Astech Electronics  
Instrumentation & Rotary Telemetry Consultancy and Design (+44) 1420 22689
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Gas Turbine

Rotary telemetry is used for collection of strain and thermocouple data from gas turbine rotors in both R and D and validation programmes. Astech design complete systems for power generation, aircraft jet engines and marine propulsion gas turbines.  Reliable performance is checked by spin testing transmitters at 140°C and verifying data quality over several days.                     *Click on thumbnails to enlarge

Transmitters and Carriers

Gas turbine applications frequently require large numbers of strain and temperature measurements - and this means installation of a number of transmitters plus inductive power hardware, into whatever space is available.

(Click on thumbnails to enlarge)

Wedge design strain transmitter 35mm x 26mm x 6mm giving high density packing

21 wedge design transmitters in titanium carrier 125mm dia x 46mm axial.

21 transmitters and carrier installed in gas turbine.


Flat wedge design strain transmitter 40mm x 20mm x 8.5mm giving high axial density packaging

14 thermocouple channel transmitter. Flat wedge form for high axial density packaging.

Titanium carrier 208mm diameter x 11mm for flat wedge transmitter.


12 flat wedge design strain transmitters in aluminium housing

Aluminium carrier housing nine 40mm x 15mm diameter cylindrical design strain transmitters.

5 25kHz B/W strain transmitters in aluminium carrier - blade vibration investigation.


18 rectangular design single channel strain transmitters, 27kHz bandwidth.  Housed in 175mm diameter titanium carrier.  Operated at 27,000 RPM and 145°C.

32 rectangular design multi-channel strain and thermocouple transmitters in 190mm diameter titanium ring form carrier.  Operated at 27,000 RPM and 145°C.  A central hub is temporarily fitted for spin testing purposes.

Set of 40 transmitters on a spin test carrier - 60 strain gauge and 160 thermocouple channels.
Part of 840 channel system for power generation Gas Turbine validation.

One of four 0.86M diameter transmitter carrier rings used on a massive 860 channel systems supplied to General Electric for validation of the 9H power generation gas turbine.

A 2 channel strain transmitter as used in the General Electric 9H system.  Inductive power pickup and signal transmission antenna are incorporated into the underside.

Demodulators and Decoders

All demodulator systems are based upon the universal 19" rack x 3 units high caseframe, with plug-in modules incorporated according to system size and complexity. The smallest systems used for gas turbine applications tend to be in the range 10-15 channels and for these, simple stand-alone demodulator modules are available.

For larger systems of up to 1024 channels, single, 2 and 5 channel demodulators may be set-up and operated via remote control, using the inductive power supply transmit setup data commands to the transmitters.  A laptop or P.C will generally be used as an input and local display.

Summary of available commands to transmitters:

  • ■ Activate shunt calibration - typically 1kHz or 10kHz
  • ■ Set excitation current (single gauge strain transmitters)
  • ■ Turn off excitation current
  • ■ Set excitation voltage(strain gauge bridge transmitters)
  • ■ Null inputs to zero (strain gauge bridge transmitters)
  • ■ Adjust input sensitivity
  • ■ Turn on simulated triangle or square waveform (check A/D linearity)
  • ■ Fine tune transmitter carrier frequency

Summary of available commands to demodulators:

  • ■ Set tuned frequency
  • ■ Set capture range of A.G.C
  • ■ Set to auto-tune or manual fine tune
  • ■ Adjust zero
  • ■ Fine adjustment of output scaling

 Typical Astech "Monitel" control software display showing setup and status for 27 x 2 channel strain transmitters and 1 x 15 channel thermocouple transmitter.


Demodulator Examples

PCM Telemetry Controller Module TC3

Two 256 channel demodulator / decoders - part of 1024 channel system for Gas Turbine validation.

2 Channel Strain Gauge Demodulator Module SGDM.


16 Strain and 16 Thermocouple Channel Demodulator System.

Multichannel Thermocouple Demodulator Module TCDM. Outputs are in USB and RS 232 serial formats.

80 Channel strain and temperature demodulator system.


Inductive power supply drive amplifier for large systems.

256 channel Gas Turbine System ready for shipping.

80 channel Gas Turbine System ready for shipping.