Woodward 8440-2176 SPM-D2 Synchronizers

When redundant power supplies are running, current sharing circuitry balances the load to reduce heat

and improve the reliability of the power supplies.

In the event that on supply needs to be replaced, the recommended method for changing

Power Modules is with the power off (to the module being removed and the module being inserted).

The system will tolerate this “cold swap” method without failure.

Each main power supply has four LEDs to indicate power supply health (OK, Input Fault,

Overtemperature, and Power Supply Fault).

See MicroNet Plus Power Supply Troubleshooting (Section 5.5) for a description of the LED indications.

Input power connections are made to the power supply through a plug/header assembly on the front of

the power supply.

The MicroNet Plus Expansion Chassis may use either single or redundant power supplies.

Each power supply module produces three regulated outputs: 

24 V @ 12 A (max), 5 V @ 32 A (max, derated above

55 degree C external ambient temperature), and 5 V Precharge @ 3 A (max).

A motherboard located on the back of the chassis provides the 

interconnection of the three outputs from each power supply module

into three corresponding power busses: 24 V bus, 5 V bus, and 5 V precharge bus.

The 24 V and 5 V busses are load shared between the two power supply modules.

The 5 V precharge bus is not load shared.

Power output regulation at the motherboard, including line, load, and temperature effects,

is less than ±10% for the 24 V bus, +/-5% for the 5 V bus, 

and +/-10% for the 5 V Precharge bus.

The 5 V and 5 V Precharge busses are not for external use.

The 24 V bus is accessible from the motherboard for

external use (protected by 5 A fuses on the source and return lines).