Computerised condition monitoring at power station

Engineers from Enron Power Operations use a portable data collection unit called the SKF CMVA60 Microlog to collect information on equipment throughout Teeside Power Station

When charged with maintaining the efficient and continuous operation of a power station, condition monitoring is not an issue that engineers leave to chance.

At Teeside Power Station, engineers from Enron Power Operations Limited have responsibility for the entire plant, including all commissioning and maintenance activities.

With eight gas turbines, two steam turbines and a new black start engine on site, there is an enormous amount of moving machinery, much of it essential to the electricity generating process.

While unscheduled downtime is kept to a minimum, all the most critical parts of the plant are covered by redundancy back-up equipment.

If any part of the machinery fails, the repair or replacement must be immediate.

Clearly, if a piece of equipment shows a trend towards failure, then during the time it takes to effect a repair, the operational unit has no back-up.

For this reason, there are two condition monitoring systems in place.

The first is a large scale Bentley Nevada system which is used to monitor all the major turbogenerator sets.

The other, more flexible system is an SKF computerised condition monitoring solution used on all ancillary devices, such as fans, pumps, motors and gearboxes.

Even air compressors and firefighting equipment are checked with the SKF system.

The SKF condition monitoring system is a portable data collection unit called the SKF CMVA60 Microlog and is used to collect information on equipment throughout the Teeside plant.

The data is analysed on a PC that runs SKF PRISM4 condition monitoring software to create trending, historical and diagnostics charts and graphs.

One example of how the SKF system has proved beneficial is illustrated by an application on a cooling tower fan.

It has been known for some time that periodically, the interstage shaft of a three stage gearbox and main bearing must be replaced.

However, using the SKF system, it was discovered that it is the shaft that breaks down, only causing bearing failure as a consequence.

Now, the condition of the shaft is diligently monitored using the SKF equipment to predict the time for routine maintenance.

The SKF Microlog has proved itself to be particularly useful for collecting real-time data.

For instance, when a large fan is being run up, the Microlog is used to check for imbalances, gearbox problems and so forth.

Measurements in this case are taken from the gearbox and the motor shaft, and compared with a baseline (model) indicating what fault conditions show.

An additional application for the SKF equipment is for verifying data being collected by the Bentley Nevada monitoring system.

By connecting the Microlog to the Bentley system, the readings can be checked both for accuracy and to ensure that they are being interpreted correctly.

A typical example of this type of use is when plant operators occasionally detect external vibrations that, while accepted by the Bentley system, are perceived by them to be out of the norm.

The SKF Microlog is used to confirm that the vibration levels are acceptable.

Enron's Mechanical Technician Jim Shadforth said, "we get good support from SKF".

He added, "SKF's experts are readily available to assist us and when we've encountered a problem, someone endeavours to visit as soon as possible.

For instance, we confronted a variety of new parameters to measure on some cooling tower fans and SKF's experience and knowledge of similar applications was most helpful".

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