{"id":14078,"date":"2016-05-26T21:31:40","date_gmt":"2016-05-26T21:31:40","guid":{"rendered":"http:\/\/www.iacdrive.com\/2016\/05\/26\/resistance-grounding-system\/"},"modified":"2016-05-26T21:31:40","modified_gmt":"2016-05-26T21:31:40","slug":"resistance-grounding-system","status":"publish","type":"post","link":"http:\/\/iacdrive.com\/?p=14078","title":{"rendered":"Resistance Grounding System"},"content":{"rendered":"<p><strong>Low Resistance Grounding: <\/strong><br \/>\n1. Limits phase-to-ground currents to 200-400A. <br \/>\n2. Reduces arcing current and, to some extent, limits arc-flash hazards <br \/>\nassociated with phase-to-ground arcing current conditions only. <br \/>\n3. May limit the mechanical damage and thermal damage to shorted <br \/>\ntransformer and rotating machinery windings. <br \/>\n4. Does not prevent operation of overcurrent devices. <br \/>\n5. Does not require a ground fault detection system. <br \/>\n6. May be utilized on medium or high voltage systems. GE offers low <br \/>\nresistance grounding systems up to 72kV line-to-line. <br \/>\n7. Conductor insulation and surge arrestors must be rated based on the lineto- <br \/>\nline voltage. Phase-to-neutral loads must be served through an <br \/>\nisolation transformer. <\/p>\n<p><strong>High Resistance Grounding: <\/strong><br \/>\n1. Limits phase-to-ground currents to 5-10A. <br \/>\n2. Reduces arcing current and essentially eliminates arc-flash hazards <br \/>\nassociated with phase-to-ground arcing current conditions only. <br \/>\n3. Will eliminate the mechanical damage and may limit thermal damage to <br \/>\nshorted transformer and rotating machinery windings. <br \/>\n4. Prevents operation of overcurrent devices until the fault can be located <br \/>\n(when only one phase faults to ground). <br \/>\n5. Requires a ground fault detection system to notify the facility engineer that <br \/>\na ground fault condition has occurred. <br \/>\n6. May be utilized on low voltage systems or medium voltage systems up to <br \/>\n5kV. IEEE Standard 141-1993 states that \u201chigh resistance grounding <br \/>\nshould be restricted to 5kV class or lower systems with charging currents <br \/>\nof about 5.5A or less and should not be attempted on 15kV systems, unless <br \/>\nproper grounding relaying is employed\u201d. <br \/>\n7. Conductor insulation and surge arrestors must be rated based on the lineto- <br \/>\nline voltage. Phase-to-neutral loads must be served through an <br \/>\nisolation transformer. <\/p>\n<p><strong>Conclusion: <\/strong><br \/>\n<a href=\"http:\/\/www.iacdrive.com\">Resistance Grounding Systems have many advantages over solidly grounded systems<\/a> including arc-flash hazard reduction, limiting mechanical and thermal damage associated with faults, and controlling transient overvoltages. High resistance grounding systems may also be employed to maintain service continuity and assist with locating the source of a fault. <br \/>\nWhen designing a system with resistors, the design\/consulting engineer must consider the specific requirements for conductor insulation ratings, surge arrestor ratings, breaker single-pole duty ratings, and method of serving phase-to-neutral loads.<\/p>\n","protected":false},"excerpt":{"rendered":"<p><strong>Low Resistance Grounding: <\/strong><br \/>\n1. Limits phase-to-ground currents to 200-400A. <br \/>\n2. Reduces arcing current and, to some extent, limits arc-flash hazards <br \/>\nassociated with phase-to-ground arcing current conditions only. <br \/>\n3. May limit the mechanical damage and thermal damage to shorted <br \/>\ntransformer and rotating machinery windings. <br \/>\n4. Does not prevent operation of overcurrent devices. <br \/>\n5. Does not require a ground fault detection system. <br \/>\n6. May be utilized on medium or high voltage systems. GE offers low <br \/>\nresistance grounding systems up to 72kV line-to-line. <br \/>\n7. Conductor insulation and surge arrestors must be rated based on the lineto- <br \/>\nline voltage. Phase-to-neutral loads must be served through an <br \/>\nisolation transformer. <\/p>\n<p><strong>High Resistance Grounding: <\/strong><br \/>\n1. Limits phase-to-ground currents to 5-10A. <br \/>\n2. Reduces arcing current and essentially eliminates arc-flash hazards <br \/>\nassociated with phase-to-ground arcing current conditions only. <br \/>\n3. Will eliminate the mechanical damage and may limit thermal damage to <br \/>\nshorted transformer and rotating machinery windings. <br \/>\n4. Prevents operation of overcurrent devices until the fault can be located <br \/>\n(when only one phase faults to ground). <br \/>\n5. Requires a ground fault detection system to notify the facility engineer that <br \/>\na ground fault condition has occurred. <br \/>\n6. May be utilized on low voltage systems or medium voltage systems up to <br \/>\n5kV. IEEE Standard 141-1993 states that \u201chigh resistance grounding <br \/>\nshould be restricted to 5kV class or lower systems with charging currents <br \/>\nof about 5.5A or less and should not be attempted on 15kV systems, unless <br \/>\nproper grounding relaying is employed\u201d. <br \/>\n7. Conductor insulation and surge arrestors must be rated based on the lineto- <br \/>\nline voltage. Phase-to-neutral loads must be served through an <br \/>\nisolation transformer. <\/p>\n<p><strong>Conclusion: <\/strong><br \/>\n<a href=\"http:\/\/www.iacdrive.com\">Resistance Grounding Systems have many advantages over solidly grounded systems<\/a> including arc-flash hazard reduction, limiting mechanical and thermal damage associated with faults, and controlling transient overvoltages. High resistance grounding systems may also be employed to maintain service continuity and assist with locating the source of a fault. <br \/>\nWhen designing a system with resistors, the design\/consulting engineer must consider the specific requirements for conductor insulation ratings, surge arrestor ratings, breaker single-pole duty ratings, and method of serving phase-to-neutral loads.<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[67],"tags":[],"class_list":["post-14078","post","type-post","status-publish","format-standard","hentry","category-iacdrive_blog"],"_links":{"self":[{"href":"http:\/\/iacdrive.com\/index.php?rest_route=\/wp\/v2\/posts\/14078","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/iacdrive.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/iacdrive.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"http:\/\/iacdrive.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=14078"}],"version-history":[{"count":0,"href":"http:\/\/iacdrive.com\/index.php?rest_route=\/wp\/v2\/posts\/14078\/revisions"}],"wp:attachment":[{"href":"http:\/\/iacdrive.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=14078"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/iacdrive.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=14078"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/iacdrive.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=14078"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}