Guardian 4389 Repair Manual page 65

"V-TYPE" PREPACKAGED
TRANSFER SWITCHES
e. Set the generator AUTO-OFF-MANUAL switch
to AUTO.
(1) The generator should crank and start.
(2) When the generator starts, an "engine
warm-up timer" should start timing. After
about 15 seconds, the transfer relay should
energize and transfer to the "Standby"
source should occur.
f. If transfer to "Standby" does NOT occur, check
the voltage across transfer switch Terminal
Lugs E1 and E2. The generator line-to-line volt-
age should be indicated.
RESULTS:
1. If normal transfer to "Standby" occurs, discontinue tests.
2. If transfer to "Standby" does NOT occur and no voltage
is indicated across Terminal Lugs E1/E2, determine why
generator AC output has failed.
3. If transfer to "Standby" does NOT occur and voltage
reading across Terminal Lugs E1/E2 is good, go on to
Test 22.
TEST 22 - CHECK VOLTAGE AT STANDBY
CLOSING COIL C2
DISCUSSION:
Standby source voltage is used to energize the stand-
by closing coil and actuate the main contacts to their
"Standby" source side. Standby source alternating
current (AC) is changed to direct current (DC) by a
bridge rectifier before reaching the closing coil. This
test will determine if
voltage is available to the closing coil.
If normal source voltage is available to the terminals
of the closing coil but transfer to "Standby" does not
occur, look for (a) binding or sticking in the transfer
mechanism, (b) a defective coil, or (c) a bad bridge
rectifier. The coil and the bridge rectifier must be
replaced as a unit.
PROCEDURE:
1. Set the generator main line circuit breaker to the OFF or
"Open" position.
2. Set the generators AUTO-OFF-MANUAL switch to the
OFF position.
3. Set your VOM to measure AC voltage.
DANGER: BE CAREFUL! HIGH AND DANGER-
!
OUS VOLTAGES ARE PRESENT AT TERMI-
NAL LUGS WHEN THE GENERATOR IS RUN-
NING. AVOID CONTACT WITH HIGH VOLT-
AGE TERMINALS OR DANGEROUS AND POS-
SIBLY LETHAL ELECTRICAL SHOCK MAY
RESULT. DO NOT PERFORM THIS VOLTAGE
TEST WHILE STANDING ON WET OR DAMP
PART 3
GROUND, WHILE BAREFOOT, OR WHILE
HANDS OR FEET ARE WET.
4. Disconnect Wire E2 from the standby closing coil (C2).
Connect one meter test Lead to Wire E2. Use a suitable
and safe connection to this wire, such as an alligator
clip that attaches to the meter test probe. Isolate this
wire and test probe from any other potential source or
ground.
5. If necessary, repeat Step 2 under "Procedure" of Test
21. The system must be in automatic operating mode,
with engine running, and standby source voltage avail-
able to Terminal Lugs E1 and E2.
6. Locate on the standby closing coil the terminal that Wire
B is connected to. (Figure 1, previous page). Connect
the other meter test lead to this terminal. Generator line
to line voltage should be indicated. If generator voltage
is NOT indicated, proceed to Step 7.
7. With Wire E2 still connected to one test probe, connect
the other meter test lead to Wire 205 on Limit Switch
XB1(see Figure 1 on previous page). Generator line to
line voltage should be measured.
RESULTS:
1. If generator line-to-line voltage is indicated in
"Procedure, Step 6," but transfer does NOT occur, pro-
ceed to Test 24.
2. If generator line-to-line voltage is NOT indicated in
"Procedure, Step 7," proceed to Test 33.
3. If generator line-to-line voltage is indicated in
"Procedure, Step 7," proceed to Test 25.
TEST 23 - TEST TRANSFER RELAY TR
DISCUSSION:
In automatic operating mode, the transfer relay must
be energized by circuit board action or standby
source power will not be available to the standby
closing coil. Without standby source power, the clos-
ing coil will remain de-energized and transfer to
"Standby" will not occur. This test will determine if the
transfer relay is functioning normally.
PROCEDURE:
1. See Figure 2. Disconnect all wires from the transfer
relay, to prevent interaction.
2. Set a VOM to its "R x 1" scale and zero the meter.
3. Connect the VOM test leads across Relay Terminals 6
and 9 with the relay de-energized. The VOM should
read INFINITY.
SECTION 3.4
DIAGNOSTIC TESTS
Page 63