| |
Back
Generator Maintenance | Up
Construction Mechanic Basic Volume 02 - Construction methods and practices | Next
Armature Test |
Figure 2-15.—Disassembled view of a two-brush generator.
TESTING FIELD COILS.—To
test
the
generator field, you must disconnect the grounded
ends from the frame. Place one probe of the test lamp
circuit on the field terminal end of the coils and the
other probe on the grounded end. If the lamp lights, the
field circuit is complete. However, because of the
resistance in the field coil wire, it should not bum with
normal brilliancy. Normal brilliancy of the test light
bulb indicates a possible short circuit between the coils
of the field. If the light does not burn, the field is open-
circuited.
A grounded field coil is located by placing one test
probe on the field terminal and the other on the
Figure 2-16.—Testing field coils for ground. CMB2F169
generator frame (fig. 2-16). If the test lamp lights, the
field is grounded. The ground may be caused by frayed
wires at the coil ends. In most cases, grounds and open
field coil ends, the ohmmeter will measure the actual
circuits in the field coils cannot be satisfactorily
resistance of the coil. If the specified resistance of a
repaired. The defective field coil must then be
field coil is given in the manufacturer’s manual, also
replaced.
obtained by measuring a new coil, you can compare
values obtained through tests. For example, a short-
Test for grounds, shorts, and open circuits in the
circuited field coil would have practically no
field coils can also be made with an ohmmeter. The
resistance and the ohmmeter would register near zero;
ohmmeter has test probes similar to the test lamp
or the ohmmeter would register excessively high
circuit. When these test probes are connected to the
resistance in testing a coil having an open circuit. By
2-15
|
