HEINZMANN Company Group

Engine & Turbine Management

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Optimal control technology for gas turbines

One of the most critical protection systems for rotating machinery. Overspeed control.

HEINZMANN developed the VOP O3 unit to monitor 3 speed probes with 2 out of 3 voting  to protect the machinery. Installed on many gas turbines and reciprocating engines alike. Gearboxes, turbos and other critical systems.




Overspeed Protection Unit

The VOP 03 is a Triple Voting Overspeed Protection Unit. It has 3 speed channels, each one monitored totally independently whilst the two out of three voting system considers the output from each channel. At least two of the channels must agree an over frequency and trip simultaneously for the overall voting contact to trip the turbine. Each channel can be tested while running and replaced, hot swap, while the machinery is running. The design provides protection from nuisance trips.

Technical data

  • Power supply: 18 ... 32 VDC @ 0.6 A
  • Operating temperature: - 20 ... +70 °C
  • Hot swap: Each module can be changed while unit is running
  • Speed range: 50 Hz ... 25kHz
More information

Data Sheet


  • Two out of three voting system to protect turbo machinery from overspeed
  • Accurate and repeatable to 0.1 %
  • The design provides protection from nuisance trips
  • Only individual channels will trip on fault, at least two channels have to agree on fault
  • Monitors three individual magnetic pickups in three independent modules whose voted output appears on a high integrity dry contact output
  • Easy to calibrate through maintenance program to set the trip frequency
  • Easily tested whilst operating through onboard frequency generator housed on board each of the three modules
  • Hermetically sealed relays and fully isolated frequency inputs guarantee quality and longevity and accuracy of speed measurement
  • Each unit fully isolated and only connected to the other channels via volt free voting relay contacts
  • Motherboard PCB is tracked in a voting system so two or more of the individual channel relays must sense overspeed before the common fault contact opens
  • Built-in test mode and signal generators allow the channel to be tested and tripped


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