Figure 3-19.--Static inverter.

The meter panel assembly contains the instru-

STATIC INVERTER

ments and controls necessary for the opration of the

The need for a highly dependable, static, 400-Hz

equipment.

power supply led to the development of the 4345A

The inverter module assembly contains a control

static inverter.

circuit +30-volt dc power supply, a drive circuit

+30-volt dc power supply, an input sensing circuit, a

The model 4345A static inverter delivers a closely

synchronizing subassembly, two variable pulse width

regulated 400-Hz, 3-phase, 120-volt output from a

generators, a frequency standard oscillator, a

250-volt dc source. Two single-phase static inverters

phase variable pulse width generator, two drive sub-

are operated with a controlled 90-degree phase

assemblies, a step change adjustment circuit, and two

difference. Pulse width modulation is used for control

silicon control rectifier power stages.

of the output voltage of each static inverter. The

The power stage assembly contains capacitors,

outputs of the two inverters are fed into two Scott

transformers, and filters associated with the power stage

of the inverters.

"T''-connected transformers to provide a 3-phase

output from a 2-phase input.

Maintenance

The 4345A static inverter is enclosed in an

aluminum cabinet (fig. 3-19), divided into three

Maintenance of the static inverter should normally

be limited to simple replacement with a new or service-

sections. These are the meter panel assembly, the

able module. This will ensure rapid restoration of

inverter module assembly, and the power stage

the inverter into service without risking dangers of

assembly. A resistor subassembly is located on the

handling high-test voltages,

back of the cabinet.

Complete familiarization with the theory of

operation must be obtained before troubleshooting is

attempted. Then follow the step-by-step procedures

outlined in the manufacturer's technical manual while

using the specified test equipment.

SUMMARY

In this chapter, we have discussed the ship's

service, emergency, and casualty PO wer distribution

systems found on board Navy ships and their impor-

tance in supplying power to the IC switchboards and

various IC systems.

We have discussed the main and local IC switch-

boards used to supply power to IC systems, the compo-

nents associated with the switchboards, and

switchboard maintenance. We have identified IC

systems by their classification and described a typical

IC test switchboard installed in IC shops for bench

testing IC equipment.

Now that you have finished this chapter, you should

have a better understanding of motor and generator

repair and troubleshooting.

The information covered in this chapter does

not include the necessary specifications or the specific

procedures for repair and maintenance of each piece of

equipment you will encounter. This information can

only be obtained from the appropriate NSTM and the

manufacturers' technical manuals.

Figure 3-19.--Static inverter.

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