Adjustment And Test Of Controller And Actuator - Hobart 90 C 20 Operation And Maintenance Manual

OM-2031

(3) Adjustment and Test of Controller and Actuator

Refer to Figure 6. The controller has three identical control potentiometers See inset): the GAIN po-
tentiometer, the DROOP potentiometer, and the potentiometer marked "I". In addition, a SPEED con-
trol potentiometer is located just next to the GAIN potentiometer. Make controller settings as follows:
(a) Preliminary Controller Settings
(1) With the engine of the generator set turned OFF, set the "I" adjustment at the FOURTH in-
crement mark from zero.
(2) Set the GAIN adjustment at the THIRD increment mark from zero.
(3) Set DROOP adjustment COUNTERCLOCKWISE to minimum (zero) position as shown in
Figure 6.
(4) Start the engine and adjust the controller's SPEED potentiometer until engine is operating
at rated speed (2000 RPM) . Turning the adjustment CLOCKWISE increases engine RPM
and turning it COUNTERCLOCKWISE decreases engine RPM.
(b) Checking No-Load Operation of Controller
(1) Turn the GAIN potentiometer control slowly CLOCKWISE until the governor becomes un-
stable and the actuator lever (3,Fig.4) oscillates. (If the actuator lever DOESN'T oscillate at
this setting, upset the lever manually to cause it to oscillate).
(2) Next, turn the same GAIN potentiometer control slowly COUNTERCLOCKWISE until the
governor becomes stable and the oscillations cease.
(3) Turn the "I" potentiometer control slowly CLOCKWISE until the governor again becomes
unstable and the actuator lever (3, Fig. 4) oscillates.
• If the governor DOES NOT become unstable and the lever DOES NOT oscillate, place "I"
potentiometer control setting at approximately EIGHT increment marks from zero (or TWO
increment marks from maximum setting).
• If the governor DOES become unstable, and the actuator lever DOES oscillate, turn the "I"
potentiometer control slowly COUNTERCLOCKWISE until the governor becomes stable
and the oscillations cease.
NOTE: For more accurate and dependable settings, when making GAIN and "I" adjustments, ALWAYS
adjust GAIN before adjusting "I".
(c) Checking Operation of Controller Under Load
Apply a load to the generator set, then remove the load and observe the length of time re-
quired for engine speed to again stabilize. Engine speed should stabilize within 3 to 5 dimin-
ishing oscillations. If this does not happen, proceed as follows:
(1) With the generator set operating at no load, turn the GAIN setting slightly in the COUN-
TERCLOCKWISE direction.
(2) Apply load again to the generator set. Then remove the load again and observe the length
of time required for engine speed to stabilize. It should now stabilize in 3 to 5 diminishing oscil-
lations.
NOTE: If engine speed STILL doesn't stabilize, recheck governor linkage. If linkage is set properly, the
governor controller is probably defective.
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August 5/89 Revised