AC/DC power supply

Electro lifting magnets have to be energized by direct current. For safe operation of existing or new lifting magnets, special type power supply units or DC-controllers are necessary. Design of our typical power supply station consists out of a disconnecting transformer for galvanic mains separation and adjustment of voltage, one or several AC type mains contactors for switching of transformers secondary voltage, one controlled or uncontrolled type rectifier and DC type contactors for switching of the magnet current. In addition bigger size units will be equipped with a suppressor circuit for limitation of inductive voltage and to relieve the energy of the magnet coil. By standard all functions will be PLC controlled, for simple application or upon customers request, controller can be supplied without PLC at all as well off course. Each magnet equipment being operated in an unprotected area (according to European standard DIN-EN 13155), such as steel trading, (un)loading of trucks, (un)loading of bundles, billets or slabs in a steel mill and so on, where personnel could remain within the danger area during magnet application, has to be equipped with an emergency power supply station with back-up batteries, to prevent an accidental drop of load, caused by mains power failure. A typical back-up time is about 20 minutes, according to regulation 10 minutes are minimum. If evacuation of danger area is difficult, e.g. when (un)loading of vessels, power supply station as well as cabling of crane and coils of magnets, have to be carried out in redundant version.