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 II. Transfer threshold drop-out voltages.

Drop-out Voltage Percentage (%)

Configuration Type (CT)

(Percentage of rated voltage)

CT01

60-70%

CT02

60-70%

CT03

60-70%

CT04

75-85%

CT05

60-70%

CT06

60-70%

CT07

76-80%

CT08

76-80%

CT09

60-70%

CT10

60-70%

3.4.2.3.5 Pick-up voltages. Pick-up voltages for configuration types (see 1.2.3) shall be in accordance with

Table III. A tighter tolerance may be specified (see 6.2) for CT04 and CT05.

TABLE III. Pick-up voltages.

Pick-up Voltage Percentage (%)

Configuration Type (CT)

(Percentage of rated voltage)

CT01

85-95%

CT02

85-95%

CT03

85-95%

CT04

85-95%

CT05

85-95%

CT06

85-95%

CT07

86-90%

CT08

86-90%

CT09

85-95%

3.4.2.3.6 Timing. Unless otherwise specified (see 6.2), timing shall be specified by configuration type (see

1.2.3).

3.4.2.3.7 Instantaneous transfer. On types requiring instantaneous transfer, the time from initiating the transfer

to the closing onto the other source shall not exceed 50 milliseconds.

3.4.2.3.8 Control circuit time delay. Control circuit time delay (CCTD) (see 6.4.5) shall be specified by

configuration type (see 1.2.3).