9905-752

About the 9905-752

This overspeed protection device is part of the Woodward ProTech 203 series. Model 9905-752 is a de-energize-to-trip model with two 24 Vdc input speed-sensing units and one 220 Vac input speed-sensing unit. The three units have separate power supplies, separate front panels, and separate LED functional status indicators, but are all contained in one locked, NEMA 4X certified enclosure.

Aside from the voltage input, the speed-sensing units in the Woodward 9905-752 system are identical. These units act independently to monitor prime mover speed and perform speed calculations. The three units in model 9905-752 are connected in a two-out-of-three voting configuration and activate a trip relay if an overspeed is detected.

If an overspeed is detected and it exceeds the previous peak speed, a new peak speed is recorded and stored in non-volatile memory. A tripped unit will remain tripped until power is cycled or the unit is reset, and all three units must be reset before starting the turbine.

Available features and functions in the 9905-752 device include remote reset, hot replacement, key lock for access to PROGRAM mode, built-in self-test, and an alarm output.

Both the LED indicators and the front panel LCD displays provide information if errors occur. A troubleshooting guide, as well as additional functions and product specs, are detailed in ProTech 203 manual 85196.