Equipment and Apparatus Circuit Protection

In an imperfect world reliable protection of equipment and apparatus from damage due to an electrical overload or because of a malfunction in the equipment is an absolute necessity. A choice of protective devices is available: fuses, thermal protectors, thermal-magnetic circuit breakers, magnetic circuit breakers. Each of these devices has its place and serves a useful function. They all have some common features, yet they are far from being functionally interchangeable, and a misapplication can have expensive consequences. Advantages and disadvantages of a protective device have to be carefully evaluated to insure effective circuit protection at the most reasonable cost. Circuit protective devices are available in a wide range of ratings and with a multitude of features. Care must be exercised when a protective device is specified so that its characteristics and its special features are fully compatible with the equipment it has to protect. Special DC circuit breakers for the telecommunications industry have been developed in recent years. They provide reliable protection for power equipment at moderate cost.