install the Bus Interface Unit module on the Field Terminal Block.

Chapter 5: Operation, which explains how the Profibus Bus Interface Unit services I/O.

The Field Control I/O Modules User’s Manual, which describes I/O modules and I/O

Terminal Blocks. This manual also explains module installation and field wiring.

Profibus Bus Interface Unit

The Profibus Bus Interface Unit interfaces Field Control I/O modules to a Profibus I/O bus.

The intelligent processing capabilities of the Profibus Bus Interface Unit allow the

configuration of features such as fault reporting, selectable input and output defaults, analog

scaling and analog range selection for the modules in the station. In addition, the Profibus

Bus Interface Unit performs diagnostic checks on itself and its I/O modules, and relays

diagnostic information to the host (if configured for fault reporting) and to a Hand-held

Programmer.

The Bus Interface Unit mounts on a Bus Interface Unit Terminal Block. The Bus Interface

Unit can be removed and replaced if necessary without removing the wiring or

reconfiguring the I/O station.

Bus Interface Unit Terminal Block

The Bus Interface Unit Terminal Block provides connections for power wiring and single

or dual communications cables. The Bus Interface Unit Terminal Block stores the

configuration parameters selected for the station.