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AssigneeDBT GmbH
InventorsJens Titschert, Markus Lenzing, Jeff Travis, Dan Ferguson
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The present invention relates to a protection circuit for intrinsically safe electromagnetic actuators operating on the voltage from a power unit (1) approved for underground mining, for switching electrohydraulic valves (5) in underground mining, comprising at least two spaced-apart short-circuit means (14, 16 or 16A) connected in parallel with the electromagnetic actuator coil (11) for short-circuiting the coil in the event of a reversal of the coil voltage. According to the invention, at least one of the short-circuit means comprises a short-circuit semi-conductor switch (16 or 16A) and a voltage-reversal detecting circuit (30) for activating the short-circuit semiconductor switch (16).
A protection circuit for intrinsically safe electromagnetic actuators operating on the voltage from a power unit approved for underground mining, for switching electrohydraulic valves in underground mining, comprising at least two spaced-apart short-circuit means connected in parallel with the electromagnetic actuator coil for short-circuiting the coil in the event of a reversal of the coil voltage, in which at least one of the short-circuit means comprises a short-circuit semi-conductor switch and a voltage-reversal detecting circuit for activating the short-circuit semiconductor switch.
A protection circuit for intrinsically safe underground energy supply systems comprising a number of electronic control units connected to a common power supply approved for underground mining, for activating respective electromagnetic actuators connected to the control units and operated by the power-supply voltage for switching electrohydraulic valves in underground mining, wherein each electromagnetic actuator is associated with at least one short-circuit means connected in parallel with the coil of the electromagnet for short-circuiting the coil in the event of a reversal of the coil voltage, in which the protection circuit comprises at least one short-circuit means with a short-circuit semiconductor switch and a voltage-reversal detecting circuit for activating the short-circuit semiconductor switch.
Dependencies are inferred from the claim text.