11KV Drop Cut Fuse Cut Outs are widely used for protection / isolation of distribution transformers, This specification not only stipulates the electrical and mechanical requirements of good quality drop out fuse cut outs but also specifies important constructional features to ensure uniformity and proper quality.

What are its components?

A cutout consists of three major components:

Body:

The frame which supports the fuse tub/blade and is mounted to the crossarm or bracket. The insulator body on this frame can be either polymer or porcelain material. The live connector parts are also mounted to the ends of this frame.

Fuse Holder:

Known as the fuse tube or “door” that contains the fuse link. This piece acts as a simple switch. When the fuse operates, the fuse holder will drop open disengaging the switch from the line. This ensures any downstream circuits are electrically isolated.

Fuse Link:

Also known as an element, is the replaceable portion of the product that extinguishes due to higher than normal current transfers.

How do they work?

A current surge from a customer circuit or a transformer will cause the fuse inside the tube to expand and melt.  Once the fuse reaches maximum current capacity it breaks and this energy is thrown out of the bottom of the tube and disconnects the transformer from the line by the tube dropping out of the upper contact and swinging down on the hinge. The physical indication that the fuse has been extinguished and needs to be replaced is seen when the tube swings open and remains in a downward orientation.