GENERAL
Test numbers in this section correspond to the num-
bered tests in Section 3.3, “Troubleshooting Flow
Charts”. When troubleshooting, first identify the
problem. Then, perform the diagnostic tests in the
sequence given in the flow charts.
TEST 21 - CHECK VOLTAGE AT TERMINAL
LUGS E1, E2
DISCUSSION:
In automatic mode, the standby closing coil (C2) must
be energized by standby generator output if transfer to
the “Standby” source is to occur. Transfer to “Standby”
cannot occur unless that power supply is available to
the transfer switch.
DANGER: BE CAREFUL! HIGH AND
DANGEROUS VOLTAGES ARE PRESENT
AT TERMINAL LUGS E1 AND E2 WHEN
THE GENERATOR IS RUNNING. AVOID
CONTACT WITH HIGH VOLTAGE TERMINALS
OR DANGEROUS AND POSSIBLY LETHAL
ELECTRICAL SHOCK MAY RESULT. DO
NOT PERFORM THIS VOLTAGE TEST WHILE
STANDING ON WET OR DAMP GROUND,
WHILE BAREFOOT, OR WHILE HANDS OR
FEET ARE WET.
PROCEDURE:
1. If the generator engine has started automatically (due to
a utility power source outage) and is running, check the
position of the generator main circuit breaker. The circuit
breaker must be set to its “On” or “Closed” position. When
you are sure the generator main circuit breaker is set to
ON (or closed), check the voltage at transfer mechanism
Terminal Lugs E1 and E2 with an accurate AC voltmeter
or with an accurate volt-ohm-milliammeter (VOM). The
generator line-to line voltage should be indicated.
2. If the generator has been shut down, proceed as follows:
a.On the generator control panel, set the AUTO-
OFF-MANUAL switch to OFF.
b. Turn off all power voltage supplies to the trans-
fer switch. Both the utility and standby power
supplies must be positively turned off before
proceeding.
c. Check the position of the transfer mechanism
main contacts. The moveable LOAD contacts
must be connected to the stationary UTILITY
source contacts. If necessary, manually actuate
the main contacts to the “Utility” power source
side.
d.Actuate the generator main line circuit breaker
to its “On” or “Closed” position. The utility power
supply to the transfer switch must be turned off.
Figure 1. The “V-Type” Transfer Mechanism
UTILITY
CLOSING
COIL (C1)
STANDBY
CLOSING
COIL (C2)
BRIDGE
RECTIFIER
BRIDGE
RECTIFIER
MANUAL
TRANSFER
LEVER
LIMIT
SWITCH
(XA1)
N1
N2
E2
E1
T1
LIMIT
SWITCH
(XB1)
T2
N2A A
A
B
126
205
B
E2
PART 3
Page 66
“V-TYPE” PREPACKAGED
TRANSFER SWITCHES
SECTION 3.4
DIAGNOSTIC TESTS
To Next Page
