§ 690-336. Longwall electrical protection
Purdon's Pennsylvania Statutes and Consolidated StatutesTitle 52 P.S. Mines and MiningEffective: January 5, 2009
Effective: January 5, 2009
52 P.S. § 690-336
§ 690-336. Longwall electrical protection
(2) Time-delay settings of short-circuit protective devices used to protect any cable extending from the section power center to a motor-starter enclosure must not exceed the settings specified in approval documentation or one-quarter second, whichever is less. Time-delay settings of short-circuit protective devices used to protect motor and shearer circuits must not exceed the settings specified in approval documentation or three cycles, whichever is less.
(iii) Thermal protection for the grounding resistor that will de-energize the longwall power center if the resistor is subjected to a sustained ground fault. The thermal protection must operate at either 50% of the maximum temperature rise of the grounding resistor or 150 Centigrade or 302 Fahrenheit, whichever is less, and must open the ground-wire monitor circuit for the high-voltage circuit supplying the section power center. The thermal protection must not be dependent upon control power and may consist of a current transformer and overcurrent relay.
(b) Current transformers.--Current transformers used for the ground-fault protection specified in subsection (a)(1), (4)(i) and (5) must be single window type and must be installed to encircle all three-phase conductors. Equipment safety grounding conductors must not pass through or be connected in series with ground-fault current transformers.
(c) Test circuit.--Each ground-fault current device specified in subsection (a)(4)(i) and (5) must be provided with a test circuit that will inject a primary current of 50% or less of the current rating of the grounding resistor through the current transformer and cause each corresponding circuit-interrupting device to open.
(e) Multiple cables.--Where two or more high-voltage cables are used to supply power to a common bus in a high-voltage enclosure, each cable must be provided with ground wire monitoring. The ground wire monitoring circuits must cause de-energization of each cable when either the ground monitor or grounding conductor of any cable becomes severed or open. On or after the effective date of this section, parallel-connected cables on newly installed longwalls must be protected as follows:
(2) when two or more parallel circuit-interrupting devices are used to protect parallel-connected cables, the circuit-interrupting devices must be mechanically and electrically interlocked. Mechanical interlocking shall cause all devices to open simultaneously and electrical interlocking shall cause all devices to open when any cable is disconnected.
Credits
2008, July 7, P.L. 654, No. 55, § 336, effective in 180 days [Jan. 5, 2009].
52 P.S. § 690-336, PA ST 52 P.S. § 690-336
Current through Act 13 of the 2024 Regular Session. Some statute sections may be more current, see credits for details.
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