Terex T25I and T45I Super Quiet Generator 27
Operating Instructions and Parts Manual
June 2006
REV A
ELECTRICAL
TROUBLESHOOTING
5 COMPONENTS THAT CAUSE
VOLTAGE RELATED PROBLEMS
POTENTIOMETER
Connects to voltage regulator. Bypass potentiom-
eter by unplugging from voltage regulator and
installing jumper on 2 male spades on regulator.
VOLTAGE REGULATOR
(Located inside the upper control panel behind the
gauges.)
Measure DC voltage at F1 & F2. Normal voltage is
10 to 12 V DC. Remove 2 wires marked (F1,
X)(F2, X X) from voltage regulator. Connect wire
marked F1 to positive and F2 to negative of a 12
volt battery. Start unit and measure voltage. If unit
produces close to maximum output, replace
Automatic Voltage Regulator.
VOLTAGE SELECTOR SWITCH
The correct way to test is to disconnect from
generator and hard wire the generator into one
configuration. This will eliminate the switch from
the circuit and verify that the generator is function-
ing properly. All contacts should be checked
following the proper schematic with the switch
disconnected from the generator set. Actual loads
can cause failures in contacts that cannot be
duplicated using a meter.
OVERCURRENT RELAY
This device causes the 3-phase breaker to trip
that supplies AC power to the distribution lugs if
uneven or excessive current is measured at the
distribution lugs. It is also connected to the 3-
phase door switch and will automatically trip the 3-
phase breaker when the door is open and pre-
vents the breaker from being reset while it is open.
GENERATOR
Test resistance of field, stator and exciter wind-
ings. Contact TEREX for procedures or repair
facility recommended by generator manufacturer.
PROCEDURE FOR TESTING
GENERATOR WITH NO OUTPUT
THIS EQUIPMENT USES HIGH VOLTAGE
CIRCUITS CAPABLE OF CAUSING SERIOUS
INJURY OR DEATH! EXCERCISE EXTREME
CAUTION AROUND ANY ELECTRICAL
COMPONENT WHEN OPERATING THIS UNIT.
IT IS ESSENTIAL THAT ALL TEST INSTRU-
MENTS ARE REGULARLY CHECKED FOR
SAFETY, AND ANY CONNECTION LEADS,
PROBES, OR CLIPS, ARE CHECKED TO
ENSURE THAT THEY ARE SUITABLE FOR
THE VOLTAGE LEVELS BEING TESTED.
NEVER ATTEMPT TO TEST A "LIVE" GENERA-
TOR UNLESS THERE IS ANOTHER COMPE-
TENT PERSON PRESENT WHO CAN SWITCH
OFF THE POWER SUPPLY OR SHUT DOWN
THE ENGINE IN AN EMERGENCY.
NEVER EXPOSE "LIVE" CONNECTIONS UN-
LESS YOU HAVE CREATED A SAFE WORKING
AREA AROUND YOU. MAKE SURE YOU HAVE
MADE ALL OTHER PERSONS IN THE IMMEDI-
ATE AREA FULLY AWARE OF WHAT YOU
ARE DOING.
• When a new generator is not producing voltage,
the testing or wiring personnel should first verify
that the unit is wired correctly! The stack switch
and generator leads should all be checked as
well as the breaker and sensing leads. If the
unit was not wired correctly and you flashed the
generator, you could burn up the unit. (Do not
forget to check the sensing leads!).
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