AC Voltmeter, Ammeter and Frequency Meter
AC voltage and frequency may be read on the AC voltmeter and frequency meter for
standby power, ground power, generator No. 1, APU generator, generator No. 2 and the
static inverter. Frequency is indicated only when the generator is electrically excited. The
voltage regulator automatically controls the generator output voltage.
Current readings for the two engine IDGs and the APU generator may be read on the AC
ammeter.
The TEST position is used by maintenance and connects the voltage and frequency meter
to the power systems test module for selection of additional reading points.
Normal indications are:
- AC voltmeter – 115 +/- 5volts
- Frequency meter – 400 CPS +/- 10 CPS.
Note: Normal AC voltmeter indication for the APU generator with the AC busses loaded: 110
- 125 volts.
DC Voltmeter and Ammeter
DC voltage and amperage may be read on the DC voltmeter and ammeter for the battery
and each of the three TRs. The standby power and battery bus displays only DC voltage.
Normal indication is 26 +/- 4 volts. During primary charge cycle operation battery voltage
can be as high as 30 +/- 3 volts.
The TEST position is used by maintenance.
