Westinghouse KC-4, Инструкция по установке, эксплуатации и обслуживанию

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time out first since it is always set for a shorter
delay. The output of the BF timer is connected to
terminal 9 of the timer module which is wired to
terminal 2 of the overcurrent detector module.
Since operation of the BF timer is indicated by a
voltage drop to less than 2 .5V, transistor Q 1 turns
off and transistor Q2 turns on to pickup the reed
relay ( RR). I n addition, the output of the B F timer
also supplies one of the two inputs to transistor Q5
which controls the A R relay switching transistor
(Q6). The other input controlling transistor Q5 is
either the 52a contact input (if used) connected to
relay terminal 1 8 or operation of the overcurrent
unit circuit. This is obtained when the reed relay
operates to remove the 1 00 ohm resistor ( R 1 9)
from capacitor C 1 and to apply the input current
0
signal to terminal 4 of the IC 1 on the overcurrent
detector module. If this signal voltage is higher
than the reference voltage at terminal 5 of IC 1 the
output voltage at terminal 1 0 (of IC 1 ) will drop
from its high state to less than 2.5 volts. This out­
put change is then applied to the transistor logic
circuit consisting of transistor Q3, Q4 and Q5 (on
the timer module).
C H ARACTERISTICS
Overcurrent Detector
The overcurrent detector has a range of 0. 5 to
1 3 .5 amperes. This is obtained by means of three
tap settings in conj unction with the tap m ultiplier
to give a continuous adj ustment over- the range.
The pickup point is determined by m ultiplying the
tap value by the tap multiplier setting. The operate
speed varies from 3 ms to 8 ms. The reset time is 3
ms maximum and would be measured as the time
for the secondary voltage to decay to 10 volts peak
(with the reed relay R R contacts open). This reset
time applies whether the input current is reduced
to zero or up to 95% of pickup current.
Continuous rating is 10 amperes. One second
rating is 250 amperes.
The accuracy o f the pickup setting is 5% over
the full range and 1 0% from -20 to + 5 5 ° C . Since
the setting is continously adjustable, closer setting
accuracy can be obtained by using a current source
and a precision ammeter.
I.
L.
41 -776.5A
CAUTION: Since the tap block connector screw
carries operating current, be sure that the screw
is turned tight.
I n order to avoid opening the cu rrent
transformer circuits when changing taps under
load, connect the spare tap screw in the desired tap
position before removing the other tap screw from
the original tap position.
Control Timer
The range of the control timer is 1 50 to 250 ms.
The timer as received should be set for ap-
0
proximately 200 ms. A 1 50 to 600 ms timer is
available and is shipped set at 600 ms.
The timer setting can be changed by means of a
screwdriver through the hole on the front plate of
the timer module.
The accuracy is 5% over the temperature and
voltage range.
BF Timer
0
The range of the BF timer is 1 8 to 1 75 ms. It
is set by means of a knob and calibrated scale at
the front of the timer module. A 50 to 500 ms
timer is also available.
The accuracy of the pickup setting is 5%. Since
the setting is continuously adjustable, the timer
may be set closer by instrumentation.
The accuracy is 5% over the temperature and
voltage range.
Power Supply
_Consists of a 10 watt zener diode (Zs), a
res1stor ( Rs) and provides a regulated voltage of
24Vdc ± 1 0% over the voltage and temperature
range. A capaci�or C3 is connected across the
zener diode to decrease the rate of rise and fall of
the output voltage to reduce transient effects.
Both modules and the telephone relay (X) are
energized by the power supply.
Temperature and Voltage
The relay is operative over a range of 80 to
1 1 0% of rated voltage and from -20 to + 5 5 ° C .
3
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