A resistor is an electric circuit used to restrict the amount of current that can pass through. Essentially, it’s a resistive part.
A varistor is a resistor that alters the resistance by changing the applied voltage. It is also called a voltage-dependent resistor. Semiconductor devices are non-linear in this case.
They have a lower resistance as the voltage rises. When the voltage is raised too high, their resistance decreases dramatically.
Letting the extra current flow through the varistors ensures that the circuit does not become damaged. A varistor’s current-voltage properties aren’t linear, either. It usually comes in a disc package. If you are looking for high-quality varistors, you can check out this trusted site: https://www.tme.com/us/en-us/katalog/varistors_29/
Let’s explore how varistors work below.
Table of Contents
Varistor Working Principle
Because it defies Ohm’s law, a varistor is not the same as an ohmic resistor. Being non-ohmic is the reason it became known as a non-linear resistor or a voltage-sensitive resistor.
As a result of the varistor’s high resistance, relatively little current passes through the devices when forward biasing is used. The rated voltage of the varistor is the voltage at this point.
Voltage rises cause the varistor’s resistance to drop rapidly; it allows current to flow through the varistor when the applied voltage exceeds its rated voltage.
It acts as a capacitor when the applied voltage is lower than its rated voltage, and so it stores charge. As the voltage increases, the resistance of variable resistors changes in a non-linear fashion.
Construction of Varistor
Metal oxide and silicon carbide make up the vast majority of these materials.
As the name implies, the varistor’s body is constructed of silicon carbide, as the name suggests (SIC). Before the metallic oxide varistor’s arrival, this was the most used method of transport. High-power, high-voltage applications are the primary use cases for these devices.
As a result of the high standby current drawn by these varistors, a series gap is necessary to reduce the standby power consumption.
Among varistors, metallic oxide varistors are the most prevalent. Metal oxide matrix incorporates zinc oxide is into this device which made it famous.
Bismuth, cobalt, and manganese are just a few of the most often utilized metals. Varistors based on metal oxides are superior to those found on silicon carbide because they are better at protecting against voltage transients.
It gets squeezed between two metals. Zinc oxide grains are held in place between the two metal plates by 10% metal oxides of cobalt, bismuth, and manganese. To connect the terminals or leads, it uses two metal plates.
Applications of a Varistor
Varistors protect electrical and electronic circuits by allowing excessive current flow through them. Varistors can be linked parallel with electrical or electronic components in the course.
The varistors behave as a short circuit and provide virtually no resistance as it applies voltage to the circuit.
The following are just a few of the many uses for these varistors:
- Protection for phone lines and other communication lines
- Equipment transient suppression in the radio communication industry
- Power strips with surge protectors
- A surge protector for your cable TV system is required.
- Electrical power supply safety
- Security for microprocessors
- Protective measures for electronic devices
- Protection of low-voltage circuit boards
- Protection for car electronics from transient voltage surges
- Protection from high-intensity AC in industrial settings
Key Takeaways
Applied voltage dramatically alters the resistance of a varistor, which is a type of resistor.
These are two-terminal semiconductor components that safeguard electrical and electronic equipment against overvoltage transients as a form of the resistor.
These types of resistors protect high-current power electronic devices utmost. Although there are a variety of varistors to choose from, we’ll focus on the Metal oxide varistor (MOV).
Varistors are pretty unique and helpful tools to be used in electric works.
