Abstract: Methods and devices for an extreme duty transformer with wet wound primary and secondary winding encapsulated with a resin and having corrugated insulating material as cooling ducts as a transformer capable of withstanding extreme mechanical stresses in an underground mining environment. The method includes providing a resin impregnated rectangular winding form, forming a secondary winding with alternating layers of magnet wire with a resin impregnated insulating collar above and below the magnet wire and corrugated insulating material extending the full or partial circumference and width of the coil. An insulating layer of corrugated material and resin impregnated insulation is wound to separate the primary from the secondary windings.

Abstract: A vacuum load break switch uses a vacuum interrupter for the load break device together with a series connected visible disconnect which is interlocked with the vacuum interrupter mechanism. Further, the visible disconnect is grounded in the fully opened switch position. A manual switch operator is provided together with interconnect means interconnecting the manual switch operator to both the visible disconnect switch means and the vacuum interrupter in a manner such that in a switch closing operation of the manual switch operator the visible disconnect switch means closes before the vacuum interrupter means and in an opening operation the vacuum interrupter means opens before the visible disconnect switch means. Additionally, an additional solenoid operated switch operator is coupled to the interconnect means for opening the vacuum interrupter through solenoid action.

Abstract: An electrical plug and receptacle assembly in which the number of different parts is minimized, is characterized by the use of an identical insulator in both the plug housing and the receptacle housing. The insulator has contact compartments adapted to mount either male or female contacts. Both the male and female contacts include an integral cable terminal. Additionally, the female contacts are segmented and include spring means for biasing the female contacts into tight engagement with male contacts. A cable clamp is also provided with the plug assembly which can effectively clamp either round or flat cables.