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3 year warranty

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De-energize-to-Trip Unit 9905-874 from Woodward ProTech 203 Overspeed Protection. 24Vdc Input, Lockable Enclosure, and a Trip Alarm and LED.



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  • Part Number: 9905-874
  • SKU: 9905874WO
  • Manufacturer: Woodward
  • Series: ProTech 203 Overspeed Protection

9905-874 Technical Specifications

Dimensions W482.6 x H310.4 x D142.7mm
Features MPU Failure Indication
Humidity Standards MIL-STD-810D, Method 507.2, Procedure II.
Input Voltage 120 Vac/dc (2), 220 Vac (1)
Keypad/Display (3) Keypads, Knobs, and Displays
Manual 85191
Manufacturer Woodward
Model De-energize-to-Trip
Operating Temperature –25 to +60 °C (–13 to +140 °F)
Weight 16lbs (7Kg)

Product Description

9905-874 is an overspeed protection system with three speed-sensing units that continually monitor and calculate prime mover speed. The three units are all enclosed in the same locked enclosure, which meets NEMA 4 and IP 65 standards. Each unit has its own power supply and operator interface. In model 9905-874, two of the three units have a 120 Vac/dc power supply, and the third unit has 220 Vac supply. The two 120 Vac/dc units have a voltage range of 88–132 Vac/90–150 Vdc, 7.25 W. The 220 Vac supply unit has a voltage range of 180–264 Vac, 7.25 W.

Each speed-sensing unit uses its own magnetic pickup (MPU) and performs its own speed calculation. From this, a hardware two-out-of-three vote is performed. If an overspeed condition is detected, a trip relay is activated. This method of hardware vote also permits testing or replacement of any of the three units without having to take the prime mover offline.

The three operator interfaces on the 9905-874 enclosure each have an LCD, keypad, and LEDs to indicate the functional status of the corresponding unit. There are separate LEDs to indicate different issues, and some problems, such as a tripped unit, may also be alerted with an alarm output as well.

Model 9905-874 is manufactured by Woodward as part of the company’s ProTech 203 Overspeed Protection System series. This model is one of the de-energize-to-trip versions available. More information can be found in the company’s manual 85191 (version B).

Reviews For 9905-874

Internal Review

The engine, turbine, or other types of prime mover should be equipped with the Overspeed Shutdown Device 9905-874 to protect against runaway or damage to the prime mover with possible personal injury, loss of life, or property damage. - Tech Team

Repair Services For 9905-874

Type Lead Time Price Action
Repair Service 1-2 weeks $4677

Our highly skilled technicians can repair your 9905-874. All of our repairs come with a 3 Year AX Control Warranty. Please contact us for additional information about our repair process. To receive the repair pricing and lead time listed above please process your repair order via our website. The following repair options may be available upon request:

  • 48-72hr Rush Repair
  • Detailed Repair Reports
  • AX Control Certificate of Warranty

AX Control Warranty Info

All products we sell are backed by our unparalleled warranty. A warranty certificate will be provided with your order upon request.
All PLCs, HMIs, and Turbine Control Boards: 3 Years
All AC/DC and Servo Drives: 2 Years
All Motors: 1 Year
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9905-874 Manuals, White Papers, Data Sheets, and Troubleshooting