9905-982

About the 9905-982

Woodward ProTech 203 model 9905-982 has three identical speed-sensing units, all enclosed in a single, locked enclosure. If the optional stainless steel hubs are used, this enclosure is NEMA 4X certified. Each of the units comes with its own 120 Vac/dc power supply.

9905-982 is an energized-to-trip model, meaning during normal operation, the voter relays are in the de-energized state. To meet API 612 overspeed trip specifications, a cold-coil monitoring device must be wired into this system.

There are three magnetic pickups (MPUs), each one interfaced with a different speed-sensing unit. Units A, B, and C perform separate speed calculations, then together perform a two-out-of-three hardware vote. If an overspeed condition is detected by one unit, that unit is tripped and operations will continue. If two units detect an overspeed condition, a trip relay is activated in the system, and operations are shut down.

Because model 9905-982 has a modular design and a two-out-of-three voting configuration, several features to reduce system downtime are available. One of these features is hot replacement. If any individual speed-sensing unit needs to be replaced, it can be swapped out without taking the prime mover offline. In this scenario, the two units remaining online will maintain control of the system and continue to provide an accurate output. Similarly, individual units may be tested while the system is online.