Automation Parts

The typical fuse consists of an element which is surrounded by a filler and enclosed by the fuse body. The element is welded or soldered to the fuse contacts (blades or ferrules). The element is a calibrated conductor. Its configuration, its mass, and the materials employed are selected to achieve the desired electrical and thermal characteristics. The element provides the current path through the fuse. It generates heat at a rate that is dependent upon its resistance and the load current. Mersen (Gould Ferraz Shawmut) Fuse Construction The heat generated by the element is absorbed by the filler and passed through the fuse body to the surrounding air. A filler such as quartz sand provides effective heat transfer and allows for the small element cross-section typical in modern fuses. The effective heat transfer allows the fuse to carry harmless overloads. The small element cross section melts quickly under short circuit conditions. The filler also aids fuse performance by abs...

Renold Couplings Highlights Folly Of Fuse Theory Fuse theory, a myth related to couplings, is costing industry a fortune, according to Paul Shuffleton, managing director of Renold Hi-Tec Couplings. According to fuse theory, rubber-in-shear type flexible couplings protect diesel-driven generator sets by failing or acting like a fuse when there is a potentially damaging short circuit. This is a myth, because the majority of rubber-in-shear couplings fail through fatigue rather than because of a short circuit. This is also the main reason for failing rubber blocks. Rubber-in-shear couplings consist of a rubber element fused in-between two metal hubs. One hub drives the other through the rubber, the flexing of which protects against shock and vibration. The coupling is only as strong as the rubber element, so if the rubber fails then the coupling fails too. When this happens on a diesel-driven generator set, some engineers believe there has been a short circuit and that the relatively ...