This invention relates to an electromagnetic switchgear in general and more particularly to such switchgear which provides for closing of the magnet when break contacts are welded.
Electromagnetic switchgear with movable contact parts held in a movable contact support and forming, with fixed contact parts, opening and closing contacts is known, for example, from U.S. Pat. No. 4,737,749. In the disclosed switchgear the contact support is elastically connected with the armature in such a way that, if the opening contacts become welded together, an onward movement of the movable magnet part is possible without actuation of the closing contacts. Upon the welding of opening contacts the closing contacts are thus prevented from closing. In such a case to cause the magnet system to close, i.e., to be magnetically closed, in order to prevent the coil from blowing, a relatively large spring excursion of the coupling spring between the contact bridge support and the armature is required. This has an adverse effect on the size of the switchgear. Thus, there is a need for a switchgear of the above-mentioned kind which is easy to construct while being compact.
USPTO Backgrounds
USPTO Backgrounds