Guardian 4389 Repair Manual page 64

SECTION 3.4
DIAGNOSTIC TESTS
GENERAL
Test numbers in this section correspond to the num-
bered tests in Section 3.3, "Troubleshooting Flow
Charts". When troubleshooting, first identify the prob-
lem. 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 DANGER-
!
OUS VOLTAGES ARE PRESENT AT TERMI-
NAL LUGS E1 AND E2 WHEN THE GENERA-
TOR IS RUNNING. AVOID CONTACT WITH
HIGH VOLTAGE TERMINALS OR DANGER-
OUS 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.
BRIDGE
RECTIFIER
UTILITY
CLOSING
COIL (C1)
LIMIT
SWITCH
(XB1)
STANDBY
CLOSING
COIL (C2)
BRIDGE
RECTIFIER
Page 62
N2A
LIMIT
SWITCH
(XA1)
MANUAL
TRANSFER
LEVER
E2
Figure 1. The "V-Type" Transfer Mechanism
PART 3
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 indi-
cated.
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.
A
B
"V-TYPE" PREPACKAGED
TRANSFER SWITCHES
N1
N2
A
126
205
B
E1
E2
T2
T1