T Y P E CA-6 R E LAY
B .
T or q u e C urve s
Connect the relay as shown in the test circuit of
figure 10 . Apply tap value current to the external
transformer. The contacts should open when the fol
lowing restraint current is applied to the relay.
1. Bus Differential Relay
16- 1/ 2
±
5% amperes
2. Transformer Differential Relay
15- 1/2
±
5% ampere
Care should be taken not to overheat the relay
and external transformer during the test.
The restraint current of the transformer dif
ferential relay is less than that of the bus differential
relay in order to compensate for the stronger spring
used on the transformer relay.
C. I n d i c at i ng C o n t a c t o r S w i tc h ( I C S)
Closethe main relay contacts and pass sufficient
d-e current through the trip circuit to close the con•
tacts of the ICS. This value of current should not be
greater than the particular ICS tap setting being used.
The operation indicator target should drop freely.
The contact gap should be approximately .047
inch between the bridging moving contact and the
adjustable stationary contacts. The bridging moving
contact should touch both stationary contacts simul
taneously,
D.
I n d i c at i ng
I n s t a n tan eou s U n i t ( l i T ) - ( W h e r e
S u pp l i ed )
The core screw which is adjustable from the
top of the trip unit determines the pickup value. The
trip unit has a nominal ratio of adjustment of 1 to 4 and
an accuracy within the limits of 10%.
The making of the contacts and target indication
should occur at approximately the same instant.
Position the stationary contact for a minimum of 1/32
inch wipe . The bridging moving contact should touch
both stationary contacts simultaneously.
App ly sufficient current to operate the liT. This
cu!t'ent should be app lied with the external tran sform
er excluded from the circuit.
R o u t i n e M a i n t e n a n c e
All contacts shoul d be periodically cleaned. A
contact burnish er S#18 2A836H0 1 is recommended for
this purpose. The use of abrasive material for clean
ing contacts is not recommend ed, because of the
danger of embedding small particl es in the face of
the soft silver and thus impairing the contact.
C A L l B R A T I O N
Use the following procedure for calibrating the
relay if the relay has been taken apart for repairs or
the adjustments disturbed. This procedure shoul d
not be used until it is apparent that the relay is not
in proper working order . (See "Acceptance Check").
1.
- Adjust the top bearing screw to have
approximately .002 to .006 inch clearance between it
and the shaft.
2.
- Adjust the stationary contact so that
1/4 inch contact se paration is obtained whe n the
moving contact is held in the maximum open position.
3. Minimum
- With operating current applied to
the external transformer, adjust the spring tension
until the relay just operates with following currents
in the 19 tap . :
1 . Bus Differential Relay
0. 145 amp.
2. Transformer Differential Relay
1.0 amp .
4. Torque Check - Connect the relay per the test
circuit of figure 10. Pass tap value current of the
external transformer into the operating circuit of the
relay. The contacts should open when the following
restraint current is applied:
a) Bus Differential Relay
16- 1/2
±
5% amp.
b) Transformer Differential Relay
15- 1/2
±
5% amp.
5. Indicating Contactor Switch (ICS)
Close the main relay co ntacts and pass sufficient
d-e current through the trip circuit to close the con
tacts of the ICS. This value of current should be not
greater than the particul ar ICS tap setting being used.
The operation indicator target should drop freely.
6, Indicating Instantaneous Trip Unit
The core screw must be adjusted to the value of
pickup current desired. It is recommended that the
liT
be set to pickup at 100 amperes. This setting
should be made with the external transformer excluded
from the test circuit.
RENEWAL PARTS
Repair work can be done most satisfactorily at
the factory. However, interchangeable parts can be
furnished to customers who are equipped for doing
repair work. When ordering parts, always give the
complete nameplate data.
1 3
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