Relay Settings; Installation - ABB COV-6 Instruction Leaflet

COV Voltage Controlled Overcurrent Relay
the slow-release telephone relay over a range of 80
to 100 volts. The contacts open to de-energize the
telephone relay if the voltage is higher than the set
value. The drop-out ratio of the unit is 98% or higher.
Relays are shipped from the factory with a 90 volt
setting.
3.3 TRIP CIRCUIT
The main contacts will safely close 30 amperes at
250 volts dc and the seal-in contacts of the indicating
contactor switch will safely carry this current long
enough to trip a circuit breaker.
3.4 TRIP CIRCUIT CONSTANTS
Indicating Contactor Switch Coils.
Ampere Pickup
0.2
1.0
2.0

4.0 RELAY SETTINGS

! CAUTION
In order to avoid opening current transformer cir-
cuits when changing taps under load, start with
RED handles FIRST and open all switchblades.
Chassis operating shorting switches on the case
will short the secondary of the current trans-
former. Taps may then be changed with the relay
either inside or outside the case. Since the tap
block screws carry operating current, be sure
that the screws are turned tight. Then reclose all
switchblades making sure the RED handles are
closed LAST.
4.1 OVERCURRENT UNIT (CO)
The overcurrent unit setting can be defined by tap
setting and time dial position or by tap setting and a
specific time of operation at some current multiple of
the tap setting (e.g. 4 tap setting, 2 time dial position
or 4 tap setting, 0.6 seconds at 6 times tap value cur-
rent). The tap setting is the minimum current required
to make the disc move.
To provide selective circuit breaker operation, a mini-
mum coordinating time of 0.3 seconds plus circuit
breaker time is recommended between the relay
being set and the relays with which coordination is to
Ohms dc Resistance
8.5
0.37
0.10
be effected.
The connector screw on the terminal plate above the
time dial makes connections to various turns on the
operating coil. By placing this screw in the various
terminal plate holes, the relay will respond to multi-
ples of tap value currents in accordance with the var-
ious typical time-current curves.
The factory adjustment of the CO unit contacts
provides a contact follow. Where circuit breaker
reclosing will be initiated immediately after a trip by
the CO contact, the time of the opening of the con-
tacts should be a minimum. This condition is
obtained by loosening the stationary contact mount-
ing screw, removing the contact plate and then
replacing the plate with the bent end resting against
the contact spring.
For double trip relays, the upper stationary contact is
adjusted such that the contact spring rests solidly
against the back stop. The lower stationary contact is
then adjusted such that both stationary contact make
contact simultaneously with their respective moving
contact.
4.2 VOLTAGE UNIT (V)
The voltage unit spring calibration is set to close its
contact when the applied voltage is reduced to 80
volts. The voltage unit can be set to close its contacts
from 80 volts to 100 volts by adjusting the resistor
located at the top left of the voltage unit. The spiral
spring is not disturbed when making any setting other
than the calibrated setting of 80 volts.
4.3 INDICATING CONTACTOR SWITCH (ICS)
There are no settings to make on the indicating con-
tactor switch (ICS).

5.0 INSTALLATION

The relays should be mounted on switchboard pan-
els or their equivalent in a location free from dirt,
moisture, excessive vibration and heat. Mount the
relay vertically by means of the four mounting holes
on the flange for the semi-flush type FT case. The
mounting screws may be utilized for grounding the
relay. External toothed washers are provided for use
in the locations shown on the outline and drilling plan
to facilitate making a good electrical connection
between the relay case, its mounting screws and the
relay panel. Ground wires should be affixed to the
mounting screws as required for poorly grounded or
insulated panels. Other electrical connections may
be made directly to the terminals by means of screws
41-116.1C
3