The fault current is interrupted inside the fuse-link body and although this is very fast, there is no sign of it outside. The main elements in these fuses are: a barrel of class F insulating synthetic material, nickel plated aluminium end contacts, pure silver fuse elements and a composite material fuse element holder to withstand high temperatures. Thanks to their structure, based on a synthetic material, FR fuse-links are the perfect answer to the stress involved in use inside HV bays and fuse-link chambers.