ARMY TM 9-6115-643-24
AIR FORCE TO 35C2-3-445-22
m. Examine voltage and frequency recorder chart. Generator set should meet the following performance criteria:
(1) Frequency regulation shall not exceed 1/4 of 1 percent of rated frequency.
(2) Frequency short-term stability (30 seconds), frequency will remain constant within a band width equal to 1/2
of 1 percent rated frequency, without repetitive frequency variations, commonly called hunting.
(3) The generator set will reestablish stable engine operating conditions within 2 seconds of a sudden load change
(within 1 second for 400 Hz unit). The maximum transient frequency change above or below (overshoot or
undershoot) the new steady state frequency shall not be more than 4 percent of rated frequency (not more
than 1-1/2 percent for 400 Hz unit).
If the above criteria is not met, adjust the governor control unit (3, FIGURE 4-1) in accordance with paragraph
If the above criteria cannot be met by adjustment, the governor control unit must be replaced.
Disconnect load bank and close load terminal board access door.
Disconnect voltage and frequency recorder, install voltage reconnection terminal board protective cover and close
output box access door.
Shut down generator set.
Open output box access door, remove cover from voltage reconnection terminal board and attach voltage and
frequency recorder to terminals 9 and 12 of voltage reconnection terminal board.
N O T E
The following procedures require monitoring frequency, voltage, cur-
rent, and power. All readings except for frequencies will utilize the gen-
erator set control panel gages. However, since the designed overspeed
trip frequency is greater than the range of the control panel FREQUEN-
CY meter (HERTZ), a frequency counter will be required.
Attach frequency counter to voltage reconnection terminal board terminals 9 and 12.
Open load terminal board access door and attach load bank to generator set (four wire connection).
Ensure load bank and generator set voltage reconnection are set for
same configuration (i.e., 120/208 or 240/416 VAC).
Check for proper adjustment of governor actuator, paragraph 4.14.3. Adjust as necessary.
Check for proper adjustment of magnetic pickup, paragraph 2.108.4. Adjust as necessary.
Lower generator set control panel and turn INTEG, GOV GAIN, and LOAD PULSE potentiometer on governor
control unit to their full counterclockwise positions.
Start generator set and operate at rated voltage and frequency.
Observing frequency counter, slowly increase operating frequency of generator set by turning governor control
unit FREQ range potentiometer clockwise until frequency counter indicates between 65.94 and 66.06 Hz
(MEP-804A) or between 436 and 444Hz(MEP814A). At this point generator set has reached overspeed trip fre-
quency and generator set should shut down.
Perform steps j and k if generator set does not shut down within limits
noted in step i. Otherwise, proceed to step 1.