(c) Open the switch and adjust the resis-
tance, R2 until Voltmeter Number 2 reads the under-
voltage value specified in Table 16-1. This test shall
be repeated for each undervoltage value.
(1) Preparation for test. With the set not oper-
ating remove the protective device tap from the en-
gine-block and reconnect as shown in figure 515. 1-I
with the protective device and oil pressure gage in
approximately the same horizontal plane as the pro-
tective device tap located on the engine.
(d) Repeat steps (b) and (c) above to assure
that the specified undervoltage and rated voltage set-
tings are correct.
(e) Set the oscillograph chart speed such
that the individual waveform peaks are clearly visible.
Set the timing lines to a minimum of 0. 01 seconds per
line or usc a 60 Hertz timing trace. With the switch
open, adjust the trace peak-to-peak amplitude to a
minimum of one inch (or 25 millimeters).
(a) With the bleeder valve closed and the
shut-off valve in the oil pressure line open, start and
operate the set at rated speed (use the set instrumen-
tation) and at no load.
(f) With the set operating and the circuit
interrupter and the switch open, read and record
both voltmeter readings.
(b) Open the bleeder valve slightly to purge
air from the system.
(c) Close the bleeder valve and record the
oil pressure as indicated on the external gage.
(g) Close the switch and circuit interrupter,
(h) With the oscillograph recording, open
(d) Almost completely close the shut-off
v a l v e .
(i) After allowing sufficient time for the
circuit interrupter to operate, check and record the
indication of the undervoltage malfunction indicator.
(e) Slowly open the bleeder valve until the
low oil pressure protective device shuts down the
Record the reading of the oil pressure gage
at the point of set shutdown (see figure 515. l-II).
(j) Close the switch, and close the circuit
(f) Record operation of the malfunction in-
(k) Repeat steps (e) thru (j) above two ad-
d . Results. Compare the value of shutdown pres-
sure with the requirement of Table 16-1.
(l) Repeat (a) thru (k) for the other under-
voltage value specified in para. 16-1.
16-22. Overtemperature Protective Device Test.
a. General. The overtemperature device must
be capable protecting the engine in the set against
overheating for any reason.
(1) From the oscillograms made in 16-20c
determine and tabulate the time between the appli-
cation of the overvoltage and operation of the circuit
interrupter for each application of overvoltage.
Instrumentation for measuring load
conditions and set and ambient temperatures shall be
as described and illustrated in MIL-HDBK-705,
Method 205.1, Paragraph 205.1.10.
(2) From the oscillograms made in 16-20d
determine and tabulate the time between the application
of the undervoltage and the operation of the circuit
interrupter for each application of undervoltage.
(1) Preparation for test.
(3) Compare these results with the require-
ments of table 16-1.
(a) Connect the load instrumentation in ac-
cordance with the applicable figure of MIL-HDBK-705,
Method 205.1, Paragraph 205.1.10.
16-21. Low Oil Pressure Protective Device Test.
a. General. Since generator sets frequently oper-
ateunattended for long periods, the engine is
equipped with a low oil pressure protective device.
This device shuts down the engine when the oil pres-
sure drops below the safe limit.
(b) Install a thermocouple to measure the
same temperature as seen by the protective device
The following equipment shall be
required to perform this test.
(a) Start and operate the generator set at
rated voltage, rated frequency (speed), and rated load.
Oil pressure gage (± 1%)
Flexible oil line (or copper tubing)
(b) Block the cooling air to the generator set
by any suitable means.