Protection components

The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.

This page covers protection devices.

Summary

Various devices provide protection against excessive and potentially dangerous or damaging currents, voltages or temperatures. Some are single-use and must be replaced when blown but others are self-resetting.

Safety

Warning03.png
Protection devices protect you against fire and malfunction and may limit collateral damage following an initial fault. They must always be replaced by a device with a similar (ideally, identical) rating, and must never be bypassed or deactivated.

Introduction

The commonest and most familiar protection device is the fuse, which prevents an excessive and potentially dangerous current from flowing, but devices also exist to absorb an excessive voltage which might cause damage or malfunction, as well as to cut the supply in the case of overheating, such as a kettle boiling dry.

Fuses

Conventional wire fuses

Polyfuses

Over-voltage Protection

Varistors

Spark gaps and neons

Suppressor capacitors

Thermal fuses

Single-use thermal fuses

Resetable thermal fuses

External links

  • External links (if any) as bullet points.
  • If non, delete this section.