TROUBLESHOOTING
TESTING AND ADJUSTING
POSSIBLE CAUSES
VERIFICATION PROCEDURE
(Continued)
Remove the load from the generator by either opening the line
circuit breaker or the load connections to (T1), (T2), (T3) and
(T0). Separate stator (L6) from the regulator assembly by
removing wires (20, 22, 24 and 26) from terminals (20, 22, 24 and
26). If neutral cable (T0) is connected to the generator frame or
ground, open the connection. Use a megohmeter and measure the
resistance of the insulation from each lead (T1 thru T0) of the
stator winding to ground. Generators that are rated 600 volts or
less must have a resistance of one megohm or more. Generators
rated 2400 volts or higher must have a resistance of three
megohms or more.
9.
Loose Wire Connections
Visually check for loose or broken wires and connections. Check
the wires and connections on the regulator assembly, the rotating
rectifiers (CR1 thru CR6), and heat sinks (E1) and (E2).
10. Wrong Regulator or Generator
Make a comparison of the generator line cable connections with
Connections
those shown on the generator name plate. Check wiring of the
regulator assembly and revolving field assembly (RFA) against the
wiring diagram.
11. Shorted Rotating Rectifiers
Remove the connection between rotating field (L5) and either
(CR1 thru CR6)
heat sink (E1) or (E2). NOTE: It is not necessary to remove both
connections. The rotating rectifiers can be checked in groups of
three, (CR1, CR2 and CR3) or (CR4, CR5 and CR6). Use an
ohmmeter or 8S4627 Continuity Tester. NOTE: When using the
8S4627 Continuity Tester, the clip is the negative polarity
terminal and the probe is the positive polarity terminal. The
instructions on the tester label are not correct. Connect the
positive cable to heat sink (E1) and the negative cable to terminal
connection of either (CR1, CR2 or CR3). The ohmmeter must be
on the RX1000 scale. A very high resistance on the ohmmeter
scale or no light with the continuity tester must be the result.
Check the second group of rectifiers (CR4, CR5 and CR6).
Connect the positive cable of the ohmmeter or continuity tester to
the terminal connector of either (CR4, CR5 or CR6) and the
negative cable to heat sink (E2). A very high resistance indication
on ohmmeter scale (RX1000) or no light on the continuity tester
must be the result.
NOTE
If the test for high resistance or no light is not according
to the description above, one or more of the rectifiers is shorted.
To find the rectifier that is shorted it is necessary that each one be
tested separately. Remove the wires bolted to the rectifier
separately. For more information, see TESTING POWER RECTI-
FIERS AND CONTROLLED RECTIFIERS.
12. Shorted Circuit in Field
Disconnect field rectifier (CR10) by removing wire (8) from spade
Rectifier (CR10)
terminal (8) of rectifier module (A2). Check reverse resistance of
field rectifier (CR10) with an ohmmeter or continuity tester
(8S4627). Connect the positive cable of the ohmmeter or
continuity tester on spade terminal (8) and the negative cable on
spade terminal (6). Typical reverse resistance is 30.000 ohms or
more. NOTE: Field rectifier (CR10) is in parallel with a
resistance-capacitance circuit inside rectifier module (A2). When
the ohmmeter test cables are first connected to the circuit, a low
(Continued on next page)
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