______________________________________________________________________________________
EA42-7
5
● Slowly adjust the regulator voltage adjust V until
the generator output voltage reaches the nominal
value. Should a low frequency oscillation or
hunting be present on the generator output
voltage, adjust stability control S to cause this to
be damped out. In general, “ Clockwise ”
increases the stability but in some cases, too far
CW may start to reduce stability again, and will
invariably slow the response of the generator to
load changes. An optimum method of setting is to
adjust S slowly CCW until the generator voltage
just starts to become unstable, then up to 1/4 turn
CW from that position.
● If used, adjust the external voltage adjust
rheostat to fine trim the voltage to the exact value
desired.
RESULT :
Voltage should now have built up and be stable at the
desired value. If voltage does not build to rated value,
check that there is no short circuit or excessive load
present on the generator lines. If a minimum residual
of 5
Vac is not present, perform “ field flashing ” per
paragraph 3.4.
● Check regulator under normal operating and
loading conditions.
RESULT :
Voltage regulation should be better than
1.0%
no-load to full-load. If regulation is not within this range,
check the following :
1. Voltage reduction under loads of cos
0.0
may be due to speed reduction due to loading of
the prime mover. This may be causing the
frequency compensation (V/Hz) circuit to reduce
voltage at a speed which is less than the “ corner
frequency ”.
2. Replace voltage regulator.
3.4 Field Flashing
When the regulator is operated with the generator for
the first time, the polarity of residual magnetism may
be reversed or too small to achieve the necessary
build-up voltage for the regulator. If reversing the field
connections does not induce build-up, and the residual
voltage is less than the specified value of 5 Vac, shut
down the Prime-mover and proceed with the following
steps :
● With the Prime-mover at rest and the regulator’s
field output wires disconnected, apply a DC
source ( NOT grounded ) of not more than 3~12
Vdc with Positive to F+ and Negative to F-, in
series with a current-limiting resistor of 3~5 ohms
20 watt. (The set battery is a suitable source.)
● Allow approximately 3 seconds before removing
the DC source.
● With the voltage regulator disconnected ( wires 3
and 4 ), start the prime mover and measure the
“ residual ” voltage available at the auxiliary
winding. If this voltage is greater than 5 Vac,
reconnect voltage regulator, and voltage build-up
should be successful. If less than 5 Vac is
measured, repeat field flashing procedure.
● If repeating steps a. and b. does not result in
generator voltage build-up, and residual is
greater than 5 Vac, replace voltage regulator.
C
T
D
N
STAB.
U/F
VOLT
B
A
P
50
Q
50
LINK FOR LARGER TIME CONSTANTS
LINK TO DISABLE OVER-EXCITATION SHUTDOWN
DROOP ADJUST
RHEOSTAT
(5 OHMS, 10W)
C.T.
(N:1A)
GENERATOR
50/60HZ
FIELD
+
-
AUXILIARY
WINDING
5A 240 V FUSE
-
+
4
3
V
Y
X
U
GROUND CONNECTION
LINK FOR 50HZ
EXT. VOLTS
LINK IF EXT. VOLTS ADJUST NOT REQUIRED
U
V
W
N
ADJUST