Electronic devices have become an indispensable part of our lives. From smartphones to washing machines, we use them for almost everything. But have you ever wondered what makes these devices work? It's the intricate combination of various electronic components like resistors, capacitors, and inductors. One of the most important components among them is a varistor.
What is a Varistor?
A varistor is an electronic component that is used to protect devices from high voltage surges. It is also known as a Voltage Dependent Resistor (VDR) and Metal Oxide Varistor (MOV). A varistor is made of semiconductor material that exhibits a non-linear resistance when the voltage across its terminals varies. The resistance of the varistor decreases significantly when the voltage across it exceeds a certain threshold value.
Why are Varistors Important?
Varistors play a critical role in protecting electronic devices from voltage spikes or transient overvoltages. These voltage surges can occur due to lightning strikes, power fluctuations, or electrostatic discharge (ESD). If a device does not have proper protection against such surges, it can damage the sensitive electronic components, resulting in device failure or even fire.
Varistors act as an electronic switch that shorts or limits the voltage surge, protecting the device connected to it. When the voltage across the varistor exceeds a certain threshold (known as the breakdown voltage or clamping voltage), the resistance of the varistor drops dramatically. This allows the surge current to be diverted away from the device and safely dissipated.
Types of Varistors
There are several types of varistors available, and they differ in their construction, material, and applications. Let's take a look at some common types of varistors:
- Zinc-Oxide Varistors: These are the most common type of varistors and are made of a ceramic material called zinc oxide. They are widely used in electronic devices for their fast response time and high energy absorption capacity.
- Silicon Carbide Varistors: These varistors are made of a silicon carbide material and are commonly used in high-temperature applications. They have a higher breakdown voltage but a lower energy absorption capacity than zinc-oxide varistors.
- Polymer Varistors: These varistors are made of a polymer material that exhibits a non-linear resistance. They are commonly used in low-voltage applications and are known for their high reliability and stability.
Varistors are also categorized based on their clamping voltage, energy absorption capacity, and peak current handling capability. It's important to choose the right type of varistor for a particular application to ensure proper protection.
Conclusion
Varistors are an essential component in electronic devices, providing protection against voltage surges and overvoltages. They act as a switch that limits the voltage surge and diverts the energy away from the sensitive electronic components. With the increasing use of electronic devices, the demand for varistors is also increasing. It's crucial to use the right type of varistor for a particular application for optimal protection.