TYPE COQ RELAY
(dead-ended)
under the small filister head
screw located in the Micarta
base of the
contactor switch.
CONTACT CIRCUIT CONSTANTS
Universal Trip Circuit
Resistance of 0.2 ampere Target .... 2.88 ohms
Resistance of 2.0 ampere
Contactor Switch ................. 0.25 ohms
Resistance of Target and
Switch in Parallel ............... 0.23 ohms
INSTALLATION
The relays should be mounted on switch
board panels or their equivalent in a location
free from dirt, moisture,
excessive vibration
and heat. Mount the relay vertically by means
of the two mounting studs for the type FT pro
jection case or by means of the four mounting
holes on the flange for the semi-flush type FT
case.
Either of the studs or the mounting
screws may be utilized for grounding the
relay.
The electrical connections may be made
direct to the terminals by means of screws for
steel panel mounting or to terminal studs fur<>
nished with the relay for ebony-asbestos or
slate panel mounting.
The terminal studs may
be easily removed or inserted by locking two
nuts on the studs and then turning the proper
nut with a wrench.
SETTINGS
There are two settings
namely, the tap
value and the time dial settings.
For the
protection of generators from excessive nega
tive sequence currents,
the settings must be
determined by the type of machine and the full
load current rating of the machine.
Tap Value Setting
This setting is determined by the full load
current of the generator expressed in current
transformer secondary amperes.
6
Time Dial Setting
Settings of the time dial are determined by
the type of machine to be protected.
The time
dial indicates a I
�
T
=
K
curve of a generator
for which the relay protects.
By turning the
time dial, the relay can be used to protect
generators with I
�
T constants varying
from
"30" to "90" as shown in Fig. 3.
ADJUSTMENTS AND MAINTENANCE
All the relays should be
inspected
peri-
odically and the time of operation should be
checked at least once every six months or at
such other time intervals as may be dictated
by experience to be suitable to the particular
application.
Phantom loads should not be used
in testing induction-�ype relays because of
the resulting distorted current wave
form
which produces an error in timing.
All contacts should be cleaned periodically.
A
contact burnisher S#l82A836H01 llirecommended
for this purpose. The use of abrasive material
for cleaning contacts is not recommended, be
cause of the danger of embedding small parti
cles
in
the face of the soft silver and thus
impairing the contact.
The proper adjustments to insure correct
operation of this relay have been made at the
factory and should
not require
after receipt by the customer.
readjustment
If the adjust-
ments have been changed or the relay taken
apart for repairs,
the instructions
should be followed.
below
Adjust the stationary contact by means of
its adjusting screw such that the
contact
spring is just free of the front spring stop.
By means of the time dial,
move the
moving
contacts until they deflect the
stationary
contacts approximately 1/64 inch.
Set the
index pointer such that it points to the "O"
mark on the time dial.
Adjust the stationary
contact by means of its adjusting screw until
the moving and stationary contacts just touch.
This adjustment is to set "O" on the time dial
and provide follow for the contacts.
-
www
. ElectricalPartManuals
. com
