Abstract
With the advent of high-voltage (greater than 1 kV) utilization circuits on longwall mining equipment in the late 1980's, the Mine Safety and Health Administration (MSHA) initially required maximum ground-fault current limits of 3.75 A for 4160-V systems and 6.5 A for 2400-V systems. Ground-fault relay pickup settings were not permitted to exceed 40% of the maximum ground-fault current. Shortly thereafter MSHA began, and presently continues, requiring a much lower maximum ground-fault current limit of 1.0 A, or even 0.5 A, with ground-trip settings of 100 mA. Shielded cables, which have significantly more capacitance than their unshielded counterparts, are required for high-voltage applications in the mining industry. In an earlier paper, the author showed that with the long cable runs of a high-voltage longwall system, capacitive charging currents could easily exceed grounding-resistor currents under ground-fault conditions. As a result, overvoltages from inductive-capacitive resonance effects can occur. Because of the large system capacitance and low ground-trip setting, the relay selectivity of the ground-fault protection system may also be compromised. Therefore, an analysis of a typical 4160-V longwall power system that utilizes very-high resistance grounding (ground-resistor-current limit of 0.5 A) is performed to determine of potential problems exist with the selectivity of ground-fault relaying.
| Original language | English |
|---|---|
| Pages (from-to) | 212-221 |
| Number of pages | 10 |
| Journal | Conference Record - IAS Annual Meeting (IEEE Industry Applications Society) |
| Volume | 1 |
| State | Published - 1999 |
| Event | Proceedings of the 1999 IEEE Industry Applications Conference - 34th IAS Annual Meeting - Phoenix, AZ, USA Duration: Oct 3 1999 → Oct 7 1999 |
ASJC Scopus subject areas
- Control and Systems Engineering
- Industrial and Manufacturing Engineering
- Electrical and Electronic Engineering