Improvement of Ground-Fault Relaying Selectivity through the Application of Directional Relays to High-Voltage Longwall Mining Systems
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 c...
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ndltd-VTETD-oai-vtechworks.lib.vt.edu-10919-98882020-09-29T05:43:45Z Improvement of Ground-Fault Relaying Selectivity through the Application of Directional Relays to High-Voltage Longwall Mining Systems Basar, Joseph James Mining and Minerals Engineering Novak, Thomas Reid, Gerald Sottile, Joseph Nieto, Antonio V. Kohler, Jeffrey Faria, Claudio coal mining 4160-V longwall underground mining mine power systems coal electrical safety 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. Master of Science 2011-08-06T16:01:24Z 2011-08-06T16:01:24Z 2004-04-23 2004-04-30 2004-05-05 2004-05-05 Thesis etd-04302004-010951 http://hdl.handle.net/10919/9888 http://scholar.lib.vt.edu/theses/available/etd-04302004-010951 Thesis.pdf In Copyright http://rightsstatements.org/vocab/InC/1.0/ ETD application/pdf Virginia Tech |
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coal mining 4160-V longwall underground mining mine power systems coal electrical safety |
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coal mining 4160-V longwall underground mining mine power systems coal electrical safety Basar, Joseph James Improvement of Ground-Fault Relaying Selectivity through the Application of Directional Relays to High-Voltage Longwall Mining Systems |
description |
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. === Master of Science |
author2 |
Mining and Minerals Engineering |
author_facet |
Mining and Minerals Engineering Basar, Joseph James |
author |
Basar, Joseph James |
author_sort |
Basar, Joseph James |
title |
Improvement of Ground-Fault Relaying Selectivity through the Application of Directional Relays to High-Voltage Longwall Mining Systems |
title_short |
Improvement of Ground-Fault Relaying Selectivity through the Application of Directional Relays to High-Voltage Longwall Mining Systems |
title_full |
Improvement of Ground-Fault Relaying Selectivity through the Application of Directional Relays to High-Voltage Longwall Mining Systems |
title_fullStr |
Improvement of Ground-Fault Relaying Selectivity through the Application of Directional Relays to High-Voltage Longwall Mining Systems |
title_full_unstemmed |
Improvement of Ground-Fault Relaying Selectivity through the Application of Directional Relays to High-Voltage Longwall Mining Systems |
title_sort |
improvement of ground-fault relaying selectivity through the application of directional relays to high-voltage longwall mining systems |
publisher |
Virginia Tech |
publishDate |
2011 |
url |
http://hdl.handle.net/10919/9888 http://scholar.lib.vt.edu/theses/available/etd-04302004-010951 |
work_keys_str_mv |
AT basarjosephjames improvementofgroundfaultrelayingselectivitythroughtheapplicationofdirectionalrelaystohighvoltagelongwallminingsystems |
_version_ |
1719345956083728384 |