Figure 4-39.--Standby power supply, door open.

regulated rectifier is controlled with three

MK 19 MOD 3B GYROCOMPASS

silicon-controlled rectifiers. A dc filler is

SYSTEM

incorporated to smooth the output to the

battery .

The Mk 19 Mod 3B gyrocompass system is

identical to the Mk 19 Mod 3A system with the

Two sensing circuits consisting of several

exception of a few changes. The Mk 19 Mod 3B

resistors and a battery charging voltage

system uses a static standby power supply

potentiometer are also included in the charger.

instead of a motor-generator standby supply.

These components automatically sense charging

This standby power supply is considerably more

current and voltage, and send a signal to the

reliable than the motor-generator type since the

battery charging regulator.

only moving parts are the three relays used in

the sensing circuits.

The battery charging regulator receives its

po w e r f r o m a se c o n d w y e - w o u n d se c o n dar y o f

Figure 4-39 is an open-door view of the 3B

the input transformer (a neutral is not used).

standby power supply. The unit supplies a

The output of the transformer is rectified to

highly reliable 3-phase, 400-Hz, 115-volt, line-to-

36 v olts dc. In the battery -charg ing reg ulator,

line power from a 3-phase, 400-Hz, 115-volt or

comparison is made between the sensing

from a 120-volt dc source. For explanation,

circuit output and the second transformer

figure 4-40 is divided into two sections: a battery

se c o n dar y o u tpu t in th e c o n tr o l w in din g s o f

charger and an inverter. The battery charger

the reactor in the regulated rectifier. In this

will be discussed first.

manner, the firing of the silicon-controlled

rectifiers of the regulated rectifier are

The input transformer is a delta-wye, 1 to 1

controlled. By controlling the tiring of the

voltage ratio supplying approximately 110 volts

silicon-control rectifiers, the output of the

ac line-to-line on the secondary and 64 volts ac

regulated rectifier is controlled.

line-to-neutral. The wye secondary is used to

take advantage of the neutral.

A relay is used to delay connection of the

batteries to the charger until rated output is

The input transformer supplies a 3-phase,

obtained.

full-wave rectification circuit. The firing of the

40.125

Figure 4-39.--Standby power supply, door open.

4-37