Switching appts. for electric plant in mining - uses current transformers with output connected to comparison transformer delivering shut=down pulse on electric fault occurrence

摘要

Mining and tunnelling electric plant switch-off appts. is used in conjunction with electric drive(s) housed in pressure-tight casing(s) to protect the ambient from sparking effects occurring in the drive(s), and is brough into action when an electrical fault occurs in the drive(s). The appts. rapidly switches off the electrical plant, when faults, such as short-circuit arcing, leakage currents in the insulation, or distruptive arcing across to the drive(s) housing etc. occur, by rapidly shutting off the drive current. Thus current transformers are associated with the input and output leads of the drive(s) and their output is connected to a comparator transformer that delivers an impulse when compliance between the input and output of the drive(s) is lacking, the impulse serving as the shutdown pulse for the plant.