9907-151

About the 9907-151

Part 9907-151 is a 220 Vac overspeed protection device in the ProTech 203 series by Woodward. This is a de-energized-to-trip model that detects overspeed conditions by using magnetic pickups (MPUs) to monitor prime mover speed. If overspeed conditions are detected and confirmed by speed-sensing units by way of a two-out-of-three hardware vote, a trip relay is activated.

ProTech model 9907-151 has both visual and audible alarms to indicate a trip. These include LED indicators, an alarm output, and an error code on the unit’s LCD display. Possible causes of a trip include:

• Present Speed of a unit exceeds the Trip Set Point value
• Internal hardware problem
• An overspeed test brought the Present Speed above the Trip Set Point
• MPU failure, such as a sudden loss of speed
• Disconnected internal cable
• Loss of MPU signal
• MPU Fail Timeout

Parameters such as Trip Set Point and MPU Fail Timeout can be set when the units are in PROGRAM mode, which can only be accessed by using a single key switch connected to all three speed-sensing units. The enclosure of model 9907-151 meets NEMA 4 and 4X standards for North America, and IP54 for Europe.

Each time a unit trips it must be reset before being brought back online (or the power must be cycled. Units must also be reset before the turbine is started. ProTech model 9907-151 permits resetting units from a remote location through the system’s remote reset feature.