generator frequency (speed) and the voltage of each L-L and L-N condition. With the generator operating
at rated voltage, frequency, and no load, the maximum difference in the three line-to-neutral voltages shall
be not more than 1 percent of rated line-to-neutral voltage. The maximum difference between the voltages
of the 120-volt windings of any one phase shall be not more than one volt.
Generator with separate excitation.
Determine from the data obtained in 16-13d(2) the maximum and minimum L-L and L-N voltages.
The voltage unbalance is the difference between the maximum and minimum L-L voltages. To express
this in percent, divide this difference by rated L-L and multiply by 100.
Voltage Unbalance (Coil) in percent = V max - V min X 100
Compare the results of step (2) above with the requirements.
16-14. REGULATOR RANGE TEST.
General. The voltage adjust device associated with the voltage regulator provided with the generator set must
have adjustment capable of varying the regulated voltage throughout the limits and under the various load
conditions and temperature ranges without causing the voltage droop of the set to exceed specification limits.
The voltage adjust device also must be capable in some cases of providing and operating voltage other than
rated voltage for special types of equipment and to compensate the external line drop.
Apparatus. Instrumentation for measuring load conditions, ambient temperature, and the generator field (or
exciter field) voltage and current shall be as described in MIL-HDBK-705.
Preparation for Test.
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 for one voltage and frequency.
Start and operate the generator set and allow the set to stabilize at rated load, rated voltage and
rated frequency. During this period record all instrument readings including thermal instrumention at
minimum intervals of 10 minutes. If necessary, adjustments of the load, voltage and frequency may
be made to maintain rated load at rated voltage and frequency. Adjustments to the voltage and
frequency shall be limited to those adjustments available to the operator, specifically adjustments to
the voltage or frequency adjust advices. On sets utilizing a droop-type speed control system as the
prime speed control, the speed and droop portions of the control may be adjusted. No other
adjustments to the voltage and frequency control systems shall be made. Adjustments to load,
voltage or frequency controls shall be recorded on the data sheet at the time of adjustment.
Stabilization shall be considered to have occurred when four consecutive voltage and current