{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/9888"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/9888","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Improvement of Ground-Fault Relaying Selectivity through the Application of Directional Relays to High-Voltage Longwall Mining Systems","abstract":"The continuing trend toward larger longwall mining systems has resulted in the utilization of higher system voltages. The increase in system voltage levels has caused the industry to face complexities not experienced with the lower-voltage systems. One such complexity arises from the larger system capacitance that results from the outby configuration commonly used on 4,160-V longwall power systems. Simulations show that during a line-to-ground fault, the larger system capacitance can cause a situation where the ground current sensed by the ground-fault relays in unfaulted circuits is greater than the mandated ground-fault relay pick-up setting. Simulations show that ground-fault relaying selectivity is potentially lost as a result of this situation. Two alternatives were identified which could improve ground-fault relaying selectivity. They are: the application of a directional relaying scheme and increasing the ground-fault relay pick-up setting. It was determined that directional relays have an application to high-voltage longwall power systems as the ground current sensed by the relay in the unfaulted circuits is out of phase with the ground-fault current sensed by the relay in the faulted circuit. Furthermore, it was determined that raising the ground-fault relay pick-up setting by a factor of eight would also improve ground-fault relaying selectivity. A safety analysis considering the potential for electrocution and the power dissipated by the maximum fault resistance showed that increasing the pick-up setting by a factor of eight would have no detriment to safety. Therefore, either method would improve ground-fault relaying selectivity on high-voltage longwall mining systems, yet because of the escalating size of longwall systems, a directional relaying scheme is a longer term solution.","abstract_html":"The continuing trend toward larger longwall mining systems has resulted in the utilization of higher system voltages. The increase in system voltage levels has caused the industry to face complexities not experienced with the lower-voltage systems. One such complexity arises from the larger system capacitance that results from the outby configuration commonly used on 4,160-V longwall power systems. Simulations show that during a line-to-ground fault, the larger system capacitance can cause a situation where the ground current sensed by the ground-fault relays in unfaulted circuits is greater than the mandated ground-fault relay pick-up setting. Simulations show that ground-fault relaying selectivity is potentially lost as a result of this situation. Two alternatives were identified which could improve ground-fault relaying selectivity. They are: the application of a directional relaying scheme and increasing the ground-fault relay pick-up setting. It was determined that directional relays have an application to high-voltage longwall power systems as the ground current sensed by the relay in the unfaulted circuits is out of phase with the ground-fault current sensed by the relay in the faulted circuit. Furthermore, it was determined that raising the ground-fault relay pick-up setting by a factor of eight would also improve ground-fault relaying selectivity. A safety analysis considering the potential for electrocution and the power dissipated by the maximum fault resistance showed that increasing the pick-up setting by a factor of eight would have no detriment to safety. Therefore, either method would improve ground-fault relaying selectivity on high-voltage longwall mining systems, yet because of the escalating size of longwall systems, a directional relaying scheme is a longer term solution.","abstract_has_math":false,"creators":["Basar, Joseph James"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Mining and Minerals Engineering","degree_department":"Mining and Minerals Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Novak, Thomas"],"committee_members":["Reid, Gerald","Sottile, Joseph","Nieto, Antonio V.","Kohler, Jeffrey","Faria, Claudio"],"year":2004,"date_issued":"2004-04-23","date_published":"2004-04-23","updated_at":"2026-07-22T22:19:35Z","subjects":["coal mining","4160-V longwall","underground mining","mine power systems","coal electrical safety"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-04302004-010951"],"render_values":[{"text":"etd-04302004-010951","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/9888","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Novak, Thomas"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Reid, Gerald","Sottile, Joseph","Nieto, Antonio V.","Kohler, Jeffrey","Faria, Claudio"]},{"key":"dc:contributor.department","label":"Department","values":["Mining and Minerals Engineering"]},{"key":"dc:creator","label":"Author","values":["Basar, Joseph James"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2011-08-06T16:01:24Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2011-08-06T16:01:24Z","2004-05-05"]},{"key":"dc:date.issued","label":"Date","values":["2004-04-23"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mining