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).