Westinghouse
I.L. 41-776.5
INSTALLATION
•
OPERATION
•
MAINTENANCE
INSTRUCTli®NS
TYPE SBF-1 CIRCUIT BREAKER
FAILURE RELAY
CAUTION:
It is recommended that the user of
this equipment become acquainted with the infor
mation in these instructions before energizing the
relay. Failure to do so may result in damage to the
equipment. Before putting the relay into service,
operate the relay to check the electrical connec
tions.
Printed circuit modules should not be removed or
inserted while the relay is energized. Failure to
observe this precaution may result in an undesired
tripping output or cause component damage.
APPLICAT I O N
The SBF -1 is a solid state breaker failure
detection relay with contact output. It is used in
conjunction with the primary and backup relays.
Other logic inputs (such as the 52a contact) may
be used where the fault current is insufficient to
operate the current detector.
The relay is applicable with any of the
bus/breaker schemes in general use.
Provision is included in the relay for "retrip
ping" the breaker without time delay. This may
avoid clearing a bus during incorrect maintenance
procedure or due to the failure of a trip contact to
close.
C O N STRUCTION
The SBF-1 Relay consists of a phase and
ground current detector, a breaker failure timer, a
control timer, a seal-in
(X)
relay and an output
relay (AR) along with 2 indicating contactor
switches (ICS).
Overcurrent Detector
The detector consists o f 3 or 4 input
transformers and a plug in m odule. The primary of
the transformer is tapped and brought out to a tap
block located on the front of the relay. Each
transformer has three taps which cover the range
of pickup.
The secondary of the transformers are con
nected to the input of the plug-in detector m odule
where the phase and ground signals are connected
to separate pickup level adjustments located on the
front of the module. A comparator circuit consists
of a plug-in operational amplifer whose output is
connected to logic circuitry which controls the A R
output relay.
Also located on the module is a reed relay
( RR) which is controlled by the breaker failure
(BF) timer on the timer module. The normally
open contacts of the reed relay are connected in the
current detector circuit and controls the operation
of the circuit.
B F and Control Timer
These timers are located on the timer plug-in
module.
The BF timer can be continuously varied over
the range by means of an adjusting knob located at
the front of the module. A calibrated scale permits
setting the desired time delay. A test jack is also
located at the front if it is desired to check the set
ting with an electronic test timer.
At the bottom of the front plate is an access
hole which permits adjusting the control timer
I// {)()lsih/e conringencies
11·hich mar arise during installation. operation. or maintenance. and all
derai/1 and 1ariarinm of
rhis equipmenr do not purport to be covered h1· these instructions. !/further
in/nml!lrinn is desired h1·
r)[lrcha.1er regarding his particular instal/arion. operation or maintenance of
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cc{lli{JIIICIIr. rhe fond
We.lfinghouse E/ecrric Corporation representati1·e should he contacted.
N EW I NFOR M AT I O N
EFFECTIVE N OVEMBER 1978
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