9907-344

About the 9907-344

The speed-sensing units of ProTech model 9907-344 are in an enclosure that meets NEMA 4 and 4X standards for North America, and IP54 for Europe. This enclosure is locked and a key switch controls whether the units are in MONITOR mode or PROGRAM mode. Parameters may be programmed, and units may be tested in PROGRAM mode. MONITOR mode only allows viewing of device tunable parameters, as well as Present Speed and Peak Speed.

Each of the three units actuates two voter relays and is connected in a two-out-of-three-vote configuration. Apart from that, they function independently to monitor prime mover speed. This is done with magnetic pickups (MPUs) that sample prime speed every 5 ms. The speed-sensing frequency range of this model is 100 Hz to 32 kHz.

Woodward ProTech overspeed protection systems are available in both energize-to-trip and de-energize-to-trip models with various power supply configurations. Model 9907-344 is a 24 Vdc (18–32 Vdc, 5.12 W) energize-to-trip system. Other ProTech models are also available from AX Control.

ProTech model 9907-344 units each have an operator interface on the front panel of the enclosure. These include a two-line LCD display, keypad, potentiometer, and both visual and audible alarms. Visual alarms consist of error messages on the LCD and LED indicators. The LEDs indicate issues such as MPU failure, CPU failure, or a tripped alarm. Audible alarm outputs indicate issues that may require attention, such as a tripped unit or an MPU loss of power.

Before starting the turbine and after a trip, units must be reset, which can be done from a remote location through the device’s remote reset function.