ABB KA-4, Instruction Leaflet

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41-923.4M
8
With the moving contact in the normally closed posi-
tion, i.e., against the right side of the bridge, screw in
the stationary contact until both contacts just close.
Then screw in the stationary contact approximately
one-quarter turn farther to provide the correct
amount of follow for KR & TC type carrier, one-half
turn for TA-3 tones.
The clamp holding the stationary contact housing
need not be loosened for the adjustment since the
clamp utilizes a spring-type action in holding the sta-
tionary contact in position.
The sensitivity adjustment is made by varying the
tension of the spiral spring attached to the moving
element assembly. The spring is adjusted by placing
a screwdriver or similar tool into one of the notches
located on the periphery of the spring adjuster and
rotating it. The spring adjuster is located on the
underside of the bridge and is held in place by a
spring type clamp that does not have to be loosened
prior to making the necessary adjustments.
Pass 0.5 amp of ac through relay terminals 16 and
17. Adjust the spring until the contact just opens. In a
similar manner the pick-up value can be adjusted for
any value between .5 and 1.0 amp.
7.1.2. Auxiliary Units (CSP and CSG)
The two contactor switches, CSP and CSG, have
adjustable plunger travel. Adjust the stationary core
and the moving core of 1/64” when the switch is
picked up. This can be done by turning the relay
upside-down and screwing up the core screw of the
switch until the contacts just separate. Then back off
the core screw approximately one turn and lock in
place. This prevents the moving core from striking
and sticking to the stationary core because of resid-
ual magnetism. Adjust the contact clearance for
approximately 1/32” by means of the two small nuts
on either side of the Micarta disc.
Each contactor switch has a section of a tapped
resistor in series with it, and will pick up positively
when rated trip circuit voltages is applied across the
coil and its section of the resistor.
The units should operate at 24 volts for the 48-volt
relay, 60 volts for the 125-volt relay and 120 volts for
250-volt relay. These units have an intermittent rat-
ing, and should not be energized for more than a few
seconds.
7.1.3. Squelch Unit
Check operation with timer. Adjust series resistor to
measure approximately 5000 ohms for 125 Vdc
relays and for 13000 ohms for 250 Vdc relay. With
armature closed, adjust the residual air gap to be
.002” – .003”. Contact gap should measure from
.020” to .035”. Check for dropout time between .140
and .160 seconds. If necessary dropout time can be
adjusted by changing the residual air gap. After final
adjustment the gap should be at lease .002”. The
pickup time should be below 16 milliseconds at -20%
rated dc voltage. If necessary readjust series resis-
tor.
7.1.4. Operation Indicator
The operation indicator should pickup and drop the
indicator target when the current is between 1 and
1.2 amperes dc.
Make sure that the target drops freely when the unit
operates.
7.2. ZENER DIODE TEST
7.2.1. Forward Characteristics
Pass 200 mA of dc current through terminals 8 and 9
with positive on terminal 8. Measure voltage drop
across terminals 8 and 9 with positive on 9. The volt-
age drop should not exceed 3.5 volts.
7.2.2. Reverse Characteristics –
Breakdown Voltage
The breakdown Voltage is determined by increasing
voltage across terminals 8 and 9 with positive on 9.
Place 10,000 ohm resistor in series with ammeter.
Increase voltage until current reads .25 mA. Measure
dc voltage across terminals 8 and 9. The voltage
should be between 160 and 240 volts for 48 and 125
Vdc rated relays; and 320 to 480 volts for 250 Vdc
rated relays.
DO NOT exceed 3.0 mA current in the
circuit.