Figure 6-21.--Crossbar switch.

51.6-volt dc and +5 and +12 volt dc logic voltages. The

switch (fig. 6-21) consists of a welded rectangular

51.6-volt dc is used to trickle charge and equalize

frame that houses 10 vertical (hold) units, 6

charge a 24-cell battery bank. The battery bank is

horizontal select bars, 12 select magnets, and 12

used as an emergency input for the power supply

select off-normal spring pile-ups. Each switch can

when the input from the main IC switchboard fails.

connect 10 sets of three conductors each to any of 30

In the event there is a failure, the power supply

sets of three conductors each. This means one switch

automatically shifts to the battery input. The +5 and

can handle up to 10 connections at any given time.

+12 dc logic voltages are used as inputs to the circuit

All paths are electrically isolated from each other.

card assemblies. Input line filters are also used in the

power supply to prevent line voltage surges from

POWER SUPPLY.-- The switchboard power

affecting the output voltage of the power supply.

supply (fig. 6-22) receives a 115-volt, 60-Hz, single-

Table 6-4 describes the operating controls, indicators,

phase input from the main IC switchboard. The

and indicator-type fuses located on the power supply,

power supply takes this input and internally develops

Figure 6-21.--Crossbar switch.

Figure 6-22.--Power supply.

6-24