The meters specified herein are for military unique applications requiring ruggedized design and allow proper performance under extreme military operating conditions, which include vibration, thermal shock (65°c to +85°c), mechanical shock (100 G's), and high humidity and temperature. In addition, these military requirements are verified under a qualification system. Commercial components are not designed to withstand these military environments.

Two designs of alternating current voltmeters are covered under this specification (see 3.1). Voltmeters, both of the moving iron-vane types and the rectifier types, are included. They are not electrically interchangeable, as noted below:

a. Moving iron-vane types:

1. Are sufficiently accurate for various wave forms (for crest factor to 2.3, see 6.5.3).

2. Are limited to application to frequencies for which they are designed.

3. Power consumption is significantly greater than rectifier types.

b. Rectifier types:

1. Are inherently inaccurate for non-sinusoidal waves.

2. Frequencies effective between 50 Hz and 1,000 Hz.

3. Power consumption is considerably less than moving iron-vane types.