Types of Fuses

Types of Fuses Points : Types of Fuses, Rewire able fuse, H.R.C fuse. cartridge fuse There are following types of fuses:
(a) Rewire able fuse
(b) H.R.C fuse
(c) Cartridge fuse (a) Rewire able fuse The simplest type of fuse in general use is the rewire able fuse. It has two parts, a base and carrier. The carrier is manufactured by a moulded plastic. The incoming and outing cables are connected with base contacts. The carrier has two contacts and the fuse link is connected between these two contacts, when fuse link is break due to faulty current then we pulled out the carrier, the blown wire replaced and, new wire can placed and then again put the carrier into base and the service of supply continue. Such fuse has limited .application in industry. It is commonly used in domestic wiring.

(b) H.R.C Fuses If we use H.R.C fuse in the circuit, the short circuit current is limited to a value corresponding to cut-off. The fuse link is a unit in which the fuse element ii enclosed; When fuse element is blown we replace it. The outer body of H.R.C fuse is usually made of ceramic material. Now a days epoxy resins have been used and replacing the ceramic material.

The fuse element is always fitted inside the body. The ends of the fuse element re-connected to the metal end caps. In H.R.C fuse element an indicator pin is provided, which .indicates, when the fuse is blows out. HR.C fuses are available in ampere rating from 2 to 300A.

When faulty current passing through the fuse element produces heat, as a result due to this heat fuse element is blown out.

(c) Catridge Fuse Two types of catridge fuses are mostly used in the industry. One is a ferrule type that makes contact through round copper rings at each end’ of the catridge. The catridge is inserted into clips (fuse holders) and the copper rings bridge the line to the load. The other is knife-blade type. Copper blades are fitted into clips and bridge the line to the load. The catridge fuses are available in ampere ratings from 1/10 to 600A and in voltage ratings off, 125,250,300 and 600 volts. Catridge fuse consists of a tube with two end caps.

The fuse element is connected between these two end caps. The body of a fuse is made by porcelain or steatite. The end caps of fuse are normally made by tinned brass or copper. The end caps are rigidly attached to the body of fuse so that they do not blow of, when the faulty current flows through it only fuse element is blown out. The fuse element is in the form of a wire or thin strips. The catridges of fuse are usually filled with quartz sand. The advantage of filling the catridge with sand is that when high current flows through it a are is produced. The characteristic of sand is that, it absorbs and exunguishes the are.