What is a Varistor?
A varistor is an electronic component that is designed to protect electronic circuits from voltage surges or spikes. It is a type of resistor that exhibits nonlinear resistance characteristics, meaning that its resistance changes with changes in voltage. Varistors are made from a ceramic or metal oxide material that has a high resistance at low voltages but rapidly decreases as the voltage increases beyond a certain threshold.
Varistors are commonly used in electronic devices and equipment to protect them from voltage transients. These transients can occur due to lightning strikes, power surges, or electromagnetic interference. Varistors are able to detect the voltage spike and reduce it to a safe level, preventing damage to the electronic circuit.
How Does a Varistor Protect Circuits?
When a voltage surge occurs, the varistor conducts the excess current and diverts it to ground. This is achieved by the varistor’s nonlinear resistance characteristic, which causes its resistance to decrease as the voltage across it increases. This allows the varistor to absorb the excess energy and protect the electronic circuit from damage.
Varistors are designed to be self-protecting, meaning that they will fail safely if the voltage surge is too high. This is because the varistor’s resistance will drop to a very low level, causing it to draw a large current and blow a fuse or break apart. This protects the electronic circuit from the high voltage surge, preventing damage or failure.
Examples of Varistor Applications
Varistors are used in a wide range of electronic devices and equipment, including power supplies, surge protectors, motor controllers, and telecommunications equipment. They are also used in automotive applications to protect electrical systems from voltage spikes caused by alternator failure or lightning strikes.
In addition, varistors are used in voltage regulators to protect sensitive electronic components from voltage fluctuations. They are also used in gas discharge tubes to suppress voltage spikes in high-voltage circuits.
Benefits of Using a Varistor in Circuit Protection
The use of varistors in electronic circuits provides several benefits. Firstly, they are cost-effective and easy to implement as they are available in a range of sizes and shapes to suit different applications. Secondly, they provide reliable protection against voltage spikes, preventing damage to electronic circuits and equipment.
Thirdly, varistors can reduce downtime and repair costs by protecting equipment from damage caused by voltage surges. Finally, varistors can improve the overall reliability and performance of electronic devices and equipment, ensuring that they operate as intended and without interruption.
