9905-876

About the 9905-876

The ProTech 203 Overspeed Protection System series by Woodward has many available versions. Model 9905-876 is an energize-to-trip version, with a 120 Vac/dc power supply (voltage range of 88–132 Vac/90–150 Vdc, 7.25 W) for each of the three speed-sensing in the system.

Model 9905-876 works by performing three separate speed calculations based on the readings of three separate magnetic pickups (MPUs), which continually monitor prime mover speed. A trip relay is activated when a two-out-of-three hardware vote detects an overspeed condition. An individual speed-sensing unit may trip from an overspeed condition, loss of MPU signal, or other conditions outside of normal operating parameters. Details are in ProTech 203 Manual 85191 (version B).

The design of model 9905-876 avoids unnecessary system downtime by allowing the prime mover to remain online with two of the three units maintaining accurate output, so if a single unit trips, is being tested, or needs to be replaced, the overall system will remain operational.

Additional features of model 9905-876 include:

• Remote reset
• LED functional status indicator for MPU failure, tripped unit, CPU errors, etc.
• Alarm output
• Key locked enclosure (NEMA 4, IP 65 standards)

 The LED indicators, a separate set for each speed-sensing unit, are located on the front of that unit’s operator interface. There is also an LCD and touchpad on each interface.