9905-878 Image One
3 year warranty

9905-878 Image 1
9905-878 Image 2
9905-878 Image 3
9905-878 Image 4


    Varying star amount pictures Varying star amount pictures Varying star amount pictures Varying star amount pictures Varying star amount pictures
  • 5.00 (2)
  • Click a star to rate this product
    Varying star amount pictures Varying star amount pictures Varying star amount pictures Varying star amount pictures Varying star amount pictures
  • 5.00 (2)
  • Click a star to rate this product
The 9905-878 model is a De-Energize-to-Trip model as part of the ProTech 203 Overspeed Protection System produced by Woodward. This model operates on 24 VDC. The enclosure on the 9905-878 unit is NEMA 4X.



Sell Surplus: Have a 9905-878 to sell? Sell Now
Exchange Credit: Learn more about our exchange credit program
  • Part Number: 9905-878
  • SKU: 9905878WO
  • Manufacturer: Woodward
  • Series: ProTech 203 Overspeed Protection

9905-878 Technical Specifications

Part Number 9905-878
Series ProTech 203 Overspeed Protection
Manufacturer Woodward (Manual 85191)
Model De-energize-to-Trip
Keypad/Display 3 Displays and Keypads
Standards NEMA 4X, IP54
Input Voltage 24 Vdc = 18–32 Vdc, 7.25 W
Operating Temperature –13 to +140 °F
Features Key Lock
Dimensions W19in x H12.244in x D5.62in (with knobs and key)
Weight Less than 17 lbs

Product Description

Woodward’s ProTech 203 model 9905-878 is designed for reliable overspeed protection. This model is just one of the many ProTech 203 models. Two versions have the same supply in units A, B, and C. One of them is the 9905-878 unit, and the other is the 9905-869, which has a NEMA 4 enclosure, making the two different. This two-out-of-three hardware vote device permits normal operations with an accurate output provided two of the three speed-sensing units are online, which permits hot replacement, and testing of individual units while the prime mover is online, and continuing operations in the event one of the units is tripped. An inadvertent turbine trip will not occur from a single MPU failure.

Each of the three speed-sensing units within model 9905-878 has a 24 Vdc power supply (18–32 Vdc, 7.25 W voltage range). Each one produces +5 V and +24 V, which is isolated from the input voltage. All three units are in the same enclosure. The locked enclosure of this ProTech 203 model is NEMA 4X certified as long as it uses the optional stainless steel hubs.

This is a de-energize-to-trip model. It has LED indicators on each unit to alert operators of a tripped unit, an MPU failure, or a CPU failure. There is also an alarm output to notify of a tripped unit.

A tripped unit must be reset (or the power cycled) before being brought back online, and each unit must be reset before starting the turbine. The 9905-878 overspeed protection system includes a convenient remote reset feature.

The installation and operation manual for models 9905-878 is Woodward’s ProTech 203 Overspeed Protection System Manual 85191 (version B). In this manual, you can find additional product specifications, installation location requirements, programming instructions, and more.

Frequently Asked Questions about 9905-878

Are there any reasons why the 9905-878 model is better to use than other ProTech 203 models?

One of the main reasons the 9905-878 is so useful is that it is used to help with general safety and will ensure that the prime mover trips in the event of loss of power. For other ProTech 203 models, especially Energize-to-Trip models, they may not trip if a loss of power occurs, and the 9905-878 model and other De-Energize-to-Trip models ensure that the attached prime mover will trip to ensure that personal injury or property damage does not occur. For more information on why the De-Energize-to-Trip model is better to use than the Energize-to-Trip models refer to the attached Woodward manual.

What happens when the attached prime mover attached to the 9905-878 model does not start?

If the attached prime mover does not start when connected to the 9905-878 model, it is likely that the attached units do not have power. To fix this, make sure that all of the attached De-Energize-to-Trip models have power and that the wiring, power supply fuses, and power sources are all attached correctly.

Reviews For 9905-878

Internal Review

There are two versions of the De-Energize-to-Trip models that operate on the same power supply of 24 VDC. The main difference between the two models is the enclosure type. This model is more enhanced due to the NEMA 4X enclosure. For more information on the differences, refer to the attached Woodward Manual. - AX Control Tech

Repair Services For 9905-878

Type Lead Time Price Action
Repair Service 1-2 weeks $4164

Our highly skilled technicians can repair your 9905-878. 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
Learn More

9905-878 Manuals, White Papers, Data Sheets, and Troubleshooting