Specialist Measurements For Turbine Supervisory

Differential Expansion Techniques

Whilst we offer large range probes and complimentary / ramp configurations for differential expansion the calibration can be complex and limited due to mechanical restrictions and temperature drift.

Our Mark Space technique operates on detecting movement in special plates attached to the turbine shaft. The shaft target pattern consists of a number of pairs of ‘teeth’ and ‘slots’ surrounding the shaft. When the shaft rotates, the voltage pulses produced by the proximity probe have a tooth to slot pulse width ratio dependent upon the axial relationship between the shaft pattern and the probe position.

Removing the absolute gap measurement and replacing it with a timing technique provides a repeatable and stable measurement over the full turbine speed range.

Shaft Position &
Thrust Wear

The position of the machine shaft or wear of the thrust bearing pads is critical measurement on rotating machines where rotors are employed in steam, gas or fluid handling.

The challenge is to provide a repeatable measurement utilising a proximity probe in a restricted space with an accuracy of better than 10um.

Sensonics strength is in designing and supplying the right probe with enough measurement range to allow for shaft float and to avoid unwanted side target interference. Along with sensor mounting arrangements that provide mechanical adjustment in conjunction with signal processing and calibration facilities we can offer the complete package.

Overspeed Protection

Overspeed protection is a key requirement for the critical rotating plants where the failure of the speed governing system can lead to damaging consequences.

Independent electronic speed monitoring and shutdown is essential to reduce this risk to an acceptable level and is a standard upgrade for mechanical systems that require a physical Overspeed test to demonstrate compliance. Sensonics have been providing high integrity Overspeed protection systems for many years with proven field reliability. The architecture of our system and facilities offered has been developed in conjunction with our customers, offering up to SIL-3 integrity in combination with a range of innovative proof test facilities.

Reverse Rotation

A reverse rotation incident with large machines such as turbines and pumps can be damaging to the driven plant (such as compressors or generators) and connecting systems.

The challenge with this measurement is to provide rapid detection of the turbine movement into this state (less than 2 revolutions) and generate the appropriate alarm.

Sensonics utilise a dual probe arrangement around a single or multi-tooth wheel and can advise on the precise sensor mounting and calibration to ensure correct detection with the signal processing equipment.