Thermographic Survey as part of a Predictive Maintenance Program

Thermographic?? What is it?

A thermographic survey is performed with a specialized camera that can take pictures in the Infrared spectrum. The Infrared scan will show the thermal reading of an object either hot or cold, without requiring operators to interrupt the normal operation of equipment. The readings can be displayed in either Celsius or Fahrenheit.

Predictive Maintenance Programs

Companies use predictive maintenance programs to identify potential failure of components before the components have actually failed. The program allows the maintenance staff to repair components during scheduled repair window by knowing that a piece of equipment is approaching its failure point. This allows the maintenance staff to be proactive instead of being in a reactive mode of fixing equipment only when it fails. By using this method, the maintenance staff can have on hand the proper tools and replacement parts needed to repair a piece of equipment without the equipment having to be out of service for extended periods of time.

Depending on the type of equipment being analysed, the equipment may require different types of testing. Thermographic surveys can improve the predictive nature of maintenance programs by showing where the equipment is generating hot or even cold spots that are not normal in the operation of the equipment. A thermographic survey using a non-evasive testing routine allows the equipment to remain on line in an operational mode. Once a potential problem has been identified, further testing by others means may be required to pinpoint the cause of the failure. With the data from the thermographic survey, during a scheduled maintenance window, the maintenance staff can then perform other types of testing that may require the equipment to be taken off line and test equipment connected. This allows the maintenance staff to make better informed decisions and to ensure that potential problems are addressed in a timely manner.

Planning for a Thermographic Survey

What equipment needs to have a thermographic scan performed on it? This can be a very hard question to answer. Two pieces of equipment can readily be identified. They are equipment that has recently been started up and equipment that is going to be shut down for an extended period of time.

Equipment that has recently been started up should always have a thermographic scan performed on them. This will provide two pieces of information. The first piece of information is that the equipment was installed properly and is working correctly. The second piece of information is what will be used over the life of the equipment and that is a thermographic base line of the equipment. In future thermographic surveys, the base line will be used to determine how much deviation has accrued and to point out excessive deviation that needs to be corrected.

By performing a scan on equipment that is going to be shut down, it allows the maintenance staff to verify that everything is operating properly before the shut down and requires no follow up testing. If a problem is identified then the maintenance staff can schedule repair during the shutdown period and avoid having the equipment off line for repairs when the equipment is scheduled to be online.

Other types of equipment that should be added to the thermographic survey are equipment that is never removed from service for maintenance due to the critical nature of the equipment. This real important for checking cable connections and bus bars in electrical equipment and switchboards and to verify that all connections are tight and there is no corrosion causing a poor connection.

Additional types of equipment that may require a scan to be performed on it, is equipment that is exposed to vibration or mechanical movement. By conducting the thermographic survey, it can reveal both electrical and mechanical heating caused by loose connections, misalignments and worn out bushings.

UPS batteries can have a thermographic scan performed during a battery run down. The thermographic scan will help0 identify batteries with poor connections on the battery posts. A thermographic scan may also reveal hot spots or cold spots inside the battery showing that the battery is not performing as it should.

Power distribution units should have thermographic scans performed on them yearly. These units carry a lot of different loads and usually are never taken off line for maintenance. Not only can loose connections on the panel board breakers show up but the thermographic scan can show that the breakers are reaching a point where they are going to fail by showing hot spots internally in the breakers. The scan will also be able to inspect the transformer for any problems.

Once the equipment has been identified as requiring a thermographic scan then the staff needs to determine the time frame on when the scan should be performed. Yearly thermographic surveys should be performed as a minimum. Some equipment may require semi-annual surveys or more frequently based on the critical nature of the equipment or the failure rate of the equipment. Depending on the schedule for the operation of the equipment, some equipment may only be able to be done at certain times of the year and may require a separate visit by the thermographer. It is important to remember that the equipment having the theomorphic scan needs to be operating under load for a period of time so that an accurate thermal reading can be taken. Once a thermographic survey has been performed and corrective action has taken place, another scan of the noted problems should be done to verify that the problems have been corrected and that no other problems still exist.