9905-750

About the 9905-750

9905-750 is a de-energize-to-trip overspeed protection device. This model is part of the Woodward ProTech 203 series, which uses MPUs in three identical speed-sensing units to monitor overspeed conditions. Model 9905-750 is the 220 Vac version. Each unit within this system has its own power supply that produces +5 V and +24 V, which is isolated from the input voltage.

Actual unit speed is displayed on the front panels, of which there are three; one for each speed-sensing unit. It is through these panels that each unit is programmed, which can only be done with key lock access to prevent unauthorized programming or testing. This is also where the overspeed test frequency can be adjusted with a potentiometer. All three units are in the same, locked, NEMA 4X certified enclosure.

The 9905-750 system has a multitude of features and available functions, including:

• Remote reset
• Built-in self-test
• Functional status LED indicators (each speed-sensing unit has its own indicators)
• Alarm output
• Key lock to switch between PROGRAM and MONITOR modes
• Hot replacement modular design

The LED indicators will show if an MPU or its wiring has failed, if the corresponding speed-sensing unit has tripped (in which case there is also an alarm output), or if the unit’s CPU is not functioning normally.

The 9905-750 overspeed protection device has a trip speed set point range of 250 rpm to 25,000 rpm, a failed MPU set point range of 100 rpm to 25,000 rpm, and a failed MPU timeout range of 1 second to 533 minutes 20 seconds.

Product Manual 85196 contains more information about the allowable ranges of ProTech 203 model 9905-750, as well as additional product specifications and operation instructions.