Filter
Top Products
TRANSFER SWITCH
SECTION 3.4
DIAGNOSTIC TESTS
PART 3
Page 75
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 voltage
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, refer to
Flow Chart.
TEST 27 – 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 seconds), the
transfer relay should energize to deliver utility source
power to the standby closing coil terminals. 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
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 2. 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.
Figure 2. Manual Transfer Switch Operation
MANUAL
TRANSFER
HANDLE
TRANSFER
SWITCH
OPERATING
LEVER
MANUAL
TRANSFER
HANDLE
TRANSFER
SWITCH
OPERATING
LEVER
LOAD CONNECTED TO
UTILITY POWER SOURCE
LOAD CONNECTED TO
STANDBY POWER SOURCE