Resistors in Electronics

The resistors size is dependent on the need. They are available in sizes ranging from 0.01 Ohms to 10 Megaohms. However, there is a lot of flexibility in sizes that are commercially available. The external sealing material is equipped with color coded bands that designate the rating when viewed in a specific sequence. There are four band, five band, and six band color coded options. Each color band represents a numerical value, a resistance multiplier (in Ohms), and a percentage tolerance.

Current shunt resistors are not designed to be used at their full capacity continuously. “Continuously” is defined as being more than 2 minutes of use. Doing so could overheat and damage the resistors which would give inaccurate measurements. If a shunt resistor becomes too hot for too long will be permanently damaged. Most shunt resistors have a “derating factor” of 66%. This means that you would not operate the 100Amp shunt resistor in our example at more than 66 Amps.

Pulse resustors are specifically used in a circuit to literally "withstand" the excess load and heating that accompanies a transient energy event. Hence, they are typically known as Power Withstanding Resistors (PWRs). Fusing with flameproof protection, under specific fault conditions, can also be designed into the resistor performance where necessary. The types of resistor technologies available are wirewound, metal film, metal oxide, and surface mount. Telecommunications, computers, consumer electronics, and office equipment are just a few of the applications in which a pulse resistor may be used.

So whether designer, troubleshooter, or electronics hobbyist, having a basic understanding of how a resistor is used in the design of electronic and electrical equipment, can only serve to meet the objectives of the application and bring about a greater appreciation for electronic technology.