Operating Procedure

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,

MAINTENANCE

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-

power stage.

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

high-test voltages.

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

INSTALLATION

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

OPERATING PROCEDURE

protection.

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

potentiometer.

switch, S1, to the OFF position. The standby light, I2,

1-36