Table of Contents
Advertisement
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
milli seconds longer than the B F timer. This allows
for
pickup time of the reed relay
relay
pickup (3 to 5 ms) and operate time of the
o / c
unit (3 to 8 ms).
The range of adjustment is a minimum of 1 00
0
ms ( 1 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 m s .
The control timer acts essentially a s 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 o f the
timer m odule permits setting the time delay from
1 8 to 17 5 milliseconds. The scale is calibrated in 25
ms increments. If more accurate settings are
desired an oscilloscope or electronic timer may be
connected between the upper red test jack on the
timer m odule 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 5 0 t o 500 m s B F timer with 5 0 m s scale
increments is also available.
A locking tab is provided to h old 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
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 m argin for the SBF-1
is
( I
to 3 ms), A R
I N DI CATI N G C O NTACTOR
SWITC H ( I C S)
block to the desired setting by means of the con
nect ing screw .
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.
panels or their equivalent i n a l ocation free from
dirt, m oisture, excessive vibration and heat.
M ount 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 h oles 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 u se in the locations shown on the out
line and drilling plan to facilitate making a good
electrical connection between t he relay case, its
m ounting screws or studs, and the relay panel.
Ground wires are affixed to the mounting screws
or studs as required for poorly grounded or in
sulating panels. Other electrical connections may
be m ade directly to the terminals by means o f
screws f o r steel panel mounting or to 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.
I . L. 4 1 -076.
operation of this relay h ave been m ade at the fac
tory and should not be disturbed.
2
cycles . (33 ms)
Connect the lead located in front of the tap
When the relay energizes a 1 25 or 250 V de type
I N STALLATION
The relays should be mounted on switchboard
For detail information on the FT case refer to
ADJU STM E NTS A N D
MAI NTENANCE
The proper adjustment to insure correct
I. L. 41-776.5A
5
Advertisement
Table of Contents
