dropout fuse cutout and surge arrester

Fuse Cutout

1.Fuse Cutout, also called Dropout fuse, is an electrical device that disconnects a circuit by causing the fuses to melt with its own heat when the current exceeds a specified value. A fuse disconnects a circuit by melting it with its own heat after the current exceeds the specified value for a certain period of time. Fuse Cutout is an electric current protector made using this principle.

Fuse Cutouts are widely used in high and low voltage distribution systems and control systems as well as electrical equipment, as short circuit and overcurrent protector, is one of the most widely used protection devices.

2.Fuse cutout consists of three main parts:

THE FUSE CUTOUT BODY,  a porcelain or a polymer insulator body that isolates the conductive portion from the supports to which the insulator is fastened.

THE FUSE HOLDER, also called the insulating fuse tube, it contains the replaceable fuse elements inside. when the contained fuse melts, it disconnects the circuit, and the fuse holder drops  and hangs from a hinge on its lower end. This hanging fuse holder indicates  that the fuse has melted and that the circuit has disconnect. The circuit can also be disconnect manually by  linemen using the hot stick.The fuse holder may be replaced by a solid blade, which would allow the fuse holder assembly to be used as a switch only.

THE FUSE LINK, also is the fuse elements. is the replaceable portion of the fuse cutout  that will melt and diconnect the circuit with its own heat when there is overcurrent went through it.

Surge Arrester

Surge arrester: An electrical device used to protect electrical equipment from high transient overvoltage during a lightning strike, and to limit the duration and, often, the amplitude of the continuing current. Lightning arrester is also sometimes called overvoltage protector, overvoltage limiter

The role of surge arrester is used to protect various electrical equipment in the power system from damages that caused by lightning overvoltage, operating overvoltage, power frequency transient overvoltage. When a communication cable or equipment is operating at normal operating voltage, the arrester is not effective and is regarded as a circuit breaker to the ground. When a high voltage occurs and endangers the insulation of the protected equipment, the lightning arrester will immediately act to direct the high voltage impulse current to the earth, thereby limiting the voltage amplitude and protecting the communication cables and equipment insulation. When the overvoltage disappears, the arrester quickly restores to its original state, making the communication line work normally.