TM 9-6115-604-34
NAVFAC P-8-633-34
(h)
Apply the rated load.
(i)
Record all Instrument readings (after transients have subsided).
(j)
Remove the load and adjust the voltage to the maximum attainable just prior to actuation of the
overvoltage protection device.
NOTE
The output voltage may exceed the rating of connected equipment.
(k)
Record all instrument readings (after transients have subsided).
(I)
Apply the rated load.
(m)
Record all instrument readings (after transients have subsided).
(n)
Adjust the voltage to the minimum specified value of 3750 V, line-to-line at the rated load.
(o)
Record all instrument readings (after transients have subsided).
(p)
Remove the load.
(q)
Record all instrument readings (after transients have subsided).
(r)
Adjust the voltage to the minimum attainable just prior to activation of the undervoltage protection device.
(s)
Record all instrument readings (after transients have subsided).
d.
Sample Calculations. Regulation (droop) is defined for the purpose of this method as the no-load value (NLV),
minus the rated load value (RLV), divided by the rated load value expressed in percent regulation:
NLV-RLV
% Regulation =
X 100
RLV
e.
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, 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). The regulation as calculated in step d, above, shall not exceed 2 percent, and the range shall be in
accordance with Table 12-3.
12-23. FREQUENCY AND VOLTAGE REGULATION, STABlLITY, AND TRANSIENT RESPONSE (SHORT TERM).
a.
General. The frequency regulation (droop), or voltage regulation of a generator set is the maximum difference
between the no load value and the value at any load up to and including the rated load. The frequency
difference is expressed as a percentage of the rated frequency of the generator set. The voltage regulation is
expressed as the rms value of the voltage. Stability describes the tendency of the frequency or voltage to
remain at a constant value. Generally, the instantaneous value 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 or voltage is observed. Another term, bandwidth, describes the limits of these variations.
Bandwidth is expressed as a percentage of the rated frequency or voltage of the generator set. Transient
response describes the reaction of the frequency and voltage to a sudden change in some condition, such as the
load change on a generator set. This response consists of the amount of surge 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 or voltage 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 or voltage of the generator set. The recovery time is expressed in seconds.
b.
Apparatus. Instrumentation for measuring load conditions, field voltage and current, and ambient temperature
shall be as illustrated in Figure 12-5. In addition, recording meter(s) for recording voltage and frequency shall be
required.
12-29
