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Radar System Engineering

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574 PRIME POWER SUPPLIES FOR RADAR [SEC. 146<br />

to + 10”C shall be 390 to 410 cps; over the same range of voltage and<br />

load, the frequency limits for a temperature range of – 55°C to +70”C<br />

shall be 380 to 420 cps.<br />

Table 14.5 gives the frequency range of inverters now in general use,<br />

and in the column headed “ Remarks” the motor type or method of<br />

speed control is indicated. All data refer to a temperature of 25°C and<br />

sea-level pressure.<br />

TARLE14,5.—SPEEDCONTROL OF CERT.AIN MOI-OR-ALTERNATOII SETS<br />

h’manufacturer<br />

Rating<br />

va phase:<br />

St]-le<br />

Frequency, cps<br />

26 volts 29 volts<br />

full load + load<br />

Remarks<br />

Eclipse . . . . . . . . . . . . . . 100 3+<br />

Eclipse . . . . . . . . . . . . . 250 3+<br />

Leland. . . . . . . . . . . . . . . .500 10<br />

Wincharger 750 1+<br />

Holtzer-C’abet, 1000 3+<br />

Leland . . . . . . . . . . . . . . . 1500 1+<br />

GE . . . . 1500 1$+<br />

Air!vays . . . . . 2500 ld<br />

Eclipse* . . . . 840 1+<br />

]~123_l-A 410 410<br />

1?121-1-.4 MO 410<br />

10596 395 475<br />

PU-16 390 403<br />

MG- 153 340 395<br />

PI?-21S-C 395 450<br />

PB21S-D 395 440<br />

IT-7 410 430<br />

800-1-C 730 900<br />

Lee Regulator<br />

Lee Regulator<br />

Compound-wound<br />

Carbon-pile regulator<br />

Resonant<br />

Shunt-wound<br />

Shunt-wound<br />

Regulating field<br />

Compound-wound<br />

● Nominal rated frequency 800 CDS.<br />

Lee Reaulator.—The Lee speed regulator is a centrifugal device which<br />

alternately opens and closes a short circuit across a fixed resistor in<br />

series with the motor field. The short-circuiting contacts are on the<br />

centrifugal device and can be set to open and close at any predetermined<br />

speeds within 5 per cent of each other. Speed regulation is therefore<br />

good; it can be maintained at approximately 5 per cent. This type of<br />

regulator creates a good deal of r-f noise that is difficult to suppress, and<br />

gives pronounced modulation of the output voltage.<br />

Voltage Regulator Control. —Speed regulation can also be provided<br />

by means of a regulating field controlled by the generator voltage regulator.<br />

This method is used in the 2500-va Type PU-7 inverter designed<br />

by Wincharger and built by Wincharger and Airways. It is shown<br />

schematically in Fig 14.18.<br />

As the input voltage or inverter load changes, the resistance of the<br />

carbon pile in the voltage regulator varies to maintain constant output<br />

voltage. This also serves to vary the current through the motor regulator<br />

field in the proper sense to maintain constant speed. The motor is<br />

designed to obtain proper division of flux between the main field and<br />

the regulating field. The resistances of the regulating field and of the

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