Best Practices for Implementing High-Resistance Grounding in Mine Power Systems

Sottile, J.; Tripathi, Anjana; Novak, Thomas

doi:10.1109/tia.2015.2420632

Cited by 11 publications

(5 citation statements)

References 7 publications

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“…The mining industry has been faced with a much higher system charging current [10]. With the application of new protection devices, clearing line-to-ground fault in <10 cycles in a HRG system with very high system charging current and no directly connected motors at MV should not pose a danger of faults involving other phases into the fault that has been described in [3].…”

Section: Medium-voltage Hrg System Protection and Discussion Of mentioning

confidence: 99%

“…It appears that an HRG design has been-and continues to be-applied to MV systems with a system-charging current much higher than 5.5 A, and voltage much higher than 4.16 kV, where protection devices automatically isolate the faulted section upon sensing a first line-ground fault [10]. For high system-charging currents and for higher MV systems, a ground-fault protection scheme with highaccuracy current transformers (CTs) should be applied to trip the power system within 7 to 10 cycles.…”

Section: Background Historymentioning

confidence: 99%

“…The Mining Electrical Safety Health Administration (MESHA) has a safety criterion that requires limiting the ground-fault current to a low magnitude. Long MV underground feeder cables contribute to a very high system charging current of 68 A, where the HRG neutral grounding resistor current rating may be as high as 68 A [10]. This HRG power system will result in a bolted line-to-ground fault current of 100 A; which is the current definition of the LRG power system [1].…”

Section: Mining Industry Use Both LV and Mvmentioning

confidence: 99%

“…Tripping the MV system requires very sensitive ground-fault protection relays and associated high-accuracy CTs. The discussion of sensitive motor ground fault current protection with pick setting of 100 ma in the mining industry are beyond the scope of this paper [10]. Unique ground fault pro te c tio n s c he me s o f V F D driv e s in t he H R G sy s te ms , which require specific discussion is also not included in this paper [26] [27].…”

Section: Mining Industry Use Both LV and Mvmentioning

confidence: 99%

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High-Resistance Grounded Power System

Paul¹

2015

IEEE Trans. on Ind. Applicat.

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To minimize ground fault during a line-to-ground fault condition, it has been a common practice to use highresistance grounded (HRG) power systems, both at low voltage (LV) and at medium voltage (MV). The criteria for designing HRG systems are very well known to the industry; however, the opinions of industry experts have been divided on limiting the use of HRG systems for MV systems to voltages of less than 4.16 kV and phase-ground fault currents of less than 10 A without clarifying that it applies to systems which require continuous operation upon detecting first line-to-ground fault as it is now in reference [1]. This paper will review the background history of HRG power systems and their application to MV systems for specific industries and will make the case that voltages need not be limited to less than 4.16 kV and phase-ground fault current less than 10A, so long as the faulted power system is isolated within 10 cycles and there are no direct connected motors. This paper will discuss the potential damage and protection requirements of HRG systems for MV applications to ensure that a line-to-ground fault is cleared before it involves other phases to make a multiphase arcing ground fault.Index Terms-Arcing fault, fault resistance, ground fault protection relay, high-resistance grounded system, system charging current. 0093-9994 (c)

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Section: Medium-voltage Hrg System Protection and Discussion Of mentioning

confidence: 99%

Section: Background Historymentioning

confidence: 99%

Section: Mining Industry Use Both LV and Mvmentioning

confidence: 99%

Section: Mining Industry Use Both LV and Mvmentioning

confidence: 99%

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High-Resistance Grounded Power System

Paul¹

2015

IEEE Trans. on Ind. Applicat.

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“…There is limited test data [4], [5] and less research data to fully understand the 10-A limitation; however, the author believes that an HRG system can be applied to an MV system with a system-charging current much higher than 5.5 A and voltage much higher than 4.16 kV, provided the design includes power system tripping within 10 cycles upon sensing a line-ground fault. Reference paper [7] cites an HRG with 25 A and [8] cites an HRG with 69 A. For MV systems with high system-charging current, a very sensitive neutral ground fault relay [device (50/51 G)] with a high-accuracy current transformer (CT) or device 59 G that should be applied to trip the power system within 10 cycles or less is recommended.…”

mentioning

confidence: 99%

High-Resistance Grounded Power-System Equivalent Circuit Damage at the Line–Ground Fault Location—Part I

Paul¹

2014

IEEE Trans. on Ind. Applicat.

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This paper provides an electrical equivalent circuit of a high-resistance grounded (HRG) power supply transformer to discuss damage at a fault location so long as the fault remains a line-ground fault. Fault resistance and fault current that have an effect on damage are included in the equivalent circuit. Three-line diagrams showing fault current flows along with their vector diagrams are also included. Part II of this paper provides a similar equivalent circuit for an HRG grounded generator. This paper provides guidance to update the current edition of IEEE STD. 142 with respect to HRG systems.

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