Electrical noise is unwanted high-frequency oscillations generated in the electrical system. The electrical noise distorts the fundamental voltage and current waveforms, resulting in power quality issues. The poor power quality causes:
Permanent damage to the sensitive electronics loads
Malfunction and erratic behavior of computerized loads
Increased maintenance and energy usage of the loads
Internally generated noises is about 70-85%, while the externally generated noises is about 15-30%
The electrical noise is classified into two categories based on its origin of generation 1) external and 2) internal.
Internally generated noises constitute about 70-85% of the total transients in a facility. The sources of the internally generated transients are:
Load switching
Nonlinear load behavior such and VFDs and PLC
AC-DC power conversion
Starting and stopping loads
Arcing faults (ground)
Discharge of inductive loads such as transformers, motors
Contactors, relays, and circuit breaker operation
Externally generated noises remain at 15-30% of the transients. The sources of externally generated surges are:
Lightning – both direct and indirect hits
Utility initiated grid and capacitor switching
Again, the internally generated noise is 85%, while the externally generated noise is 15%. Learn more about the switching noise from the nonlinear loads here.