Guardian 4389 Repair Manual page 66

SECTION 3.4
DIAGNOSTIC TESTS
CONNECT VOM
TEST LEADS ACROSS
Terminals 6 and 9
Terminals 1 and 7
4. Using jumper wires, connect the positive (+) post of a 12
volt battery to relay Terminal "A" and the negative (-)
battery post to Relay Terminal "B". The relay should
energize and the VOM should read CONTINUITY.
N1A
194
Figure 2. Transfer Relay Test Points
5. Now, connect the VOM test leads across Relay
Terminals 1 and 7.
a. Energize the relay and the meter should indi-
cate INFINITY.
b. De-energize the relay and the VOM should read
CONTINUITY.
LOAD CONNECTED TO
UTILITY POWER SOURCE
Page 64
DESIRED METER READING
ENERGIZED DE-ENERGIZED
Continuity Infinity
Infinity Continuity
126 205
E1
23
MANUAL
TRANSFER
HANDLE
TRANSFER
SWITCH
OPERATING
LEVER
Figure 3. Manual Transfer Switch Operation
PART 3
RESULTS:
1. Replace transfer relay if it is defective.
2. If transfer relay checks good go to Test 26.
TEST 24- CHECK MANUAL TRANSFER
SWITCH OPERATION
DISCUSSION:
In automatic operating mode, when utility source volt-
age drops below a preset level, the engine should
crank and start. On engine startup, an "engine warm-
up timer" on the generator circuit board should start
timing. When that timer has timed out (about 15 sec-
onds), the transfer relay should energize to deliver
utility source power to the standby closing coil termi-
nals. If normal utility source voltage is available to the
standby closing coil terminals, but transfer to Standby
does not occur, the cause of the failure may be (a) a
failed standby closing coil and/or bridge rectifier, or
(b) a seized or sticking actuating coil or load contact.
This test will help you evaluate whether any sticking
or binding is present in the transfer mechanism.
PROCEDURE:
1. With the generator shut down, set the generator AUTO-
OFF-MANUAL switch to OFF.
2. Set the generator main circuit breaker to OFF or "Open".
3. Turn off the utility power supply to the transfer switch,
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
LOAD CONNECTED TO
STANDBY POWER SOURCE
"V-TYPE" PREPACKAGED
TRANSFER SWITCHES
TRANSFER
SWITCH
OPERATING
LEVER
MANUAL
TRANSFER
HANDLE