About the 9905-880
This overspeed protection system is part of Woodward’s ProTech 203 series. It is a 220 Vac version (one power supply per speed sensing unit) and is one of several de-energize-to-trip versions available. The components of model 9905-880 are in a single enclosure that, if the optional stainless steel hubs are used, meets NEMA 4X standards.
Model 9905-880 has a 100 Hz to 32 kHz speed-sensing frequency range. Speed is sampled every 5ms by magnetic pickups (MPUs) interfaced with each ProTech 203 9905-880 speed sensing unit. The overall system has a 40 ms max total response time. The trip-point frequency range of this system is 250 Hz to 25 kHz.
A trip relay is activated when overspeed conditions are met. If conditions are met by only one of the three units, only that unit is tripped and the rest of the system remains online.
Features of the model 9905-880 include:
- MPU failure indicator
- CPU failure indicator
- Hot replacement
- Remote reset
- Alarm outputs
Additional features and 9905-880 specifications can be found in Manual 85191 (version B).
Model 9905-880 should be kept in MONITOR mode during normal operations, though it will run either MONITOR mode or PROGRAM mode. Access to the switch between the two modes is restricted through a key switch on the enclosure.