Bryant ASPAS1BBA007, Diagnostic Repair Manual

Page: 64 / 144

Page 64
SECTION 3.4
DIAGNOSTIC TESTS
PART 3
“V-TYPE” PREPACKAGED
TRANSFER SWITCHES
using whatever means provided (such as a utility source
main line breaker).
DANGER: DO NOT ATTEMPT MANUAL
TRANSFER SWITCH OPERATION UNTIL ALL
POWER VOLTAGE SUPPLIES TO THE
SWITCH HAVE BEEN POSITIVELY TURNED
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
transfer 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
operating 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
contacts (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
voltage 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 su12 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
connected to Wire 23. Positive 12VDC 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
terminal strip in the transfer switch.
a. If voltage is present, proceed to Step 5.
b. If voltage is not present, proceed to Step 9.