What Are Fuses?

A fuse is a narrow wire, which either melts or vaporizes when much current flows through it. The narrow wire may be made of aluminum, tin-coated copper or nickel. The resulting open in the circuit stops current flow. In electronic equipment, most fuses are cylindrical glass or ceramic type with a metal cap at each finish! The current rating may even be seen in of the metal finish caps. There are popular physical sizes: 1 - ¼ X ¼ - inch & 5X20mm. The 1 - ¼ X ¼ - inch size is used in lots of automobiles. You'll find both sizes in lots of electronic equipment, but the smaller X 20mm has become more common. Fuses are available with current ratings from 1/500 Ampere to hundreds of amperes.

Purpose of Fuses

The purpose of a fuse is to open an electronic circuit when current flow exceeds a positive amount, determined by the rating of the fuse. Opening a circuit under high current conditions can save electronic parts from damaged & prevents overheating, which could cause a fire.

Types of Fuses

There are basic types of fuses: fast acting & slow blow. The fast acting type will open quickly when their particular current rating is exceeded. This is important for analog meter movements, which can quickly be destroyed when much current flows through them, for even a tiny amount of time. Slow blow fuse have a coiled construction inside. They are designed to open only on a continued overload, such as a short circuit. The purpose of coiled construction is to prevent the fuse from blowing on a temporary current surge.

Do not use a slow blow fuse than a fast acting fuse. It may not open fast to prevent parts destroy under a high current condition. It is not harmful to replace a slow blow fuse with a fast-acting fuse, but it will probably open up unnecessarily every now & then when the equipment is first switch on. A blown fuse can tell you something about your service issue. Often the glass case of the fuse appears clear, & you can still see the broken pieces of the fuse element. This means you have the kind of issue that causes a slow, gradual overload on the power supply. Some fuses even die of elderly age. But if the inside of the glass fuse is discolored, & there is no trace of the fuse element (the middle connector), you know that the middle connector was destroyed quickly & violently, using lots of heat. The fault was a short circuit or other issue that caused lots of current to flow quickly.

Are some cases a fuse will open up fast when there is a surge so that other parts are not damaged. If this is the case, replacing the fuse with of the same type & rating restores operation. Regrettably, a high probability exists that if a fuse blew, something in the circuit it was defending shorted out. In this case, a replacement fuse blows right away. The blown fuse can fundamentally get replaced by a new, after the overload has been eliminated when come in to replacement. Use only the same current & voltage ratings as the original. The common type & current rating of a fuse in a monitor is slow blow 2A to 5A. When you buy replacement fuses, get several - you can fundamentally use all of them while you are troubleshooting an elusive issue.