The invention relates to locking and detaching mechanisms for plug-in units.
Plug-in units are generally used in electrical engineering. A plug-in unit assembly comprises a case and a plug-in unit arranged to be attached thereto. The plug-in unit comprises electrical components and related connectors arranged to be coupled to corresponding mating connectors installed in the case when the plug-in unit is being attached to its case. The electrical components installed in the plug-in unit may be instrument transformers, for example.
In plug-in unit assemblies, it is known to use locking means arranged to lock the plug-in unit immovably to the case.
In known plug-in unit assemblies, detaching the plug-in unit from the case is difficult because of the high contact forces between the connectors of the plug-in unit and the mating connectors of the case. Previously, attempts were made to solve this problem by installing a handle in the plug-in unit for facilitating the withdrawal, the handle also serving as a part of the locking means of the plug-in unit. The problem in this arrangement is that when the plug-in unit is inserted into the case, said handle has to be kept in an unlocking position, i.e. in a position enabling the withdrawal of the plug-in unit from the case. In a plug-in unit, such a handle complicates the installation of the plug-in unit into the case.