and Minerals Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["coal mining","4160-V longwall","underground mining","mine power systems","coal electrical safety"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-04302004-010951"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/9888"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The continuing trend toward larger longwall mining systems has resulted in the utilization of higher system voltages. The increase in system voltage levels has caused the industry to face complexities not experienced with the lower-voltage systems. One such complexity arises from the larger system capacitance that results from the outby configuration commonly used on 4,160-V longwall power systems. Simulations show that during a line-to-ground fault, the larger system capacitance can cause a situation where the ground current sensed by the ground-fault relays in unfaulted circuits is greater than the mandated ground-fault relay pick-up setting. Simulations show that ground-fault relaying selectivity is potentially lost as a result of this situation. Two alternatives were identified which could improve ground-fault relaying selectivity. They are: the application of a directional relaying scheme and increasing the ground-fault relay pick-up setting. It was determined that directional relays have an application to high-voltage longwall power systems as the ground current sensed by the relay in the unfaulted circuits is out of phase with the ground-fault current sensed by the relay in the faulted circuit. Furthermore, it was determined that raising the ground-fault relay pick-up setting by a factor of eight would also improve ground-fault relaying selectivity. A safety analysis considering the potential for electrocution and the power dissipated by the maximum fault resistance showed that increasing the pick-up setting by a factor of eight would have no detriment to safety. Therefore, either method would improve ground-fault relaying selectivity on high-voltage longwall mining systems, yet because of the escalating size of longwall systems, a directional relaying scheme is a longer term solution."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Improvement of Ground-Fault Relaying Selectivity through the Application of Directional Relays to High-Voltage Longwall Mining Systems"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Novak, Thomas"],"dc:contributor.committeemember":["Reid, Gerald","Sottile, Joseph","Nieto, Antonio V.","Kohler, Jeffrey","Faria, Claudio"],"dc:contributor.department":["Mining and Minerals Engineering"],"dc:creator":["Basar, Joseph James"],"dc:date.accessioned":["2011-08-06T16:01:24Z"],"dc:date.available":["2011-08-06T16:01:24Z","2004-05-05"],"dc:date.issued":["2004-04-23"],"dc:description.abstract":["The continuing trend toward larger longwall mining systems has resulted in the utilization of higher system voltages. The increase in system voltage levels has caused the industry to face complexities not experienced with the lower-voltage systems. One such complexity arises from the larger system capacitance that results from the outby configuration commonly used on 4,160-V longwall power systems. Simulations show that during a line-to-ground fault, the larger system capacitance can cause a situation where the ground current sensed by the ground-fault relays in unfaulted circuits is greater than the mandated ground-fault relay pick-up setting. Simulations show that ground-fault relaying selectivity is potentially lost as a result of this situation. Two alternatives were identified which could improve ground-fault relaying selectivity. They are: the application of a directional relaying scheme and increasing the ground-fault relay pick-up setting. It was determined that directional relays have an application to high-voltage longwall power systems as the ground current sensed by the relay in the unfaulted circuits is out of phase with the ground-fault current sensed by the relay in the faulted circuit. Furthermore, it was determined that raising the ground-fault relay pick-up setting by a factor of eight would also improve ground-fault relaying selectivity. A safety analysis considering the potential for electrocution and the power dissipated by the maximum fault resistance showed that increasing the pick-up setting by a factor of eight would have no detriment to safety. Therefore, either method would improve ground-fault relaying selectivity on high-voltage longwall mining systems, yet because of the escalating size of longwall systems, a directional relaying scheme is a longer term solution."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:identifier.other":["etd-04302004-010951"],"dc:identifier.uri":["http://hdl.handle.net/10919/9888"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["coal mining","4160-V longwall","underground mining","mine power systems","coal electrical safety"],"dc:title":["Improvement of Ground-Fault Relaying Selectivity through the Application of Directional Relays to High-Voltage Longwall Mining Systems"],"dc:type":["Thesis"],"thesis:degree_discipline":["Mining and Minerals Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:35Z"}