Varistorid

Varistors, short for variable resistors, are electronic components designed to protect circuits from voltage surges and transient overvoltages. They are nonlinear resistors that exhibit a high resistance under normal operating conditions but have a low resistance when subjected to a high voltage. This property makes them ideal for surge protection in various applications, including power supplies, telecommunications, and industrial equipment.

Varistors are typically made from zinc oxide (ZnO) or silicon carbide (SiC) and are available in various shapes and sizes, including discs, beads, and tubes. They are characterized by their voltage-current (V-I) characteristics, which show a sharp increase in current at a specific breakdown voltage. This breakdown voltage is known as the varistor's clamping voltage and is a critical parameter in selecting the appropriate varistor for a given application.

The primary function of a varistor is to divert excess current away from sensitive components during voltage surges, thereby preventing damage. They are often used in conjunction with other protective devices, such as fuses and circuit breakers, to provide comprehensive protection against electrical faults. Varistors are widely used in power electronics, telecommunications, and industrial control systems due to their reliability, low cost, and ease of integration into circuits.

In summary, varistors are essential components in modern electronics, providing robust protection against voltage surges and transient overvoltages. Their nonlinear resistance characteristics and wide range of available types make them versatile and effective in various applications.