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OM-2031
(b) Generator output monitors (meters)
The generator output is monitored by three instruments; a frequency meter (10) , a voltme-
ter (9) , and an ammeter (7) . The frequency meter is a resonant-reed type, and indicates
the frequency of the generator output alternating current in the range of 380 to 420 Hz
(cycles per second) . The voltmeter indicates the generator output voltage in each phase-
to-neutral (A-N, B-N and C-N) or phase-to-phase (A-B, B-C and C-A) as selected by the
meter selector switch (6) and the line selector switch (5) . (These switches will be de-
scribed below.) The voltmeter has a 3-1/2-inch face and the scale is graduated 0 to 300
V. The ammeter is also 3-1/2-inch size and is graduated 0 to 500 A. The amperage value
in each of the three phases may be read on the ammeter by selecting the desired phase
with switch (6) . Three ammeter current transformers (Ref. 4, Fig. 11) lower the output
load current to a lesser value, of definite ratio, which will operate the ammeter movement
without damage. The ammeter dial scale is graduated and numbered so that the pointer
will indicate the true load current value rather than the meter movement current.
1-1
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Control Box
Figure 6
April 30/96 Revised
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