Section 690-342 - High-voltage longwall mining systems(a) General rule.--In each high-voltage motor-starter enclosure, with the exception of a controller on a high-voltage shearer, the disconnect device compartment, control/communications compartment and motor contactor compartment shall be separated by barriers or partitions to prevent exposure of personnel to energized high-voltage conductors or parts. Barriers or partitions shall be constructed of grounded metal or nonconductive insulating board.(a.1) High-voltage shearers.--In each motor-starter enclosure on a high-voltage shearer, the high-voltage components shall be separated from lower voltage components by barriers or partitions to prevent exposure of personnel to energized high-voltage conductors or parts. Barriers or partitions shall be constructed of grounded metal or nonconductive insulating board.(b) Interlock switches.--Each cover of a compartment in the high-voltage motor-starter enclosure containing high-voltage components shall be equipped with at least two interlock switches arranged to automatically de-energize the high-voltage components within that compartment when the cover is removed.(c) Circuit-interrupting devices.--Circuit-interrupting devices shall be designed and installed to prevent automatic reclosure.(d) Transformers.--Transformers with high-voltage primary windings that supply control voltages shall incorporate grounded electrostatic (Faraday) shielding between the primary and secondary windings. The shielding shall be connected to the equipment ground by a minimum No. 12 AWG grounding conductor. The secondary nominal voltage shall not exceed 120 volts, line to line.(e) Test circuits.--Test circuits shall be provided for checking the condition of ground wire monitors and ground-fault protection without exposing personnel to energized circuits. Each ground-test circuit shall 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.(f) Disconnect devices.--Each motor-starter enclosure, with the exception of a controller on a high-voltage shearer, shall be equipped with a disconnect device installed to de-energize all high-voltage power conductors extending from the enclosure when the device is in the open position. (1) When multiple disconnect devices located in the same enclosure are used to satisfy the requirement of this subsection, they shall be mechanically connected to provide simultaneous operation by one handle.(2) The disconnect device shall be rated for the maximum phase-to-phase voltage and the full-load current of the circuit in which it is located and installed so that: (i) visual observation determines that the contacts are open without removing any cover;(ii) the load-side power conductors are grounded when the device is in the open position;(iii) the device can be locked in the open position;(iv) when located in an explosion-proof enclosure, the device shall be designed and installed to cause the current to be interrupted automatically prior to the opening of the contacts; and(v) when located in a nonexplosion-proof enclosure, the device shall be designed and installed to cause the current to be interrupted automatically prior to the opening of the contacts, or the device shall be capable of interrupting the full-load current of the circuit.(g) Starters to be interlocked.--Control circuits for the high-voltage motor starters shall be interlocked with the disconnect device so that: (1) The control circuit can be operated with an auxiliary switch in the test position only when the disconnect device is in the open and grounded position.(2) The control circuit can be operated with the auxiliary switch in the normal position only when the disconnect switch is in the closed position.(h) Determination of minimum available fault current.--A study to determine the minimum available fault current shall be submitted to the department to ensure adequate protection for the length and conductor size of the longwall motor, shearer and trailing cables.(i) Shielded construction of certain cables.--Longwall motor and shearer cables with nominal voltages greater than 660 volts shall be made of a shielded construction with a grounded metallic shield around each power conductor.(j) Instantaneous ground fault protection.--High-voltage motor and shearer circuits shall be provided with instantaneous ground fault protection of not more than 0.125 of an ampere. Current transformers used for this protection shall be of the single window type and shall be installed to encircle all three-phase conductors.2008, July 7, P.L. 654, No. 55, §342, effective in 180 days [ 1/5/2009].