Westinghouse KC-4, Installation, Operation & Maintenance Instructions Manual

Page: 99 / 178

I.L. 41 -778.1 K
T Y P E
All contacts should be periodically cleaned. A
contact burnisher S#l 82A836H0 l is recom­
mended for this purpose. The use of abrasive
material for cleaning contacts is not recommend­
ed, because of the danger of embedding small
particles in the face of the soft silver and thus
impairing the contact.
CALI B RATI O N
U se the following procedure for calibrating
the relay if the relay has been taken apart for re­
pairs or the adjustments have been disturbed. This
procedure should not be used unless it is apparent
that the relay is not in proper working order.
(See "Acceptance Check").
Phase
&
Ground Overcurrent Unit
The moving contact assembly has been factory
adjusted for low contact bounce performance and
should not be changed.
The set screw in the stationary contact has
been shop adjusted for optimum follow and this
adjustment should not be disturbed.
l . The upper pin bearing should be screwed
down until there is approximately
l
/64" clearance
between it and the top of shaft bearing. The upper
pin bearing should then be securely locked in posi­
tion with the lock nut. The lower bearing position
is fixed and cannot be adjusted.
2. The contact gap adjustment for the over­
current unit is made with the moving contact in
the reset position, (aganist the right side of the
bridge.) Advance the stationary contact until the
contacts just close. Then back off the stationary
contact 2/3 of one turn for a gap of approximately
.020" . The clamp holding the stationary contact
housing need not be loosened for the adjustment
since the clamp utilizes a spring-type action in
holding the stationary contact is position.
3. The sensitivity adjustment is made by vary-
ing the tension of the spiral spring attached to the
moving element assembly. The spring is adjusted
by placing a screwdriver of similar tool into one of
the notches located on the periphery of the spring
adjuster and rotating it. The spring adjuster is
located on the underside of the bridge and is held
in place by a spring type clamp that does not have
to be loosened prior to making the necessary ad­
justments.
Insert the tap screw in the minimum value tap
setting and adjust the spring such that the contacts
will close when energized with the required cur­
rent. The pick up of the overcurrent unit with the
tap screw in any other tap should be within ± 5%
of tap value.
If adjustment of pick-up current in between tap
settings is desired, insert the tap screw in the next
lowest tap setting and adjust the spring as des­
cribed. It should be noted that this adjustment
results in a slightly different time characteristic
curve and burden.
Indicating Contactor Switch (ICS)
Close the main relay contacts and pass suffi­
cient de current through the trip circuit to close
the contacts of the ICS. This value of current
should be not greater than the particular ICS tap
setting being used. The operation indicator target
should drop freely.
The contact gap should be approximately
.04 7"
between the bridging moving contact and
the adjustable stationary contacts. The bridging
moving contact should touch both stationary con­
tacts simultaneously.
RENEWAL PARTS
Repair work can be done most satisfactorily
at the factory. H owever, interchangeable parts can
be furnished to the customers who are equipped
for doing repair work. When ordering parts,
always give the complete nameplate data.
1 3
www
. ElectricalPartManuals
. com