Reducing Arc Flash Hazard in 3Ø Pad Mounted Transformers and Other Safety Considerations

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/cm2 is threshold for 2nd degree burn • PPE requirements are intended to limit burns to “just curable” 2nd degree

3. PPE Categories 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 0 Category 1 Category 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. Ferraz Shawmut High Power Laboratory Newburyport, MA Three Phase Pad Mounted Distribution TransformerARC FLASH TESTING June 23, 2009

9. Distribution TransformerArc Hazard Case Study

10. Distribution TransformerArc 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 TransformerArc 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

13. Inside the Box

14. ERMCO’s DesignOutside the Box Made in the USA

15. Results

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 SENSESafety Features • Increased working space • Enhanced air flow helps cool workers in heavy clothing

18. ERMCO COMMON SENSESafety 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 SENSESafety Features • Conditioned edges to prevent tears in clothing and skin

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