TM 5-6115-485-34
T0 3SC2-9-446-2
NAVFAC P-8-625-34
TM 06858B/06859D-34
no load and actuation of the protection devices (if
in MIL-HDBK-7O5, Method 106.1, paragraph 106.
applicable). Compare these results with the require-
1. S and galvanometers having a flat frequency re-
sponse (flat within plus or minus five percent)
ments of table 7-1.
from DC to 3.000 hertz will be required.
7-17. OVERSPEED PROTECTIVE DEVICE TEST.
c.
Procedure.
a. General. To assure that adequate protect-
(1) Preparation for Test.
ion is afforded the generator set against overspeed-
ing, the overspeed protective device must operate
(a) Connect the load and instrumentation
properly.
in accordance with the applicable figure of MIL-
HDBK-705, Method 205.1, paragraph 205.1.10 for
Apparatus. A frequency meter or tachometer
one voltage and frequency.
as described and illustrated in MIL-HDBK-705,
Methods 104.1 or 109.1 shall be required.
(b) Connect the shunt, galvanometers
matching network, oscillograph, and short-circuit-
c . Procedure.
ing switch as illustrated in figure 512.1.1.
(1) Preparation for Test. Connect the fre-
(2) Test.
quency meter in accordance with the l pplicable figure
of MIL-HDBK-705, Method 205.1, Paragraph 205.1.
(a) Start and operate the generator set at
9 or utilize the tachometer in accordance with the
rated voltage, rated frequency and rated load.
manufacturer's instructions. Electronic governor
and throttle stops must be deactivated.
(b) Set the oscillograph time marker to
(2) Test.
a minimum of 0.01 seconds or use a 60 herts timing
trace set the chart speed such that the individual
(a) Start and operate the "generator set at
peaks of the current waveform are clearly visible
rated speed (frequency), rated voltage and no load.
and adjust the peak-to-peak rated current amplitude
to a minimum of 0.5 inch for approximately 12
(b) Slowly increase the engine speed until
millimeters).
the overepeed protective device actuates. Record
the speed of the generator set at this point, and the
(c) Prior to closing the short-circuiting
malfunction indicator light indication.
switch, record a portion of the steady state load for
calibration. With the same load conditions record
all instrument readings.
CAUTION
(d) With oscillograph still recording the.
Do not operate the set in excess of 125
steady state current, close the short-circuiting
percent of rated speed or as otherwise
switch.
limited in the procurement document.
CAUTION
(c) Attempt to start the set. Record if
starting is achieved. If the set did and start, reset
If the circuit interrupter fails to operate
the overspe~ed protective device.
within the specified time, remove the
short circuit to prevent damage. Note
(d) Compare the test results with require-
the failure to operate on the data sheet.
ment of table 7-1.
(e) The generator set contains a short-
7-18. CIRCUIT INTERRUPTER TEST (SHORT
circuit malfunction indicator, check and record its
CIRCUIT).
indication*
a. General. A circuit interrupter is connected
(f) Repeat steps (a) thru (e) above for
between the generator voltage reconnection system
each possible short circuit condition
and the generator set output terminals to disconnect
the generator output from the load and also to protect
the generator from a short circuit. The circuit in-
(g) Repeat steps (a) through (f) above for
terrupter is operated from a current sensor external
both voltage connections if applicable.
to the interrupter.
d. Results.
b. Apparatus. Instrumentation for measuring
load conditions shall be as described and illustrated
(1) From the oscillograms taken in 17-18c
in MIL-HDBK-705. In addition, a non-inductive shunt,
(2)(d), determine the time between the indicated
"short-circuiting switch, galvanometers matching
closure of the short-circuiting switch and the opening
networks, an oscillograph as described and illustrated
of the circuit interrupter. See figure 512. l-IL
7-12
