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Effective:

March 2000

41-116.1B dated September 1999

Supersedes I.L.

(

) Denotes Change Since Previous Issue

CAUTION

Before putting relays into service, remove all

blocking which may have been inserted for the

purpose of securing the parts during shipment,

make sure that all moving parts operate freely,

inspect the contacts to see that they are clean

and close properly, and operate the relay to

check the settings and electrical connections.

This instruction leaflet applies to the following

types of relays:

TYPE

TIME CHARACTERISTIC

COV-6

Definite Minimum Time

COV-7

Moderately Inverse Time

COV-8

Inverse Time

COV-9

Very Inverse Time

COV-11

Extremely Inverse Time

1.0 APPLICATION

The type COV relay is applicable where it is desired

that an overcurrent unit be set to operate on less than

full load current when the voltage falls below a prede-

termined value, and it is desired not to operate for any

magnitude of current when the voltage is above the

predetermined value. A typical application is overcur-

rent back-up protection for generators.

These relays have been specially designed and

tested to establish their suitability for Class 1E appli-

cations in accordance with the ABB Relay Division

program for Class 1E Qualification Testing, as

detailed in Bulletin STR-1. Materials have been

selected and tested to insure that the relays will per-

All possible contingencies which may arise during installation, operation or maintenance, and all

details and variations of this equipment do not purport to be covered by these instructions. If further

information is desired by purchaser regarding this particular installation, operation or maintenance

of this equipment, the local ABB Power T&D Company Inc. representative should be contacted.

Printed in U.S.A .

ABB Automation Inc.

Substation Automation and Protection Division

Coral Springs, FL 33065

Type COV Voltage Controlled

Overcurrent Relay

Class 1E Applications

form their intended functions for their design life when

operated in a normal environment as defined in

ANSI/IEEE standard C37.90, when exposed to radia-

tion levels up to 10

rads, and when subjected to

seismic events producing a Shock Response Spec-

trum within the limits of the relay rating.

"Class 1E" is the safety classification of the electronic

equipment and systems in nuclear power generating

stations that are essential to emergency shutdown of

the reactor, containment isolation, cooling the reactor,

and heat removal from the containment and reactor,

or otherwise are essential in preventing significant

release of radioactive material to the environment.

2.0 CONSTRUCTION AND OPERATION

The relay consists of: (see Figure 1, page 10).

1. an overcurrent unit (CO)

2. a voltage unit (V) with adjustable resistor

3. an indicating contactor switch unit (ICS)

4. a slow-release telephone type relay, (T)

2.1

OVERCURRENT UNIT (CO)

The electromagnets for the types COV-6, COV-7,

COV-8 and COV-9 relays have a main tapped coil

located on the center leg of an "E" type laminated

structure that produces a flux which divides and

returns through the outer legs. A shading coil causes

the flux through the left leg to lag the main pole flux.

The out-of-phase fluxes thus produced in the air gap

cause a contact closing torque.

The electromagnet for the type COV-11 relay has a

main coil consisting of a tapped primary winding. Two

identical coils on the outer legs of the lamination

structure are connected to the main coil secondary in

a manner so that the combination of all the fluxes pro-

Instruction Leaflet

41-116.1C