Electrical Symbols of Protection Devices

Electrical power systems supply continuous electricity to different users. A good system has smaller number of fluctuations. More often the faults occurring on systems lead to greater destruction and are a nightmare for Engineers. The priority of power Engineers is to reduce these faults and protection devices play a keen role in this case. Here are the 7 basic symbols of these. Fuse and Circuit Breaker symbols are from IEC standard.


  • Fuse: It provides protection to electrical equipment.
  • Circuit breaker: Provides protection from over-current. Its construction is somewhat complex.
  • Surge Arrestor: It protects the equipment from lightning over-voltage transients.
  • Overcurrent Relay: A protection device which protects against over-current. Mostly it uses instrumentation transformer for current sampling.
  • Directional overcurrent relay: Provide a directional protection.

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