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DEVELOPING AND IMPLEMENTING AN EFFECTIVE ELECTRICAL MAINTENANCE PROGRAM Part I: Selection Of A Testing Firm Part II: Developing Specifications Part III: Anatomy Of a Shutdown; Implementing The Program |
Wrapping it Up The insulation resistance testing on substation 1 kept us at the site for several hours longer than planned, however another situation occurred that is important. All work was completed with the exception of Substation 1 and it was time to call the utility to restore power. The facility wanted to have the power restored to the main high voltage switch but to leave all grounding equipment installed until all work was completed. The electrical contractor coordinated with the utility who energized their disconnect switch and left the site. About an hour went by before we completed our work on Substation 1 and we were ready to energize the facility. Grounding equipment was removed and all personnel were removed from the substations. The main switch was closed and the small crowd of us moved to the indoor distribution lineup. The voltmeter on the switchgear was not reading any voltage. Hmm, this was interesting. The facility utilized a proximity meter to determine that there was no power on any of the three phases. Wild thoughts race through your mind, did a cable blow, were fuses blown, did someone leave grounds installed, were fused installed? Utilizing the proximity meter we determined that the utility power was not available on the line side of the main switch. The utility was called to return to the site, this created another hour delay while they came. It turns out that a different crew energized the utility pad mount switch than had deenergized it earlier in the day. When the crew opened the switch in the morning, they placed an insulated barrier across the open blades to prevent inadvertent closure of the switch. When the crew arrived in the evening, they removed their tags and closed the switch. They hear the familiar banging of the switch closed and left. They did not remove the insulated barrier, so the switch closed against it but the contacts were not touching. Only one of the electrical contractor personnel was available and they did not verify power. Can blame be placed, sure, but the reality is there is a lot going on during a shutdown and mistakes can be made. This mistake proved to be an inconvenience and little more. Some of the identified problems were corrected during the maintenance; others required a follow-up visit. The following findings relate to a previous Tech Tip from the Powertronic, Inc. website. One condition not identified was that the insulation resistance problem, Finding #2, was compounded by rain that developed during the maintenance. One week later a completed report with all test and inspection data was provided to the electrical contractor and the facility. This was the first major shutdown for the facility in several years and many lessons were learned. My understanding is that this helped the facility better understand the coordination and demands of a major shutdown. This article outlines a shutdown of a major facility, but the procedures will be similar whether you have an industrial plant or commercial office building. Powertronic, Inc. is prepared to work with you and your specific needs in electrical testing, maintenance and power quality related issues. Handy References NETA Maintenance Testing Specifications, 1997 NFPA 70B Recommended Practice for Electrical Equipment Maintenance, 1998
NFPA 70E Standard for
Electrical Safety Requirements for Employee Workplaces, 1995
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Copyright (c) 2002 Powertronic, Inc. All Rights Reserved. |
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