d.
Rotate the engine as required to locate a ring gear tooth directly below the tapped, pickup
mounting hole. Continue turning pick-up CLOCKWISE until it bottoms out (hits a ring gear
tooth).
e.
Back the magnetic pick-up outward 1/4 to 3/4 of a turn COUNTERCLOCKWISE. This creates
a gap between the magnetic pick-up and the ring gear.
f.
Re-connect pick-up wires to terminals 10 and 11 of the governor controller.
g.
Start the engine and run it at idle speed.
h.
Check voltage at terminals 10 and 11. The signal should read about 10 V-AC.
i.
If the signal is weaker than 4-V AC, check connections. If necessary, check magnetic pick-up
continuity with an ohmmeter.
j.
Tighten the jam nut when the pick-up is properly adjusted.
NOTE: A minimum of 2.5-V AC is required during engine cranking. This minimum voltage is necessary
to energize the electronics of the control box. At rated speed, the magnetic pick-up voltage could go
as high as 25-30-V AC without damage to the internal electronics of the control box.
(3)
Governor control box adjustment (See fig. 5)
The control box has three control potentiometers (pot) for setting the response characteristics of
the governor system. They are: “I”, “D”, and “GAIN.” There is a forth potentiometer named
“DROOP”, which is not used in this installation. It is set to zero of minimum. There are two
potentiometers for controlling speed. The “SPEED” potentiometer in the control box is for setting
IDLE speed. The potentiometer on the external printed circuit board is for setting the RATED
speed. These are both multi-turn controls. They are also interactive with each other.
Make the controller settings as follows:
a.
Preliminary controller settings
Turn the engine OFF
•
Set the “I” potentiometer (pot) (2) to the FORTH increment mark from zero.
•
Set the “D” potentiometer (3) to the THIRD increment mark from 0 (zero).
•
Set the “GAIN” potentiometer (4) to the THIRD increment mark from 0 (zero).
Magnetic Pick-Up Adjustment
Figure 4
OM-2084 / Operation and Maintenance Manual
90CU24 / Series 500392 Generator Sets
Chapter 2-3
November 27/1997
Page 14
