scope:

This specification covers alternating current (a.c.) and direct current (d.c.) electric power bus transfer switches for Naval shipboard use. Semiconductor (solid-state) devices used for transfer switch control circuits are included. Solid-state transfer switches are not included.

Bus transfer switches shall be classified by standard part numbers as specified in 1.2.1 through 1.2.1.6 (see 6.2.1).

The standard part numbers for the bus transfer switches shall be designated as follows: Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: Commander, Naval Sea Systems Command, SEA 55Z3, Department of the Navy, Washington, DC 20362, by using the self-addressed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter.

ABT - denotes automatic bus transfer switch.

MBT - denotes manual bus transfer switch.

1 - 120 Volt (V) a.c. 115 Vd.c.

2 - 208 Va.c. 230 Vd.c.

4 - 450 Va.c.

A - denotes 60 hertz (Hz) application.

D - denotes d.c. application.

F - denotes 400 Hz application.

1 - denotes transfer switch has control circuit time delay and is instantaneous and selective.

2 - denotes transfer switch has control circuit time delay and full phase protection and is instantaneous and selective.

3 - denotes transfer switch has control circuit time delay and line circuit delay or inphase monitor and is selective.

4 - denotes transfer switch is instantaneous and non selective.

5 - denotes transfer switch has control circuit time delay on voltage sensing, instantaneous drop-out on frequency sensing, instantaneous drop-out below 60 to 70 percent voltage and contains an inphase monitor.

6 - Same as 3 except transfer switch is non-selective and d.c. has no line circuit time delay.

9 - Same as 3 except 3-way transfer switch with selective transfer between normal and alternate, and non selective to emergency. D.c has no line circuit time delay.

Note: Unless otherwise specifically specified (see 3.5.2.10.8), full phase protection may be incorporated in automatic bus transfer switches.

"S" shall be added after the last significant designation of application to show special features, such as: a non standard pick-up and drop-out voltage setting, frequency sensitive, load fuses, and special timing. For item identification, substitute an sbstract letter.

XXX - denotes current rating of bus transfer switch in amperes (A) (see 3.4.4 and table I).

intended Use: