“V-TYPE” PREPACKAGED
TRANSFER SWITCHES
SECTION 3.4
DIAGNOSTIC TESTS
PART 3
Page 69
OFF. FAILURE TO TURN OFF ALL POWER
VOLTAGE SUPPLIES MAY RESULT IN
EXTREMELY HAZARDOUS AND POSSIBLY
LETHAL ELECTRICAL SHOCK.
4. In the transfer switch enclosure, locate the manual trans-
fer handle. Handle is retained in the enclosure with a
wing nut. Remove the wing nut and handle.
5. See Figure 3. Insert the un-insulated end of the handle
over the transfer switch operating lever.
a.Move the transfer switch operating lever up to
actuate the load contacts to the Utility position,
i.e., load connected to the utility source.
b. Actuate the operating lever down to move the
load contacts against the standby contacts, i.e.,
load connected to the Standby source.
6. Repeat Step 5 several times. As the transfer switch oper-
ating lever is moved slight force should be needed until
the lever reaches its center position. As the lever moves
past its center position, an over-center spring should
snap the moveable load contacts against the stationary
STANDBY
or UTILITY contacts.
7. Finally, actuate the main contacts to their UTILITY power
source side, i.e., load contacts against the UTILITY con-
tacts (upward movement of the operating lever).
RESULTS:
1. If there is no evidence of binding, sticking, excessive
force required, replace the appropriate closing coil.
2. If evidence of sticking, binding, excessive force required
to move main contacts, find cause of binding or sticking
and repair or replace damaged part(s).
TEST 25- TEST LIMIT SWITCH XB1
DISCUSSION:
Standby power source voltage must be available
to the standby closing coil in order for a transfer to
standby action to occur. To deliver that source volt-
age to the coil, limit switch XB1 must be closed to the
“Standby” power source side. If the limit switch did not
get actuated or has failed open, the source voltage
will not be available to the closing coil and transfer to
“Standby” will not occur.
PROCEDURE:
With the generator shut down, the generator main
circuit breaker turned OFF, and with the utility power
supply to the transfer switch turned OFF, test limit
switch XB1 as follows:
1. To prevent interaction, disconnect Wire 205 and Wire B
from the limit switch terminals.
2. Set a VOM to its “R x 1” scale and zero the meter.
3. See Figure 1. Connect the VOM test probes across
the two outer terminals from which the wires were
disconnected.
4. Manually actuate the main contacts to their “Standby”
position. The meter should read INFINITY.
5. Manually actuate the main contacts to their UTILITY
position. The meter should read CONTINUITY.
6. Repeat Steps 4 and 5 several times and verify the VOM
reading at each switch position.
RESULTS:
1. If Limit Switch XB1 fails the test, remove and replace the
switch or adjust switch until it is actuated properly.
2. If limit switch is good, repair or replace Wire B between
limit switch and Standby Coil (C2).
TEST 26 - CHECK 23 AND 194 WIRING/
CONNECTIONS
DISCUSSION:
An open circuit in the transfer switch control wiring
can prevent a transfer action from occurring. In the
auto mode, the circuit board supplies +12 VDC to
Wire 194. This DC voltage is supplied to the transfer
relay (TR) at Terminal Location “A”. The opposite
side of the transfer relay (TR) coil (Terminal B) is con-
nected to Wire 23. Positive 12 VDC is present on this
also. Circuit board action will allow current to flow
through the circuit and the (TR) is energized.
PROCEDURE/RESULTS:
1. Set VOM to DC volts
2. Place generator AUTO-OFF-MANUAL switch to the
AUTO position. Utility power should be present; the
generator should not start.
3. Connect the negative (-) test lead to a suitable frame
ground in the transfer switch.
4. Connect the positive (+) test lead to Wire 194 at the ter-
minal strip in the transfer switch.
a.If voltage is present, proceed to Step 5.
b. If voltage is not present, proceed to Step 9.
5. Connect the positive (+) test lead to Wire 23 at the termi-
nal strip in the transfer switch.
a.If voltage is present, proceed to Step 6.
b. If voltage is not present, repair wiring between
terminal strip and transfer relay (TR).
6. Connect the negative (-) test lead to the ground lug in
the generator control panel. Connect the positive (+)
test lead to Wire 23 in the generator control panel at the
interconnection terminals (ICT) or at the terminal strip.
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