A. C, Metering and Generator Control
A. C. Ammeter (AM)
Reads the generator load on each phase of the generator. Generator full load rating is 243 amps,
A. C. Voltmeter (VM)
Reads the generator voltage between any two phases. Voltage should read 460 volts at all times
when generator is running. Voltage can be adjusted the volt adjust rheostat located under the
voltmeter switch. Voltmeter can be calibrated for scale by checking the actual voltage at the breaker
with a calibrated voltmeter and adjusting the voltmeter pointer by the screw adjustment on the meter
The Bus voltmeter reads the voltage between phase A & B at all times and is there to compare the
main bus voltage to the generator voltage when paralleling.
Frequency Meter (FM)
Reads the generator frequency. Frequency should always be 60 Hertz at all times when the generator
The bus frequency meter reads the bus frequency at all times and is ther to compare the main bus
frequency to the generator frequency when paralleling.
Ammeter Switch (AS)
Selects which phase of generator load current the Ammeter is reading. The Ammeter is scaled to
read the full generator current at a ratio of 80:1 and a full scale deflection of 5 amps. So at full load of
243 amps the Ammeter will receive 3.04 amps.
The switch shorts out the current transformers that are not connected to the Ammeter which not only
prevents high voltage build up at the open current transformer terminals but also maintains current
sensing for the reverse power relay.
Voltmeter Switch (VS)
Selects two phases of generator to read the voltage on. The voltmeter is scaled to read the generator
voltage at a ratio of 4:1 and a full scale deflection of 150 volts. So at proper voltage of 460 volts the
vlotmeter will recieve 115 volts.
Also selects phase A & B of the bus for proper voltage level comparison before synchronizing.
Voltage Adjust Rheostat
Adjust the generator voltage to maintain 460 volts at all times.