ARMY TM 9-6115-464-34
AIR FORCE TO 35C2-445-2
NAVY NAVFAC P-8-624-34
4-17. CIRCUIT INTERRUPTER TEST (SHORT CIRCUIT).
a. General. A circuit interrupter is connected between the generator voltage reconnection system 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 interrupter is operated from a current sensor external to the
b. Apparatus. Instrumentation for measuring load conditions shall be as described and illustrated in
MILHDBK-705. In addition, a non-inductive shunt, a short-circuiting switch, galvanometers matching networks,
an oscillograph as described and illustrated in MIL-HDBK705, Method 106.1, paragraph 106.1.3 and
galvanometers having a flat frequency response (flat within plus or minus five percent) from DC to 3,000 hertz
will be required.
(1) Preparation for Test.
(a) Connect the load and instrumentation in accordance with the applicable figure of MIL-HDBK-705,
Method 205.1, paragraph 205.1.10 for one voltage and frequency.
(b) Connect the shunt, galvanometers matching network, oscillograph, and short-circuiting switch as
illustrated in figure 512.1.1.
(a) Start and operate the generator set at rated voltage, rated frequency and rated load.
(b) Set the oscillograph time marker to a minimum of 0.01 seconds or use a 60 hertz timing trace set
the chart speed such that the individual peaks of the current waveform are clearly visible and adjust
the peak-to-peak rated current amplitude to a minimum of 0.5 inch for approximately 12
(c) Prior to closing the short-circuiting switch, record a portion of the steady state load for calibration.
With the same load conditions record all instrument readings.
(d) With oscillograph still recording the steady state current, close the short-circuiting switch.
If the circuit interrupter fails to operate within the specified time, remove the short
circuit to prevent damage. Note the failure to operate on the data sheet. Failure to
observe this caution could result in damage to the equipment.
(e) The generator set contains a short-circuit malfunction indicator, check and record its indication.
(f) Repeat steps (a) thru (e) above for each possible short circuit condition (L1-L0,L2-L3,L1-L2-L3
(g) Repeat steps (a) through (f) above for both voltage connections if applicable.
(1) From the oscillograms taken in 4-18c (2) (d), determine the time between the indicated closure of
the short-circuiting switch and the opening of the circuit interrupter. See figure512. 1.-II.