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

Page: 155 / 178

on the timer module front plate and terminal 8 of
the relay (common negative).
The control timer should be set for at least 1 6
milliseconds longer than the B F timer. This allows
for pickup time of the reed relay ( 1 to 3 ms), A R
relay pickup (3 to 5 ms) and operate time of the
ojc unit (3 to 8 ms) .
The range o f adjustment i s a minimum o f 1 00
0 ms ( ! 50 to 250 ms ) . The control timer is shipped
from the factory set for 200 ms.
0
A 1 50 to 600 ms timer is available and is ship­
ped with the timer set for 600 ms.
The control timer acts essentially as a pulse
stretcher on the BFI input and then resets. Since
the overcurrent unit never picks up on successful
clearing, it cannot be used as a cutoff for the
breaker failure timer.
BF T I M E R
A calibrated scale located o n the front of the
timer module permits setting the time delay from
18 to 1 75 milliseconds. The scale is calibrated in 25
ms increments. I f more accurate settings are
desired an oscilloscope or electronic timer may be
connected between the upper red test jack on the
timer module and terminal 8 of the relay (Com­
mon N egative) . Jumpering test point TP6 and TP7
on the timer module prevents the control timer
from resetting the BF timer and will help in set­
ting the BF timer. Remember that if the control
timer is set shorter than the BF timer, the BF timer
will not be able to operate the reed relay ( R R).
0
A 50 to 500 ms B F timer with 50 ms scale
increments is also available.
A locking tab is provided to hold the BF timer
setting from being accidentally changed .
0 The timer is shipped set at 1 75 ms. The 50 to
500 ms timer is shipped set at 500 ms.
The breaker failure timer should be set to ex­
ceed the breaker normal clearing time by an ap­
propriate margin. Where the breaker contains a
I. L.
41 -776.5A
resistor that is inserted on tripping and the over­
current fault detectors are set below the resistor
current, the additional time for this interruption
must be included. A secure margin for the SBF- 1
is 2 cycles. (33 ms)
I N DI CATI NG CO NTACTOR
SWITCH ( I CS)
Connect the lead located in front of the tap
block to the desired setting by means of the con­
necting screw.
When the relay energizes a 1 25 or 250 Vdc type
WL relay switch or equivalent use the 0.2 amp tap.
For 48 Vdc applications set the unit in the 2 amp
t a p a n d u s e a t y p e W L r e l a y w i t h a
S#304C209GO 1 coil or equivalent.
I N STALLATION
The relays should be mounted on switchboard
panels or their equivalent in a location free from
dirt, moisture, excessive vibration and heat.
Mount the relay vertically by means of the rear
mounting stud or studs for the type FT projection
case or by means of the four mounting holes on the
flange for the semi-flush type FT case. Either the
stud or the mounting screws may be utilized for
grounding the relay. External toothed washers are
provided for use in the locations shown on the out­
line and drilling plan to facilitate making a good
electrical connection between the relay case, its
mounting screws or studs, and the relay panel.
Ground wires are affixed to the mounting screws
or <;tuds as required for poorly grounded or in­
sulating panels. Other electrical connections may
be made directly to the terminals by means o f
screws for steel panel mounting o r t o the terminal
stud furnished with the relay for thick panel moun­
ting. The terminal stud may be easily removed or
inserted by locking two nuts on the stud and then
turning the proper nut with a wrench.
For detail information on the FT case refer to
I . L. 4 1 -076.
ADJUSTM ENTS AND
MAINTENANCE
The proper adjustment to insure correct
operation of this relay have been made at the fac­
tory and should not be disturbed.
5
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