should light. Turn the drive switch, S1, to the START
Turning the drive switch to the START position
position. The power on light, I1, should light, and the
removes the 30-volt dc signal from the binary circuit and
standby light, I2, should go out. After the output of the
allows the first negative-going edge of the 800-Hz
inverter has reached a steady state (approximately 2
square wave (waveform B) to reverse the bistable multi-
seconds), turn the drive switch, S1, to the RUN position.
vibrator in the SYNC stage. This allows the positive-
Adjust the voltage, and adjust potentiometers R785,
going edge of waveform B (at time 0, fig. 1-40, view A)
R786, and R787 to the required output for each phase.
to trigger the monostable multivibrator in the main
Use the voltage selector switch, S2, and meter, M1, to
VPWG (fig. 1-38).
read the voltage of each phase.
The trailing edge of the first positive half of
The output voltages must be adjusted in the follow-
waveform C (edge No. 1, fig. 1-40, view A) from the
ing sequence: phase CA, phase AB, and then phase BC.
main VPWG triggers the main 40-Hz countdown
circuit. The main 400-Hz countdown output (D) triggers
To secure the inverter, turn the drive switch, S1, to
the pulse generator in the driver that generates the pulse
the OFF position, and then turn the power circuit breaker
(E) to trigger the power SCRs for one side of the power
CB1 to OFF.
stage. The main 400-Hz countdown (D) and the leading
edge of the second positive half of waveform C (2,
fig. 1-40, view A) provide coincident gating for the
pulse generator in the driver that generates the pulse (F)
Maintenance of the static inverter should normally
to trigger the commutating SCRs in this side of the
be limited to simple replacement with a new or service-
able module. This will ensure rapid restoration of the
The main 400-Hz countdown output(G) triggers the
inverter into service without risking dangers of handling
pulse generator in the driver that generates the pulse (H)
to trigger the power SCRs in the other half of the power
Complete familiarization with the theory of opera-
stage. Waveform G and the leading edge of the next
tion must be obtained before troubleshooting is
positive half of waveform C (3, fig. 1-40, view A) gate
attempted. Then follow the step-by-step procedures out-
the pulse generator in the drive that generates the pulse
lined in the manufacturer's technical manual while
(J) to trigger the commutating SCRs in this half of the
using the specified test equipment.
power stage. The leading edge of waveform C controls
the duration of the ON time of the power stage.
RECTIFIER POWER SUPPLY
The leading edge of the 180° signal (K) from the
main VPWG triggers the phase control VPWG. The
The rectifier power supply is a regulated dc power
phase control VPWG provides a delay in time (N)
supply. It is intended to furnish 120-volt dc power for
between the main and secondary VPWGs to control the
interior communication and fire control application. Its
phase angle between the two power stages.
input is 440-volts ±5 percent, 60 cycles ±5i percent,
3-phase. It will produce a dc output adjustable from
The secondary VPWG is triggered by the trailing
below 117 volts to above 126 volts at a load of 1 kW.
edge of the phase control VPWG signal (waveform N,
The output voltage is regulated within 5 percent against
fig. 140, view B). The trailing edge of waveform P from
the combined effects of load and line fluctuations,
the secondary VPWG triggers the secondary 400-Hz
countdown. The outputs from the secondary 400-Hz
countdown (U and R) and the leading edge of the
secondary VPWG output (P) trigger the pulse
The equipment is bulkhead mounted in a drip-proof
generators in the secondary driver in the same manner
cabinet. No switches, meters, or external controls are
as just described for the main driver. The sequence of
provided. Two phase rotation lights are on the front of
operation for the secondary power stage is the same as
the cabinet. One light is for correct phase rotation of
for the main power stage.
input 3-phase power and the other is for incorrect phase
rotation. Fast-acting fuses are provided for circuit
Voltage checks are made at the load if incorrect
To operate the static inverter, turn the main power
adjustments are made internally by repositioning a
circuit breaker CB1 (fig. 1-37) to ON. Turn the drive
switch, S1, to the OFF position. The standby light, I2,