High-voltage current-limiting fuses are capable of limiting short-circuit current. Once the short-circuit current exceeds the melting current, the fuse will open the circuit.

High-Voltage Current-Limiting Fuse

High-voltage fuses provide short-circuit protection and overload protection for circuits and equipment. They cut off the circuit by melting low-melting-point metal wires or strips (also known as fuse elements). Featuring simple structure, low cost and easy maintenance, they are widely applied.

High-voltage fuses are classified into indoor type and outdoor type by installation location; by current-limiting performance, they fall into current-limiting type and non-current-limiting type.

A high-voltage current-limiting fuse is filled with quartz sand inside its porcelain tube. When short-circuit current melts the fuse element and generates an electric arc, the narrow gaps between quartz sand particles constrict the arc column. Combined with the cooling effect of quartz sand, the arc is extinguished before the short-circuit current reaches its steady value, achieving the current-limiting effect.

Main Parameters and Characteristics of High-Voltage Current-Limiting Fuses

1. Rated Voltage: The voltage that the high-voltage current-limiting fuse can withstand continuously after interruption. It shall be equal to or higher than the rated voltage of the equipment or line.

2. Rated Current: Includes the rated current of the fuse body and the fuse element, referring to the permissible continuous carrying current. Normally selected at 1.5 ~ 3 times the rated current of protected equipment.

3. Rated Breaking Capacity: The capability to reliably interrupt overload or short-circuit current under fault conditions, expressed by breaking current or breaking capacity.

4. Insulation Level: Usually specified by power-frequency withstand voltage and lightning impulse withstand voltage.

5. Ampere-Second Characteristic: The relationship between the operating time of the fuse and the current passing through it, supplied by the manufacturer. This characteristic is critical for protection selectivity; otherwise, malfunctions such as undesired upstream tripping may occur.