Abstract: Power supply circuit for a single-winding electromagnet coil (11) comprising a low voltage DC power supply (20) and a high voltage AC power supply (30) both connected to the terminals of the winding (11), together with a switching apparatus (40) connected in series with the high voltage supply (30) and capable of supplying or cutting the high voltage power supply to the winding (11), characterized by the fact that the switching device (40) comprises a thyristor (42) connected between the high voltage source (30) and the winding (11) and a control circuit (43) for the thyristor (42) connected to the gate (G) of the thyristor used to cause the thyristor to conduct when the high voltage source (30) delivers the positive phase of a voltage wave.

Abstract: An electrical device for switching an arc to a path parallel to a device to be protected. The electrical device includes double breaking contacts and an arc transfer electrode associated with the parallel path. The parallel path shunts the double breaking contacts and a device to be protected via the arc transfer electrode. The arc transfer electrode is placed in the vicinity of a fixed contact of the double breaking contacts.

Abstract: A switch device using a main switch coupled to a monostable auxiliary switch through a releasable coupling is disclosed. In this device, the auxiliary switch and the main switch are closed in succession by simultaneous movement of their respective contact-holders and are opened in the reverse order by virtue of the presence of the releasable coupling which is released during closing and engaged during opening.