A thermal imaging survey involves capturing thermal images of electrical distribution equipment . The images are analysed to identify faults which have the potential to cause equipment failure and damage to property. A report is generated that identifies all of the equipment surveyed together with detail of any faults found.
Electrical thermal imaging surveys are non-intrusive, enabling inspections to be completed safely and efficiently, without interruption to your business operations. By having surveys completed on substation equipment the following benefits can be achieved:
- Reduction in breakdown maintenance costs
- An increased availability of insurance companies willing to provide cover
- Reduction in insurance premiums
- Reduction in risk mitigation contingency Budgets
- It is extremely fast and accurate
Substations call for a predictive approach to maintenance because a failure can be costly for end users in terms of lost production and revenues and lead to lower revenues for the utility from lost sales due to unreliable service. Since overheating as well as abnormally cool operating temperatures may signal the degradation of an electrical component, thermal imagers provide the predictive capabilities required for substation and switchgear maintenance.
In the power generation and distribution industries, the term substation is used in many ways. Various outdoor facilities ranging from switchyards at generating stations to equipment at utilities or at industrial facilities that switches or modifies voltage, frequency or other characteristics of primary power are called substations.
Predictive maintenance (PdM) helps ensure the quality of an end user’s electricity by enhancing the reliability of substations. PdM accomplishes this increased reliability by monitoring equipment over time in order to isolate conditions that indicate impending failure.
One set of tools for monitoring equipment in substations is Fluke’s handheld thermal imagers. Thermal imagers capture two-dimensional representations of the apparent surface temperatures of electrical components and other objects.
What to check?
For a detailed outline of maintaining substations and related switchgear assemblies, follow NFPA Standard 70B, Recommended Practice for Electrical Equipment Maintenance, Chapter 8: “Substation and Switchgear Assemblies”. That standard explains that in transforming primary power, substations may provide system protection, power-factor-correction metering and circuit switching in addition to changing voltage.
What to look for?
Following a thorough inventory of the equipment in a substation, scan the entire substation yard, saving images of any known or possible anomalies. Look especially for similar pieces of equipment under similar loading that are clearly operating at different temperatures. A good thermographic approach to substation maintenance is to create inspection routes that include all the substations owned by your utility or facility.
What represents a “red alert”?
Equipment conditions that pose a safety risk should receive the highest repair priority. Beyond that, NETA (InterNational Electrical Testing Association) guidelines say that when the temperature difference (T) between similar components under similar loading exceeds 15 C (27 F) immediate repairs should be performed.
What’s the potential cost of failure?
The costs associated with a failed electrical substation depend upon many factors including the number and types of customers affected.
Whenever you discover a problem using a thermal imager, use the associated software to document your findings in a report that includes a digital, visual-light image of the equipment and a corresponding thermal image. That is the best way to communicate any problems you found and to make any suggestions for correcting them.