Figure 3-6.--Pictora1 view of ABT-1A2.

selected as the information-sending device to the

alerting watch standers of existing troubles within the

many gyrocompass repeaters of the system. In

systems. The components commonly used with main

addition, each of the individual repeaters in the system

IC switchboards are ABT devices, switches, bus

may be cut in or out of the system without having any

failure alarm units, fuses and fuse holders, lamps and

adverse effect on the operation of the system. The

lamp holders, synchro overload transformers and

switches for the other systems may be used in the same

indicators, and power monitoring instruments,

manner as those for the gyrocompass.

ABT DEVICE.-- The ABT device used with IC

A bank of SR switches is also located on the ACO

switchboards transfers the load from the preferred

section of some switchboards. These switches are used

source of supply if it fails to an alternate source that

to isolate the various speaker groups and alarm contact

remains energized. When the preferred source is

makers of the general announcing system circuit 1MC.

restored, the load is then transferred back to the

preferred source automatically by the ABT device.

ABTs are designed for use in ac or dc, and 60- or

Switchboard Components

400-Hz systems.

ABTs may have either two or three bus transfer

There are several components used with the main

switch positions. Bus transfer switch positions indicate

IC switchboards. The need for these components

the number of power supplies the ABT is designed to

range from providing a means of receiving and

handle. Two-way transfers indicate that the ABT is

distributing power to the various IC systems to

Figure 3-6.--Pictora1 view of ABT-1A2.

3-8