How OSHA's New Transient Overvoltage Requirements Affect Work Practices

摘要

This paper presents how the new Occupational Safety and Health Administration 29 CFR,§1910. 269 (OSHA 269) transient overvoltage (TOV) requirements affect a sample investor-owned utility (IOU) client's current safety approach distance to energized electrical equipment for transmission and distribution system. The new requirement could adversely impact many of the industry's current work practices as regulations go into effect January 31, 2016. It is anticipated that, if a utility solely utilizes the conservative TOV values supplied by OSHA without performing the appropriate an engineering analysis, then working distances will increase to values much greater than current working distances. The distances at high-voltage equipment may increase 50 percent or greater. Thus, prior to the deadline, utilities have the option of using the OSHA stipulation stating that, if the utility performs an engineering analysis using an electromagnetic transient program such as PSCAD or EMTP-RV, the amount of TOV could be reduced and consequently the MAD is decreased. In 2014, OSHA updated its 29 CFR Parts 1910 and 1926, commonly referred to as the "269 Standard," which entails implementing new OSHA rules for electric power generation, transmission, and distribution, electrical protective equipment. Specifically, OSHA's update affects many electric utilities' MAD to energized equipment greater than 72.5 kV. As stated in OSHA 269 Paragraph (c)(l)(ii) of§ 1926.960, OSHA "requires the employer to determine the maximum anticipated per-unit TOV, phase-to-ground, through an engineering analysis or assume a maximum anticipated per-unit TOV, phase-to-ground, in accordance with OSHA Table V-8, which specifies the following maximums for AC systems." Furthermore, if the TOV remains above OSHA's threshold, mitigation could be evaluated. A significant associated concern is that arc flash studies are dependent on TOV distances and consequently values will need to be recalculated to align with the TOV study. In other words, there is a resultant push-pull scenario between TOV and arc flash to help shape the future of safety distances to energized equipment. All substations over 69 kV will be needed to be analyzed for TOV and arc flash in order to be OSHA-compliant.