Abstract: The invention proposes a switchgear for generating a clock-controlled coil current that flows through a magnet coil arrangement (10), wherein said switchgear contains change-over means (16) for changing over from an initially higher pickup current to a lower retaining or operating current after a predetermined pickup time. A frequency detection stage (18) serves for monitoring the current control signal (Upwm) for the magnet coil arrangement and for changing over to the higher pickup current or the higher voltage causing the higher pickup current if the frequency signal fails to appear. This not only makes it possible to reliably detect an undercurrent with simple means, but also to initiate measures for the continued safe operation of the magnet coil arrangement (10).