In electronics, ‘noise’ is an unwanted high-frequency disturbance or interference with the electrical signal. Electrical noise is transient (temporary) or permanent and can be classified as either:
- Common Mode Noise – a disturbance that occurs between the power supply lines and earth (i.e. phase-to-earth or neutral-to-earth)
- Normal Mode Noise – a disturbance that occurs between phase and neutral.
Noise can come from within the system itself (internal noise), where it is caused by faults in the switchgear and the wider electrical design, or from an outside source.
This external noise includes lightning and electrical storms, electromagnetic interference from currents in cables, and frequency interference from equipment like radio transmitters.
Electrical noise can disrupt circuit operation and potentially damage equipment.