Mayr Transmission's new ROBA-multiswitch, for the rapid switching of safety brakes, sustains a constantly controlled dc voltage independent of the mains voltage. This means that adapting magnetic coils to varying input voltages becomes unnecessary. Over-excitation on switch-on ensures that the connected brakes release extremely quickly. Two designs are sufficient to cover all mains voltages worldwide, from 100 to 250 VAC or 200 to 500 VAC, and mains frequencies of 50 to 60 Hz.
In order to achieve the quickest release possible, brakes are often switched on with over-excitation; meaning they are supplied with a voltage which is much higher than the coil nominal voltage. This function, too, is integrated in the new ROBA-multiswitch. When switched on, the device temporarily (0 to 50 ms) produces a bridge voltage, equivalent to 90% of the applied mains voltage, which is rectified and applied to the magnetic coil. After this very short phase, a controlled over-excitation voltage of 180 Vdc is applied. The over-excitation time is selected via DIP switch.