protective device for encapsulated in insulating material and by means of the device foremal protected electrical apparatus with kapslad magnetkerna

摘要

The present invention relates to a device for protecting inserts against stress arising from resin shrinkage during embedding. The device is characterised in that an insert 1 e.g. comprised of helically wound magnetic plates or a stack of rings is protected by an envelope constituted by an annular shell 6 having a surface transverse to the main forces 11, 13 which may be exerted as a result of the coating material 9 contracting after moulding, a layer of resilient material 7 interposed between the shell 6 and the insert 1, and a cover 8 surrounding the assembly of the insert 1, the resilient layer 7 and the shell 6. The cover 8 prevents the moulded insulating resin material 9 from reaching the assembly. The insert 1 may be annular as shown, or rectangular (Figs. 6-8 not shown). The shell 6 may be of metal and may be provided with clips (10 Fig. 4 not shown) for positioning it in the mould. The cover 8 may comprise a wound strip of electrically insulating material. The invention may be applied particularly to the protection of instrument transformers. IMAGE