Product Description

Woodward’s ProTech 203 model 9905-878 is designed for reliable overspeed protection. This two-out-of-three hardware vote device permits normal operations with an accurate output provided two of the three speed-sensing units are online, which permits hot replacement, testing of individual units while the prime mover is online, and continuing operations in the event one of the units is tripped. An inadvertent turbine trip will not occur from a single MPU failure.

Each of the three speed-sensing units within model 9905-878 has a 24 Vdc power supply (18–32 Vdc, 7.25 W voltage range). Each one produces +5 V and +24 V, which is isolated from the input voltage. All three units are in the same enclosure. The locked enclosure of this ProTech 203 model is NEMA 4X certified as long as it uses the optional stainless steel hubs.

This is a de-energize-to-trip model. It has LED indicators on each unit to alert operators of a tripped unit, an MPU failure, or a CPU failure. There is also an alarm output to notify of a tripped unit.

A tripped unit must be reset (or the power cycled) before being brought back online, and each unit must be reset before starting the turbine. The 9905-878 overspeed protection system includes a convenient remote reset feature.

The installation and operation manual for models 9905-878 is Woodward’s ProTech 203 Overspeed Protection System Manual 85191 (version B). In this manual, you can find additional product specifications, installation location requirements, programming instructions, and more.