Guardian 4721, Руководство по ремонту

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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 1 - 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.
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’s main circuit breaker. The circuit breaker must be set
to its ON or “Closed” position. When you are sure the generator’s
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’s 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
transfer 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. See Part 5 for manual operating procedures.
d. Actuate the generator’s main line circuit breaker
to its ON or “Closed” position. The “Utility”
power supply to the transfer switch must be
turned OFF.
e. Set the generator’s 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’s 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 read-
ing across Terminal Lugs E1/E2 is good, go on to Test 2.
Figure 1. The “V-Type” Transfer Mechanism
TEST 2- 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
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
B E2
!
PART 3
Page 50
“V-TYPE” PREPACKAGED
TRANSFER SWITCHES
SECTION 3.4
DIAGNOSTIC TESTS