Condition Monitoring Systems

Turbine Supervisory Systems

In the Turbine Supervisory world, Knowledge is Power!

Machinery is under stress

In modern power plants, units are often cycled much more frequently than originally designed for; this may be to conserve fuel or to meet load scheduling or environmental requirements, but as a result, rotating machinery is typically under higher levels of mechanical stress than in previous times, and much more detailed machinery condition and performance information is required in order to operate safely and efficiently.

On most rotating equipment, shaft vibration and position information – such as Rotor Expansion, Casing Expansion and Differential Expansion – provides a good indication of a machine’s normal operating fingerprint or signature, which is required in order to recognize any changes which might occur with time. Early recognition and analysis of changes is vital and allows for well informed decisions to be made, for example, whether to shut down immediately or to wait until the next scheduled outage. However, modern instruments can provide a great deal more information relating to the condition of the machine components, including detecting broken or cracked shafts, seal rubs, looseness or misalignment. These conditions can be detected and monitored as they develop, leading to informed operational and maintenance decisions.

Costs and Benefits

The benefits of a structured Condition Monitoring program supported by well financed and carefully designed TSI systems – including sensors, signal conditioning, data acquisition and analysis software and tools – are well established and documented.

In a detailed study on three identical plants back in the 1970’s, the costs of the three main types of maintenance program indicated that a ‘Run-to-failure’ maintenance program might cost $12-$15 per hp per year and a ‘Preventive’ or ‘Scheduled’ maintenance program might be $8 – $10 per hp per year. But a ‘Predictive’ maintenance program might be in the region of $6 – $8 per hp per year, representing significant cost savings when one considers the large horse-power installed on many sites.

These figures have recently been updated by EPRi, and indicate that for every dollar spent on ‘On Condition’ based maintenance, $1.47 would have been spent on ‘Planned’ or ‘Scheduled’ maintenance and $1.89 would have been spent on a ‘Run-to-failure’ or ‘Breakdown’ maintenance program.

These numbers speak loudly for themselves!

What is TSI ?

Turbine Supervisory Instrumentation (TSI) typically provides plant owners, operators and maintenance groups with the data required for conducting Condition Monitoring studies and structured Predictive Maintenance programs on steam turbine machinery as would usually be found in large power generating plants.

Increased use of TSI and the related availability of detailed knowledge as to the condition of the machinery, typically reduces operating costs by:

  • Reducing the time required to start a turbine
  • Extending the time intervals between scheduled outages
  • Reducing the time taken for repairs by enabling improved parts
  • Provisioning and manpower planning
  • Providing increased diagnostics and fault finding capabilities
  • Giving early warning of developing problems
  • Providing automatic shutdown of the units
  • Preventing minor problems from becoming catastrophic failures
  • Preventing collateral damage as a result of such a failure
  • These benefits translate into hard cash when one considers the size of these generating sets and the associated cost of lost production due to unexpected shutdowns, which often dwarfs the other costs of any mechanical repair.

But technical product developments, economic necessities and environmental constraints have meant that the operational and financial benefits of conducting a structured Condition Monitoring and Predictive Maintenance programs are no longer the sole domain of large Power or Process plants.

Condition Monitoring is increasingly successfully adopted in other industries and locations, including Paper Mills, Metal Processing Plants, Hydro Power Plants and for the new generations of Wind Turbines. This is of course particularly relevant if and when the monitored machine is vital or critical to the financial and operational success of the plant or organization.

TSI equipment is available in all flavors, colors and capabilities, since in this business, one size definitely does not fit all.

Therefore, careful selection of products and design of the overall system is vital to the success of the scheme. Indeed, many schemes fail due to incorrect product selection, inadequate design, weak integration and lack of testing, all of which sounds easy on paper, but in reality, it can be a complex process requiring time and expertise resources which many companies and organizations simply do not possess.