TM 5-6115-400-35
Ref
Designator
Description
Location
R11
Magamp bias balance
Electric governor
(2) Start engine. If engine hunts, adjust until
adjustment (fre-
control unit
operation is stable. Possible adjustments
quency null
(fig. 132)
are:
adjustment)
(a) If hunt is of high frequency and
R12
Magamp bias level
Electric governor
small amplitude possible cause is
adjustment
control unit
that the magamp bias level is too
R14
Feedback null
Electric governor
high. Adjust R12. counterclockwise
adjustment
control unit
adjustment raises bias level;
R16
Load measurement
Electric governor
clockwise adjustment reduces bias
gain adjustment
control unit
level.
R16
Feedback gain
Electric governor
(b) If hunt is of high frequency and
adjustment
control unit
small amplitude, possible cause
R18
Frequency gain
Electric governor
could be too much feedback again.
adjustment
control unit
Adjust R16. Counterclockwise ad-
R1
Frequency adjust
Generator set
justment decreases gain; clockwise
control panel
adjustment increases gain (c) If
(fig. 180)
hunt is of low frequency and long
R14
Kilowatt adjust
Relay box (fig.
amplitude, cause could be too much
186)
frequency gain.
Adjust R18.
R15
KVAR admit
Relay box
Counterclockwise adjustment re-
duces the gain; clockwise adjust-
b. Isochronous Operation.
ment increases the gain. If fre-
(1) With the engine not operating, set R1,
quency gain reduction by turning
R11, R14 (on governor control unit), R16
R18 counterclockwise does not stop
and R18 at mid-point by turning full each
this type of hunt, a need for
way and approximately the center. Set
additional feedback gain may be
R16 (on governor control unit) full
indicated. Increase feedback gain
counterclockwise. Set R12 approximately
by turning R16 clockwise. Also if
3/4 counterclockwise.
the reduction of frequency gain
and/or increase of feedback gain
did not stop the slow hunt, an in-
crease in magnetic amplifier bias
level may be indicated; turn R12
more counterclockwise. If none of
these adjustments stabilize the sys-
tem, insufficient capacitance in C8
located in relay box may be indi-
cated. Increase capacitance and
repeat above adjustments.
(d) Load sensing gain R16 not set
properly.
(3) Once set has been stabilized, connect a
d.c. voltmeter (0-10 volt range) across
test points 3 and 4 (4 is positive). Adjust
R1 until frequency is 60 cycles (or 50
cycles) and then adjust R14 until voltage
across test points 3 and 4 is zero volts at
no load.
Figure 135. KFAR adjust and KW adjust.
176
