Fuses help ensure the safety of electronic systems. They prevent damage caused by overcurrent, overvoltage or short circuits. These components are needed in a wide variety of devices, from smartphones to industrial equipment. In this article, we will cover the most common circuit protection components and how they work.
Fuses
Fuses are disposable protective devices. They contain a metal wire that melts when the current is exceeded.
- Their purpose is to protect against overvoltage and short circuits.
- They are often used in power supplies, chargers, and household appliances.
If a circuit breaker blows, it must be replaced.
For information on reclosable fuses, see “Self-Regenerating Fuses” below.
To purchase fusesand fuse components, visit the DRex Electronics website.
Self-regulating fuses (PPTC)
These fuses, also called polymer PTC fuses, are self resetting after a fault is cleared.
- Application: multiple overcurrent protection.
- Most commonly found in: USB ports, batteries, and consumer electronics.
They are popular in modern portable electronics because they don’t need to be replaced after traveling.
Read our article to learn more:
👉 Battery fuses: the secret key to reliable electronics.
TVS diodes (transient voltage suppression diodes).
TVS diodes protect against transients and voltage spikes. They react extremely quickly – on the order of a nanosecond.
- Applications: Protection of sensitive circuits against electrostatic discharge (ESD) and overvoltage.
- Typical applications: USB and HDMI interfaces and communication lines.
TVS diodes are critical components for ESD protection of data and signal lines.
Varistors (MOV)
Metal oxide varistors (MOVs) absorb high energy transient voltages. They change their resistance depending on the voltage level.
- Applications: Overvoltage protection in AC circuits.
- Typical applications include power supplies, televisions and industrial equipment.
MOVs are often used in conjunction with fuses to provide more reliable protection.
Electrostatic Discharge Protection Equipment
These components protect small sensitive parts from electrostatic charges. They are usually installed near the entrance/exit door.
- Applications: to protect microcontrollers and integrated circuits.
- Often found in: touch screens, USB connectors, Ethernet connectors and sensors.
They are small but very important in Internet of Things devices, wearable devices and medical electronics.
Circuit Breakers
Circuit breakers mechanically shut off large currents. Unlike fuses, they can be reset without replacement.
- Applications: protection of high-power circuits and equipment.
- They are often found in: industrial equipment, switchgear and HVAC installations.
More detailed information can be found in our article:
Description of circuit breakers: types, principles of operation and application.
Current limiters and current limiters (NTC thermistors).
These resistors change their value depending on the temperature. They limit the inrush current when switched on.
- Application: inrush current protection.
- Theyare often used in power supplies and LED drivers.
Circuit protection
In the absence of circuit protection:
- Components may overheat.
- If the circuit is not protected.
- Devices may malfunction.
- Risk of fire.
Using the correct components extends the life of the equipment and ensures user safety.
Where to buy circuit protection components
DRex Electronics offers a full range of circuit protection products including:
- Fuses
- TVS diodes
- Electrostatic Discharge Suppressors
- Fuses
- PPTC Reversible Fuses
