Electrical Protection Devices
Various types of electrical protection devices play a crucial role in ensuring safety and functionality in electrical systems. The most notable of these devices include:
Fuse
The fuse, also known as a circuit fuse, is an electrical component designed to protect circuits from excessive current flow. It consists of a metal strip that melts when the current exceeds a safe level. Different types of fuses are available based on specific voltage ratings, current capacities, applications, and breaking capacity.
Circuit Breaker
Circuit breakers are essential for safeguarding electrical circuits against short circuits and overload conditions that cause current surges. Their primary function is to interrupt the current flow immediately when a fault occurs. Circuit breakers can be reset either manually or automatically and are utilized in applications involving low current and high voltage.
Residual Current Circuit Breaker (RCCB)
The Residual Current Circuit Breaker (RCCB) enhances circuit safety by detecting issues in the power source. It disconnects the circuit within 10 to 15 milliseconds to prevent electric shocks. RCCBs are typically installed alongside other protective devices, such as Miniature Circuit Breakers (MCBK), which guard against overload currents. Additionally, RCCBs feature a test button to verify the functionality of the current detection and a reset button.
Poly Switch (Resettable Fuse)
Commonly referred to as a poly switch or resettable fuse, this electronic device protects circuits from overcurrent risks. It operates based on principles similar to thermistors or thermal resistors in certain contexts. Poly switches are integrated into power devices in computers and specialized applications in nuclear and aerospace technology.
Additional Electrical Protection Devices
Here are further examples of devices employed to protect electrical and electronic circuits that have not been previously mentioned:
- Inrush Current Limiter: This device prevents excessive current flow during the startup of certain equipment, safeguarding other devices such as circuit breakers and fuses by mitigating high inrush currents through a thermostat mechanism.
- Metal Oxide Varistor (MOV): Also known as a Voltage Dependent Resistor (VDR), this electronic device varies its resistance according to the applied voltage. The relationship between voltage and resistance is inverse; as voltage increases, resistance decreases.
- Gas Discharge Tube (GDT): A gas-filled tube containing electrodes within a glass encasing and heat insulation. These tubes function through phenomena related to electrical discharge in gases and activate by ionizing gas under specific voltage levels.
- Lightning Arrester: This device protects against lightning strikes by diverting surges of high voltage safely to the ground when electrical surges occur.