9905-873

About the 9905-873

Overspeed protection device model 9905-873 is a de-energize-to-trip model. Like other models in the ProTech 203 Overspeed Protection System series, prime mover speed is monitored and calculated by three separate speed-sensing units. These units are all contained in the same key-locked enclosure, which meets NEMA 4 and IP 65 standards.

There are several benefits to using an overspeed protection system with this modular design. The two-out-of-three voting configuration of the three units ensures accurate output even if one of the three units is offline. Because of this, any individual speed sensing unit in the 9905-873 system can be tested or even replaced without having to take the prime mover offline.

The three speed-sensing units in the 9905-873 overspeed protection system are nearly identical. They all are interfaced with their own magnetic pickup (MPU), perform their own speed calculations, have their own operator interface, and have their own power supply. The only difference between the units is that in the 9905-873 model Unit A and Unit B each have a 24 Vdc power supply, while the power supply for Unit C is 220 Vac.

You can find more information on the specifications of model 9905-873 in Woodward ProTech 203 Overspeed Protection System Manual 85191 (version B). This manual should be consulted before installing this system, as it also contains information on location considerations.