Westerbeke W-27 Service Manual

BT GENERATOR TROUBLESHOOTING
NOTE: The following is a list offaults with the generator operation on compound (COMP) transformer
regulation (no A.
V.R. installed).
FAULT
CAUSE
CORRECTION
Low Voltage (70 vo~s) at NIL and loss of 1. Selector switch in wrong position. 1. Place selector switch in COMP position.
voltage as load is applied (no loss of engine
speed and hertz).
High voltage at NIL (125 - 135 volts) with 1. Generator's engine speed (rpm) high at NIL 1. Check NIL speed and adjust NIL voltage.
correct voltage when loaded
(115 -120 volts).
High voltage at NIL and F/L. 1. Generator's engine speed (rpm) high.
1. Check NIL rpm and adjust NIL voltage.
2. Short in compound transformer auxiliary 2. Check continuity and connections of 0-3 windings.
windings 0-3.
low voltage at Nil (0 - 5 volts) with
1. Main stator windings shorted C-1, C-2. 1. Check continuity and resistance values of C-1 , C-2 windings
growling noise from generator and loss of
and connections. Excite unit with 12 VOC.
engine speed when load is applied.
2. Compound transformer windings shorted 2. Check continuity and resistance values of 0-1, 0-2 windings.
0-1, 0-2. Excite unit with 12 VOC.
Generator does not excite; voltage is 1. Generator's engine speed (rpm) is slow.
1. Adjust the engine's speed and adjust NIL voltage.
o volts at NIl.
2. Short in the main stator windings or 2. Excite the unit with 12 VDC. Short will appear as a
in transformer. load on the engine, growling of the generator.
3. Failed diodes on exciter rotor. 3. Check the diodes on the exciter rotor. Four or more
failed diodes will terminate the rotating field.
4. Shorted pozi-resistor. 4. Visually examine the pozi-resistor on the exciter rotor. The
shorted resistor will be burnt. This will short out the rotating
field. Remove and test run.
low voltage at NIL (10 - 20 volts); when 1. Diodes(s) in rotating exciter (B-2) shorted. 1. Check B-1 and B-2 in the rotating exciter as explained in
load is applied, voltage drops. this manual.
2. Bridge rectifier defective.
2. Follow test procedure for the bridge rectifier.
3. Auxiliary windings B-1 shorted. 3. Check the continuity and resistance values.
4. Auxiliary windings 0-3 andlor C-3 open. 4. Check the continuity and resistance values of windings and
connections.
Voltage correct at NIL, but not at F/l with
. 1. Selector switch in ELEC position. 1. Place selector switch in COMP.
loss of engine rpm (hertz).
2. Exciter stator windings A-1 and A-2 2. Check continuity and resistance values of A-2 windings.
are open.
3. Generator's engine speed is.low. 3. Check generator NIL rpm and adjust NIL voltage.
Voltage correct at NIL, but not at F/L with
1. Generator overload. 1. Check data plate and monitor load on generator with
loss of engine rpm (hertz).
amp-probe.
2. low power factor load (motor loads). 2. Check type of load applied. Consider use of optional.
are open. regulator board.
Unstable voltage.
1. Engine's rpm fluctuating. 1. Check the engine operation and the fuel system.
Low voltage at NIL and voltage drops 1. Diodes in exciter rotor shorted (B-2).
1. Check the diodes in the exciter rotor as illustrated
further as a load is applied.
in this manual.
2. Auxiliary windings in exciter rotor shorted
2. Check the resistance values and continuity to ground.
(B-2).
Voltage OK at Nil and low at F/L. 1. Auxiliary windings in the exciter rotor. 1. Check resistance values and continuity to ground.
2. Exciter stator compound windings A-2 2. Check continuity and connection of windings.
is open.
3. Auxiliary windings 0-3 or C-3 open. 3. Check continuity and connection of windings.
Voltage unstable.
1. Defective regulator board. 1. Check stability of DC voltage from regulator to exciter stator
windings. Operate unit on COMP. Replace regulator board.
2. Engine is hunting. 2. Check engine operation and the fuel system.
3. Electrical connections.
3. Check for clean and secure connections.
Engines & Generators
88

Westerbeke W-27 Specifications

General

Brand	Westerbeke
Model	W-27
Category	Engine
Language	English