The wiring in the coil will be coated with electrically insulating varnish. The coil will burn if the insullation of this varnish breaks down. This will happen because of moisture, salt corrosion or physical damage. Also a short circuit in the load causing too much current will overheat the coil and melt the varnish. If the coil is meant to attract a former towards it, as in a contactor, then if the moving former gets jammed, the coil will burn out. |