Live Turbine Health

Digital signal processing (DSP) unit delivers
real-time turbine blade tip condition monitoring

Monitran Technology has developed a digital signal processing (DSP) unit for the real-time monitoring of turbine blade conditions.

The unit reflects ‘live’ blade health by providing traffic-light-type indicators: green for safe, amber for advisory and red for danger. Also, for each condition, there is a programmable output capable of switching up to 30V at 5A, which means the unit can be easily integrated into control circuitry and to provide an automatic shut-down of the turbine if necessary.

Donald Lyon, Monitran Technology’s Managing Director, comments: “Up until now, turbine blade health monitoring has required the capture of data, often with the turbine off-line, and then extensive and time-consuming data analysis. Our DSP unit affords real-time, in situ data analysis, allowing plant owners and other users of turbines to adopt predictive maintenance strategies, and to operate more cost-effectively. Also, if the unit is playing a role in the turbine’s control circuitry, it can reduce the risk of catastrophic failure if something does go wrong.”

The DSP unit has four channels which are each intended for use with an eddy current probe and suitable trigger circuitry (such as Monitran’s T3 unit) and processes data relating to blade-tip-to-casing clearance and by recognising any blade-to-blade lead or lag issues.

The use of all four channels supports the placement of sensors at approximately 90 degree intervals around the turbine’s casing. Lyon adds: “Investigatory work we conducted with QinetiQ indicated that blade deterioration can occur in less than a single revolution.”

A fifth channel on the unit is intended for a traditional accelerometer, so that vibration levels may also contribute to the overall picture of turbine health. In addition, all five channels feature digital (first in first out – FIFO) buffers for pre- and post-trigger recording, and can feed external digital recorders.


Once per revolution (OPR) signals are also provided; one input and four synthesised outputs.

The unit is in a standard DIN rail mount format, and measure 156 x 86 x 56mm (L, D and H respectively). It is available with the control panel either integral to the unit or as a separate item (say for wall-mounting). In addition, full remote monitoring and control of the unit is possible via multidrop RS454.