9905-996

About the 9905-996

Part 9905-996 overspeed protection device has an energize-to-trip voter relay configuration. During normal operation, the voter relays are in a de-energized state. The locked enclosure of this model is IP 65 certified.

Inside the locked enclosure is a key switch, which is used to access PROGRAM mode for the three speed-sensing units. This prevents unauthorized access to the programming and testing functions of model 9905-996. When the units are in PROGRAM mode, tunable parameters can be set.

ProTech model 9905-996 can be set for a Trip Speed Set Point of 250 rpm to 25,000 rpm and a Magnetic Pickup (MPU) Failed Set Point of 100 rpm to 25,000 rpm. This overspeed protection model has a trip-point frequency range of 250 Hz to 25 kHz. Full product specifications are in Woodward ProTech manual 85196.

If an overspeed condition is detected by one speed-sensing unit, that unit will trip. If an overspeed condition is detected by at least two of the speed-sensing units, a two-out-of-three hardware vote triggers a trip relay to take the prime mover offline. When a trip relay is activated, a code is displayed on the operator interface LCD of the tripped unit(s), an LED indicator is illuminated, and an alarm output is triggered.