Electromagnetic coupling for machine tool with rapid excitation - has capacitor in series with coil and thyristor and diode shunt linked to auxiliary low power voltage

摘要

An electromagnetic coupling for a machine tool has a circuit to produce rapid excitation. The excitation current is supplied to several electromagnets in the machine tool. The additional power loss is very small. The circuit contains a mechanical or electronic switch and a dropper resistor. There is a capacitor (4) connected in series with a coil of the electromagnet (2) and the thyristor. The capacitor is shunted by a diode (5) to conduct in the direction of flow of the load current. The diode is linked to an auxiliary low power voltage via a resistor (7).