% Regulation = NLV - RLV x 100
NLV = No-Load Voltage
RLV = Rated Load Voltage
Results. The data sheets shall indicate the voltage regulation as a percent of rated voltage within the specified
limits at the minimum and maximum specified voltages and the regulation as a percent of rated voltage at the
extremes, the maximum and minimum voltages attainable and the actuation of the protection devices (if
applicable). Compare these results with the requirements of table 16-1.
16-15. FREQUENCY AND VOLTAGE REGULATION, STABILITY AND TRANSIENT RESPONSE TEST (SHORT
General. The frequency regulation (sometimes referred to as droop) of a generator set is the maximum
difference between the no load value of frequency and the value at any load up to and including rated load. This
difference is expressed as a percentage of the rated frequency of the generator set. The voltage regulation is
expressed similarly except that the rms value of voltage is used.
Frequency stability describes the tendency of the frequency to rea3in at a constant value. Generally, the
instantaneous value of frequency is not constant but varies randomly above and below a mean value. Stability
may be described as either short-term or long-term depending upon the length of time that the frequency is
observed. Another term, bandwidth, describes the limits of these variations. Bandwidth is expressed as a
percentage of the rated frequency of the generator set. Voltage stability is described similarly.
Frequency transient response describes the reaction of the frequency to a sudden change in some condition;
such as, a load change on a generator set. This response consists of the amount of excursion beyond the mean
of the new operating band, and the recovery time. The recovery time is the interval beginning at the point where
the frequency leaves the original prescribed operating band and ending at the point where it enters and remains
within the new prescribed operating band. The amount of surge is expressed as a percentage of the rated
frequency of the generator set. The recovery time is expressed in seconds. The voltage transient response is
Apparatus. Instrumentation for measuring load conditions, field voltage and current, and ambient temperature
shall be as described and illustrated in MIL-HDBK-705. In addition, recording meter(s) for recording voltage and
frequency shall be required. The recording meters shall be as described in table 2-1.
Preparation for test.
Connect the load and field instrumentation in accordance with the applicable figure of MIL-HDBK-
705, Method 205.1, paragraphs 205.1.10, for one voltage and frequency. Connect the signal input of
the recording meter(s) to the convenience receptacle of the set or to the generator coil which is used
as the voltage sensing input to the voltage regulator. (Power the recording meter(s) from the
Set the recording meter charge speed(s) to a minimum of 6 inches per hours. The following items
shall be recorded on both the data sheets and recording chart(s):