Different Types of Circuit Protection Devices

The components involved in circuit protection vary across industries, especially when considering how much circuit magnitude differs among devices. Circuit protection devices prevent power loss by pinpointing the location of the issue and isolating it. In this blog, we will discuss some of the most common types of circuit protection devices on the market and why you should have them installed.

Basic Circuit Protection

Diodes are the most basic form of circuit protection. They are unidirectional devices with low resistance to current flow in one direction and high resistance to current flow in the other direction. Such capabilities mean that they can limit the direction of current flow based on the component’s orientation. Protection circuits take advantage of diodes to prevent current from flowing in an improper direction and causing damage to sensitive components.

There are a wide range of diode technologies apart from protection circuits, including transient voltage suppressors (TVS), ESD suppressors, Schottky, and vacuum tubes. Moreover, depending on the specific device, some diodes operate in voltage ranges from 0.1V to 100kV with varying current capacities.

Overvoltage Protection

As their name suggests, overvoltage circuit protection systems ensure that, if the source voltage exceeds the intended amount, the circuit remains protected. As such, transient voltage spikes can be combated with the following devices: 

  • TVS diodes are used in circuits to protect surge-prone devices from unexpected and sudden overvoltage conditions or transients. Also called zener diodes, TVS diodes can offer voltage protection in the range between 1V to 15kV with a response time of one picosecond.
  • ESD suppressors (diodes) protect devices from electrostatic discharge, which can damage sensitive IC equipment. When an ESD strike takes place, ESD diodes create a low impedance path to direct current away from the IC and to the ground. 
  • Varistors also protect circuits from transient voltage spikes; however, their resistance varies according to voltage in a non-linear fashion. The most common form of varistor is a metal oxide varistor (MOV), and they are more cost-effective than TVS diodes, but are prone to degradation over time as they necessitate higher clamping voltage.
  • Thyristors, or thyristor surge protection devices (TPSDs), are solid-state components that enable current flow in the event of sudden voltage on the gate of a device. Because of their robust nature, thyristors find use in high voltage circuits. 

Different Types of Circuit Breakers and Fuses

In this section, we will outline some of the most commonly used circuit breakers and fuses. 

  • Circuit breakers are designed to automatically actuate to prevent a circuit from overloading or shorting, as well as to interrupt current flow in systems. 
  • Fuses are found in an array of applications ranging from highly complex manufacturing systems to simple automotive lighting, and they rely on high-current situations to be effective. To create a fuse, you need a metal wire with very low resistance that, when exposed to a high-current signal, melts and becomes disconnected from the circuit to stop operation, protecting components down the line. 
  • Resettable fuses respond to current transients. When they encounter higher-than-normal currents, they increase in temperature to reduce their conductivity. This increase in resistance is maintained until the high-current source is eliminated, and the fuse cools down enough to return to normal low-resistance operation.

Thermal Cutoff Switch & Fuse

A thermal cutoff switch and fuse belong in their own category because of the unique way in which they provide circuit protection. More specifically, thermal cutoffs depend on external inputs to trigger circuit protection. However, they rely on a one-time fusible link that, when exposed to ambient temperature over the melting temperature of the link, will fail to protect the circuit. In contrast, thermal switches operate like a resettable fuse or a reed switch, and they restrict the flow of current in the case of specified ambient temperatures. 


Industrials Domain is a leading distributor of circuit protection devices that have been sourced from reliable manufacturers. With countless high-quality products on our database, customers have a plethora of options to choose from. Get started today and see how Industrials Domain can serve as your strategic sourcing partner! 


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