Electrical principles - Current effects

Non-physical

Current can produce the following non-physical effects:

• heat
• chemical
• magnetism.
  

Heat

When a current is passed through a conductor, it generates heat. The greater the current value, the more heat is generated. Increasing cable size will reduce resistance in a conductor and limit heat.

Advantages:

• lights, heaters, kettles, toasters, welders.

Disadvantages:

• fire, melting of cables, inefficient motors.

Chemical

When a current is induced into a metal it can cause a chemical reaction called corrosion.This reaction occurs in three stages: oxidation, reduction and rust formation.

Metals can be protected against corrosion by using anti-corrosive cold galvanising primers. It is a regulation in the Australian Standards AS/NZ3000 for the main earth clip to use this protection.

Advantages:

• electroplating.

Disadvantages:

• corrosion.

Magnetism

When a current flows through a conductor, a magnetic field is produced around the conductor. The strength of the magnetic field depends on the amount of current flow and the number of turns if the conductor is wound in a coil.

Advantages:

• motors, transformers, contactors/relays, circuit breakers.

Disadvantages:

• induction, electrical noise.