Medium voltage current limiting fuse is a protective device used in medium voltage power systems. Here is a detailed introduction about it:

Working Principle:

Thermal effect of current: The medium voltage current-limiting fuse uses a metal conductor as the fuse link connected in series in the circuit. When there is overload or short-circuit current in the circuit, the fuse link heats up due to its own heat generation and the temperature rises rapidly. When the heat reaches the melting point of the fuse link, the fuse link melts, thus breaking the circuit and playing a protective role.

Arc extinguishing function: When the fuse link melts, an arc will be generated. The fuse is usually filled with arc-extinguishing media such as quartz sand. The arc will be subject to strong deionization and cooling effects in the arc-extinguishing medium, so that the arc is extinguished quickly and further damage to the equipment caused by the arc is prevented.

Structural Composition:

Fuse tube: This is the core component of the fuse, and the fuse link is installed inside. The material and size of the fuse link determine the rated current and fusing characteristics of the fuse.

Contact base: Used to connect the fuse tube and the circuit to ensure the normal transmission of current.

Terminal block: Convenient for connecting the fuse to the external circuit.

Support insulator: Plays a supporting and insulating role to ensure the safe operation of the fuse in a medium voltage environment.

Base plate: As the installation foundation of the fuse, the fuse is fixed in the equipment or switch cabinet.

Main Characteristics:

High current-limiting characteristic: It can quickly cut off the circuit before the short-circuit current reaches the peak value, limit the short-circuit current to a lower level, and thus effectively protect electrical equipment from the impact of short-circuit current.

Fast fusing: It has a fast action time and can respond to fault current in a short time, cut off the circuit in time, and reduce the damage to equipment caused by faults.

High reliability: The structure is relatively simple and there are no complex mechanical parts and electronic components, so it has high reliability and stability.

Good selectivity: Appropriate rated current and fusing characteristics can be selected according to different protection requirements to achieve accurate protection of specific circuits4.

Application Scenarios:

Transformer protection: Commonly used for the protection of distribution transformers. When there is a short-circuit fault inside the transformer, the medium voltage current-limiting fuse can melt quickly and cut off the faulty circuit to protect the transformer from damage.

Motor protection: Can be used for short-circuit protection of medium voltage motors. When a short-circuit fault occurs in the motor, the fuse can quickly cut off the circuit to prevent the motor from being burned due to excessive short-circuit current6.

Power line protection: Installed on medium voltage power lines for short-circuit protection of the lines. When a short-circuit fault occurs in the line, the fuse can cut off the circuit in time to avoid the expansion of the fault.

Capacitor protection: Used for the protection of medium voltage capacitor banks. When there is an internal fault or overcurrent in the capacitor bank, the fuse can melt quickly to protect the safety of the capacitor bank and other electrical equipment.