ARMY TM 9-6115-464-34
AIR FORCE TO 35C2-445-2
NAVY NAVFAC P-8-624-34
(b) Convert each of the values obtained in (a) above to a percentage of rated voltage by dividing by
the rated voltage and multiplying by 100. This is the voltage regulation expressed in percent.
(c) Repeat paragraph 4-15d. (1) above substituting frequency for voltage.
(d) Compare the results tabulated in paragraphs 4-15d. (1) and 4-15d. (6) (c) with the requirements of
Table 4-1.
4-15. FREQUENCY ADJUST RANGE TEST
a. General. It is necessary that the frequency of a generator set be adjustable to provide rated frequency at
various load conditions as required in certain applications and to synchronize two or more generator sets for
parallel operation.
b. Apparatus. Instrumentation for measuring load conditions, field voltage and current, and ambient
temperature shall be as described and illustrated in MIL–HDBK-705.
c. Procedure.
(1) Preparation for Test. Connect the load and field instrumentation in accordance with the applicable
figure of MIL–HDBK–705, method 205.1, paragraph 205.1.10.
(2) Test.
(a) Start and operate the generator set and allow it to stabilize at rated load, rated voltage and rated
frequency.
During this period, readings of the load and field instrumentation shall be recorded at minimum
intervals of 10 minutes. If necessary, adjustments to the load, voltage and frequency may be made
to maintain rated load at rated voltage and rated frequency. However, adjustments available to the
operator, specifically adjustments to voltage and frequency adjust devices. Adjustments to the load,
voltage or frequency shall be noted on the stabilization data sheet. Stabilization will be considered
to have occurred when four consecutive voltage and current readings of the exciter field either
remain unchanged or have only minor variations about an equilibrium condition with no evident
continued increase or decrease in value after the last load, voltage or frequency adjustment has
been made.
(b) No further adjustments shall be made to any set control for the remainder of this test except for the
control panel frequency adjust device.
(c) For each of the conditions in the following steps allow approximately 2 minutes between each
adjustment and the subsequent instrument readings.
(d) Adjust the generator set frequency for the specified
record all instrument readings.
(e) Adjust the generator set frequency for the specified
record all instrument readings.
(f) Reduce the load to zero.
maximum frequency at rated load. Read and
minimum frequency at rated load. Read and
(9) Adjust the generator set frequency for the maximum attainable frequency. Read and record all
instrument readings. If the over frequency or overspeed protection device actuates, read and
record all instrument readings just prior to the point of actuation and note on the data sheet that the
protection device actuated.
4-15
