9905-986

About the 9905-986

With the ProTech 203 model 9905-986 overspeed protection device, a trip relay is activated when two speed-sensing units detect overspeed conditions. There are three units in this device that use individual speed calculations and a two-out-of-three voting configuration. If only one unit detects the overspeed condition, that unit trips but the overall system remains online.

This Woodward overspeed protection device monitors prime mover speed with magnetic pickups (MPUs). Speed-sensing units A, B, and C each have their own MPU, as well as their own operator interface and their own 220 Vac power supply.

MPU functional status and overall system operations can be monitored on each unit’s operator interface, which has a two-line LCD and touchpad. Here, tunable parameters such as MPU Failed Set Point and Trip Set Point are programmed. The LCDs will also display error codes, should any unit trip or any problems arise within the 9905-986 system. In the event of a tripped speed-sensing unit, CPU failure, or MPU failure, there are also LED indicators to alert operators of the issue. Some events, such as an activated trip relay, may also be set to trigger an alarm output.

The 9905-986 overspeed protection device is in a locked enclosure, which is certified NEMA 4X when the optional stainless steel hubs are used. This ProTech 203 device samples prime mover speed every 5 ms and has an accuracy rating of 0.05% of point + 2 Hz over the operating temperature range when properly installed and operated.

Woodward ProTech 203 manual 85195 has more product specifications for model 9905-986, including location requirements that should be reviewed before installing this system. Woodward manuals 82715, 82510, and 50532 also contain information relevant to the safe handling of this device.