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MIL-PRF-17773 Switches, Bus Transfer, Electric Power Automatic And ManualThis specification covers the Automatic Bus Transfer Switch \(ABT\) \(see 6.4.1\) and the Manual Bus Transfer Switch \(MBT\) \(see 6.4.13\), herein referred to as ABT, MBT, or switch\(es\), for use on surface and submarine Naval vessels. Unless otherwise specified herein, this specification applies to both ABTs and MBTs. Requirements for Static or Solid State ABTs \(SABTs\) are not defined in this specification. MIL-PRF-32150 specifies requirements for SABTs.

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MIL-PRF-17773C(SH)

TABLE IX. Classification of defects. Continued.

Related Requirements

Categories

Defects

Paragraph

007

Single or full phase protection not provided as specified.

3.4.2.3.12

008

Indicator lights not specified colors.

3.4.5.1

009

Test switch not provided for ABT switches.

3.4.5.2.4

010

Fusing of control circuits and indicator circuits not as specified.

3.4.6

Manual operator does not have a mechanical position indicator for

011

3.4.7

supply line indication.

012

Transfer positions are not two-way as specified.

3.4.34

013

Number of line phases not as specified for switches.

3.4.36

101

Parts not in conformance with applicable specifications.

3.2.3 and 3.5.8

102

Light emitting diodes not as specified.

3.2.4

103

Relays not as specified.

3.2.7

104

Information plates, identification plates, and marking not as specified.

3.2.9

105

Cable entrances not as specified.

3.2.11

106

Wire, wiring methods, and marking not as specified.

3.2.12

107

Diagrams and descriptions of operation not provided as specified.

3.2.14

108

Auxiliary switches not as specified.

3.4.10

Terminal boards not provided or wire connection points not accessible

3.4.13

109

and identifiable.

110

Degree of enclosure not as specified.

3.4.41

201

Creepage and clearance distances not as specified.

3.2.8

202

Painting not as specified.

3.2.17

4.6 Methods of inspection.

4.6.1 Operational tests.

4.6.1.1 Order of precedence. The following tests shall be completed in the following order and a successful

completion is required to continue:

Shock (see 4.6.25)

Vibration (see 4.6.26)

Short circuit withstandability (see 4.6.17)

Dielectric withstandability (see 4.6.18)

4.6.1.2 Automatic operation. ABTs shall be operated to determine that the operating voltages are as specified

in 3.4.2.3.3. Not less than five transfers and five re-transfers shall be made under conditions of constant

temperature, frequency, and rate of change of voltage. Testing shall also be performed using asynchronous sources

at worse case scenario of 180 degrees out of phase.

4.6.1.3 Manual operation. When manual mode has been selected (see 3.4.2.), automatic control circuit devices

shall not be operable while the manual-automatic selector switch is in the manual position; the ABTs shall not

automatically transfer.