METHOD AND APPARATUS FOR PERFORMING ON-LOAD MECHANICAL SWITCHING OPERATIONS

摘要

An electrical device comprising: a first current path having a primary switch therein, and means for coupling to an electrical supply; and a diversionary current path having semiconductor switching means therein, the semiconductor switching means being operable to bypass the primary switch; the device being arranged such that, in use, a first current flowing from the supply along the first current path can be diverted, on the operation of the semiconductor switching means, along the diversionary current path, bypassing the primary switch; wherein the diversionary current path comprises a controllable electrical supply operable to supply a second current whilst the semiconductor switching means are in a state of conduction, the second current being such as to cause substantially zero current to flow through the primary switch, such that the primary switch can then be opened under a condition of substantially zero load current. A corresponding method of operating a mechanical switch in such a device is also provided. The disclosure further provides a controllable electrical supply comprising: an electrical source; an amplifier having two output terminals and comprising a plurality of semiconductor devices; and control logic arranged to operate the amplifier such that it can selectively present both current and voltage source behaviour at the terminals.