9905-983

About the 9905-983

This Woodward ProTech 203 model uses three magnetic pickups (MPUs), each interfaced with a separate speed-sensing unit. The three units, A, B, and C, have individual power supplies (220 Vac), operator interfaces, and error notification LEDs and alarm outputs.

As an energize-to-trip model, voter relays are in the de-energized state until an overspeed condition is detected. Voter relays change state, and a trip relay is activated if two of the three speed-sensing units detect an overspeed condition. If only one unit detects the condition, that individual will trip while the other two remain in normal operation.

There are options for stainless steel hubs for this overspeed device. When these are used, the 9905-983 enclosure meets NEMA 4X certification standards. This system meets API 612 overspeed trip specifications only if a cold-coil monitoring device is wired into the 9905-983.

Units A, B, and C are programmed separately but must be programmed with identical set points for the system to function properly and safely. The key switch to put the units in PROGRAM mode is accessed only by unlocking the enclosure, to prevent unauthorized changes to any of the parameters, such as Trip Speed Set Point, MPU Failed Set Point and Trip on MPU Failure.

Programming is done for each unit through a keypad and a two-line LCD display, located on that unit’s operator interface. The overspeed test frequency is adjusted using a potentiometer, also located on the front panel.