Hobart Brothers 6910, Operation And Maintenance Manual With Illustrated Parts List

Page: 86 / 206

(3) Adjustment and Test of Controller and Actuator (Series 6910, 6910A, and
6910B Generator Sets)
Refer to Figure 6. The controller has three identical control potentiometers (see inset): the GAIN
potentiometer, the DROOP potentiometer, and the potentiometer marked “I”. In addition, a
SPEED control potentiometer is located just next to the GAIN potentiometer. Make controller set-
tings as follows:
(a) Preliminary Controller Settings
•
With the engine of the generator set turned OFF, set the “I” adjustment at the FOURTH in-
crement mark from zero.
•
Set the GAIN adjustment at the THIRD increment mark from from zero.
•
Set DROOP adjustment COUNTERCLOCKWISE to minimum (zero) position as shown in
Figure 6.
•
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
•
Turn the GAIN potentiometer control slowly CLOCKWISE until the governor becomes un-
stable and the actuator lever oscillates.
(If the actuator lever DOESN’T oscillate at this set-
ting, upset the lever manually to cause it to oscillate) .
•
Next, turn the same GAIN potentiometer control slowly COUNTERCLOCKWISE until the
governor becomes stable and the oscillations cease.
•
Turn the “I” potentiometer control showly CLOCKWISE until the governor agains becomes
unstable and the actuator lever
(3, Fig. 1 ) oscillates.
•
If the governor DOES NOT become unstable and the lever DOES NOT oscillate, place the
“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.
•
Upset the actuator lever by hand. If the lever oscillates in 3 to 5 diminishing oscillations
and stops, the setting is correct.
NOTE : For more accurate and dependable settings, when making GAIN and “I” adjustments, ALWAYS
adjust GAIN before adjusting “I”.
(3) 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:
•
With the generator set operating at no load, turn the GAIN setting slightly in the COUN-
TERCLOCKWISE direction.
•
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
oscillations.
NOTE
: If engine speed STILL doesn’t stabilize, recheck governor linkage. If linkage is set properly,
the governor controller is probably defective.
2-3 May 1/91 Revised
Page 14
OM-2028