1. Reducing Arc Flash Hazard in 3Ø Pad Mounted Transformers and Other Safety Considerations Presented at Western Energy Institute October 12, 2010 Christian Ouimet ERMCO Regional Sales Manager

2. 2009 Arc Flash Regulations Factors affecting risk include: Proximity Duration Arc in confined space or open air Must provide Personal Protective Equipment (PPE) to workers based on severity of arc flash energy 1.2 cal/cm 2 is threshold for 2 nd degree burn PPE requirements are intended to limit burns to “just curable” 2 nd degree

3. PPE Categories CategoryHeat GeneratedPPE Required 0≤ 2 cal/cm2 Long sleeve shirt Long pants Safety Glasses Non-melting untreated natural fiber 1≤ 4 cal/cm2 FR long sleeve shirt FR pants with a minimum arc rating of 4 OR Long pants - untreated denim cotton blue jeans of 12oz/yd2 OR FR coveralls - arc rating of 4 instead of FR shirt and pants Hard Hat 2≤ 8 cal/cm2 In addition to items listed in Category 1, use Face shield with a minimum arc rating of 8 Wrap-around guarding for forehead, ears and neck Could use flash hood suit 3≤ 25 cal/cm2 Cotton undergarments Non-melting long sleeve shirt and pants FR shirt and pants FR coveralls Hearing protection Safety glasses or goggles Hand protection Foot protection 4≤ 40 cal/cm2 Cotton shirt and pants FR shirt and pants Flash suit and hood Hearing protection Safety glasses Hand protection Foot protection Dangerous > 40 cal/cm2 No safe protection The Arc Flash categories, the heat generated, and the PPE required by NESC for each category is listed in the following chart:

4. Typical PPE Category 0Category 1Category 2 Category 3 Category 4

5. What Category are Distribution Transformers? IEEE provides a resource Arc flash calculations per IEEE 1584- 2002: “Formula for Estimation of Arcing Short Circuit Current” ERMCO engineers calculated arc flash Published a paper to show others how to use IEEE 1584-2002 ERMCO conducted arc flash testing Confirm IEEE 1584-2002 is a good approximation

6. 3Ø Pads Arc Flash Summary As a rule of thumb, most 300kVA and larger three phase padmount transformers fall into PPE Category 3 or higher.

7. 3Ø Pad Mounted Distribution Transformers Widely used in Electric Utility Industry Typically: Secondary conductors are open to the air Tight working conditions Compartment does not lend itself to working in bulky clothing Typical Industry Standard Low Voltage Box Compartment

8. Three Phase Pad Mounted Distribution Transformer ARC FLASH TESTING June 23, 2009 Ferraz Shawmut High Power Laboratory Newburyport, MA

9. Distribution Transformer Arc Hazard Case Study

10. Distribution Transformer Arc Flash Hazard Case Study Common Industry Transformer Application 500 kVA 12470GrdY/7200 Primary 480Y/277 Secondary Most commonly specified fuse protection for kVA size, 353C12

11. Distribution Transformer Arc Flash Hazard Case Study Full bolted fault limited only by transformer impedance 1 inch conductor gap per IEEE 1584 18 inch working distance per IEEE 1584 Low Voltage Terminal Arrangement per IEEE Std. C57.12.24-2004 Figure 11(a) Minimum Dimension

12. Inside the Box

14. ERMCO’s Design Outside the Box Made in the USA

15. Results Table 3 Summary of Arc Flash Calculations and Tests Enclosure Configuration Box or Open Predicted Incident Energy Cal/cm 2 Recorded Maximum Incident Energy Cal/cm 2 Box Configuration11.8712.36 Open Configuration8.015.58 Percent Reduction in Incident Energy 33% energy reduction 55% energy reduction

16. Arc Flash and ERMCO’s Open Cabinet 3Ø Transformer Arc flash regulations are intended to protect people from serious injury. ERMCO is not suggesting in any way to minimize safety protection or procedures. The ERMCO cabinet does offer enhanced safety over traditional “box” cabinets.

17. ERMCO COMMON SENSE Safety Features Increased working space Enhanced air flow helps cool workers in heavy clothing

18. ERMCO COMMON SENSE Safety Features Side and top can be moved away from the bushings No side or top for a lineman to accidentally touch a tool against With no side or top to ground against, the surface to initiate an arc is removed

19. ERMCO COMMON SENSE Safety Features Conditioned edges to prevent tears in clothing and skin

20. ERMCO COMMON SENSE Safety Features Improved visibility Tested at 35 times brighter!

21. Improving Transformer Safety ERMCO 3Ø has opening top & sides 55% reduction in arc flash energy Fewer ground planes Increased working space Enhanced air flow helps cool workers in heavy clothing Improved visibility Metal edges are rounded to prevent clothing tears & cuts

22. ERMCO ’ s Three Phase Pad Transformer It ’ s a Good Thing! www.ermco-eci.com ERMCO P. O. Box 1228 Dyersburg, TN 38025-1228 800-238-5587 731-285-9121 Made in USA Think Safety Good Things Happen When You Think Outside the Box!