
124 SEBU8088-06
Maintenance Section
Winding - Test
Visually inspe
ct the water pump for leaks. If any
leaking is observed, replace the water pump seal
or the water pump assembly. Refer to the Service
Manual for the
disassembly and assembly procedure.
Note: Refer to the Service Manual or consult your
Caterpillar
dealer if any repair is needed or any
replacement is needed.
i02903565
Winding - Tes
t
SMCS Code: 4453-081; 4454-081; 4457-081;
4470-081
g01445
763
Illustration 78
PMPE generator wiring diagram
(1) Volt
age regulator and/or related com ponents
(CR1) Di
ode
(CR2) Di
ode
(CR3) Di
ode
(CR4) Di
ode
(CR5) Dio
de
(CR6) Dio
de
(CR7) Var
istor
(L1) Exci
ter field (stator)
(L2) Exci
ter a rmature (rot o r)
(L3) M ain fi
eld (rotor)
(L4) Main a
rmature (stator)
(L5) Pilot
exciter armature
(PM) Perma
nent magnet
(RFA) Rotat
ing field assembly
(CST) Custo
mer supplied transformer
Table 18
Tools Needed
Part Number Part
(1)
Quantity
6V-7070
Digital
Multimeter
1
146-4080
Digital
Multimeter
(RS232)
1
(1)
Only one multimeter is necessary for this test. Either of the
multimeters that are s hown will work.
The high voltage that is produced by an operating
generator set can cause severe injury or death.
Before performing any maintenance or repairs,
ensure that the generator will not start.
Place the engine control switch in the “OFF” posi-
tion. Attach “DO NOT OPERATE” tags to all start-
ing controls. Disconnect the batteries or disable
the starting system. Loc k out all switchgear and
automatic transfer switches that are associated
with the generator.
Measure the resistance of the following windings:
(L1), (L2), (L3), (L4), and (L5). The winding that
is being tested must be disconnected from the
other components before the resistance can be
measured. The following resistance measurements
are approximations. If the measured value is
not near the listed approximation, the winding is
probably damaged. For a more precise resistance
value, consult the Technical Marketing Information
(TMI). Refer to the generator arrangement that is in
question.
Note: The winding temperature affects the
resistance. When the winding temperature increases,
the winding resistance also increases. When
the winding temperature decreases, the winding
resistance also decreases. Therefore, a correct
measurement can be performed only when the
winding is at room temperature.
The following armature windings have very little
resistance: (L2), (L4), and (L5). The resistance of
these windings will measure near 0 ohms. Use a
milliohmmeter to measure the resistance of the
armature windings.
Exciter armature (rotor) – less than 0.1 ohm
Main armature (stator) – less than 0.1 ohm
Pilot exciter armature (L5) – less than 0.1 ohm
Use a multimeter in order to measure the resistance
of field windings (L1) and (L3).