Woodward 8251-569 UG Actuators

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 overspeed test function is activated when the key switch is in the

PROGRAM position and the operator presses and holds the OVSP TEST button

on the touch pad. The microcontroller switches the source of the MPU signal

from the MPU input to an on-board oscillator. The test speed is annunciated on

the LCD. If the test speed is adjusted above the trip setpoint, using the Test

Frequency potentiometer on each unit, a trip occurs. MPU loss-of-signal

checking is disabled, and the peak speed value does not change during

overspeed test. When the OVSP TEST button is released, the microcontroller

switches the source of the MPU signal back to MPU input and normal operation

is restored. Each ProTech unit must be reset to clear its trip condition.