Applications for Thermal Imagers

Substations and

Application Note

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 capa- bilities required for substation and switchgear maintenance.

In the power generation and conditions that indicate impend- power-factor-correction metering distribution industries, the term ing failure. The goal is to deter- and circuit switching in addition substation is used in many mine whether corrective action to changing . Substations ways. Various outdoor facilities is required and, if so, to take that and switchgear inherently operate ranging from switchyards at action before equipment fails. at high . NFPA standard generating stations to equip- One set of tools for monitor- 70E provides additional specific ment at utilities or at industrial ing equipment in substations is guidance on procedures and the facilities that or modi- Fluke’s handheld thermal imag- level of personal protective equip- fies voltage, frequency or other ers. Thermal imagers capture ment required when inspecting characteristics of primary power two-dimensional representations substations. Thermal inspectors are called substations. of the apparent surface tempera- typically inspect , Predictive maintenance (PdM) tures of electrical components regulators, switches, circuit break- helps ensure the quality of an end and other objects. The cameras ers and among other user’s electricity by enhancing now include IR-Fusion®*, a tech- components. the reliability of substations. PdM nology that fuses a visual, or vis- The time of day is an important accomplishes this increased reli- ible light, image with an infrared factor in collecting thermal images ability by monitoring equipment image for better identification, of substation components. Read- over time in order to isolate analysis and image management. ings in the stillness of early morn- The dual images are accurately ing may avoid the effects of solar aligned at any distance height- reflections and wind, which can ening details so problems are skew temperature readings. How- easier to spot. ever, in pre-dawn hours loads are *The Fluke Ti20 comes with InSideIR™ generally lighter and problems less analysis and reporting software with free updates for the life of the product. detectable. The training and expe- rience of the thermographer may What to check and also affect when outdoor IR scans when? should be performed. For a detailed outline of main- What to look for? taining substations and related switchgear assemblies, follow Following a thorough inventory of NFPA Standard 70B, Recom- the equipment in a substation, scan mended Practice for Electrical the entire substation yard, saving Equipment Maintenance, Chap- images of any known or possible ter 8: “Substation and - anomalies. Look especially for gear Assemblies.” That standard similar pieces of equipment under explains that in transforming similar loading that are clearly For equipment that always has primary power, substations operating at different temperatures. a high operating temperature, establish a baseline or standard may provide system protection, acceptable temperature range to compare readings to.

For more information on Thermal Imagers go to www.fluke.com/thermography tion) guidelines say that when What’s the potential the temperature difference (T) cost of failure? between similar components under similar loading exceeds The costs associated with a 15 °C (27 °F) immediate repairs failed electrical substation should be performed. NETA also depend upon many factors recommends the same action including the number and types This thermal image shows hot secondary connections on the of customers affected. One . when the∆T between a compo- nent and ambient air exceeds source*, estimates the average 40 °C (72 °F). hourly cost of downtime across Following this line of thinking, all industries at nearly $950,000. one way to categorize mainte- nance tasks and flag equipment Follow-up actions urgently needing repairs is to Whenever you discover a problem monitor substation equipment for using a thermal imager, use the specific degrees of temperature associated software to document rise above established reference your findings in a report that points. Knowledgeable technical, includes a digital, visual-light safety and maintenance person- image of the equipment and a nel might establish these limits to corresponding thermal image. Examine transformers, comparing similar connections under range from “continue to monitor” That’s the best way to communi- similar loads. to “correct immediately,” with cate any problems you found and other levels of action such as to make any suggestions for cor- “schedule maintenance” or “repair recting them. Following corrective A good thermographic as soon as possible” in-between. action, a new thermal image can approach to substation main- This approach has been suc- be used to assess the effective- tenance is to create inspection cessful when reference points ness of repairs and evaluate the routes that include all the substa- take into account the differences materials and techniques used. tions owned by your utility or between line-of-sight scans With this information, you can facility. On a computer, save ther- (e.g., metal-to-metal contacts in continuously improve your main- mal images of each substation switchgear) and non-line-of- tenance program for substations. component and track temperature sight situations (e.g., the internal components of transformers), *IT Performance Engineering and Measure- measurements over time. That ment Strategies: Quantifying Performance way, you’ll have baseline images where heat is dissipated or and Loss, Meta Group, Oct. 2000; Fibre obscured from the direct view Channel Industry Association as found on the with which to compare later Web site of the Association of Contingency images. Doing this will help you of the thermographer and the IR Planners, Washington State Chapter: www. determine if temperature levels camera. In a non-line-of-sight acp-wa-state.org. are unusual and, following correc- scan, the actual operating tem- bag in place. tive action, help you determine if perature will be much higher maintenance was successful. than the IR camera registers, so the reference points that What represents a signal what corrective action “red alert?” to take must be much lower. Also, abnormally cool as well Equipment conditions that pose as abnormally hot components Fluke. Keeping your world a safety risk should receive should be included in the mix. up and running.® the highest repair priority. Beyond that, NETA (InterNa- tional Electrical Testing Associa- Fluke Corporation PO Box 9090, Everett, WA 98206 U.S.A. Fluke Europe B.V. PO Box 1186, 5602 BD Eindhoven, The Netherlands For more information call: An imaging tip: In the U.S.A. (800) 443-5853 or Fax (425) 446-5116 Consider performing IR scans of substations during the winter and early spring In Europe/M-East/Africa +31 (0) 40 2675 200 or Fax +31 (0) 40 2675 222 months rather than during the summer when loading is the highest. In the In Canada (800)-36-FLUKE or summer, it is more difficult for maintenance personnel to get authorization for Fax (905) 890-6866 shutdowns for repairs. However, during peak loading in the summer is when From other countries +1 (425) 446-5500 or Fax +1 (425) 446-5116 equipment is most likely to fail. Repairs made in winter and spring will put Web access: http://www.fluke.com equipment in tiptop condition to meet the demands of summer. ©2005, 2007 Fluke Corporation. Specifications subject to change without notice. Printed in U.S.A. 12/2007 2542593 A-EN-N Rev B

2 Fluke Corporation Thermal Applications: Substations and Switchgear