Power relays are designed to withstand the current of the electrical circuit into they are inserted and to cut off the electrical circuit under load. Power relays are usually constructed in that the electromagnet with yoke, the contact system, and the arc extinguishing equipment, are built separately, and the relay as a whole is subsequently assembled from such subassemblies. A power relay may include a slide for operating a contact spring. The slide has an end edge lying parallel to the surface of the contact spring that contacts and pushes against the broad side of a contact spring for actuating the middle contact spring. Electromechanical relays comprise one or more electrical contacts having a mechanical movement, these being coupled to a moveable element of the magnetic circuit of an electromagnet. The development and ready availability of various solid state electronic devices has replaced the old reliable electromagnetic relay for controlling the flow of AC power while affording electrical isolation between the switching path and the actuating control elements.