ABB Automation Inc.
Substation Automation and Protection Division
Coral Springs, FL 33065
Instruction Leaflet
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
.
41-116.1C
Supersedes I.L.
41-116.1B dated September 1999
( ) Denotes Change Since Previous Issue
Effective:
March 2000
Type COV Voltage Controlled
Overcurrent Relay
Class 1E Applications
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-
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
4
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-
