When we talk about harmonics in electrical systems, we refer to a form of electrical “distortion.” Harmonics occur when electrical devices draw currents that are not perfectly smooth or sinusoidal, as the power grid expects (see below image). Ideally, the electrical current supplied by the grid should follow a smooth waveform, but some modern electronic devices, like variable speed drives, uninterruptable power supplies, induction furnaces, microwaves and fluorescent lamps, draw currents in abrupt, non-smooth ways. Devices with magnetic iron cores, such as transformers or generators, have traditionally been a major source of harmonic distortion. These disruptions create harmonics—waveforms at higher frequencies than the standard grid supply (50Hz in South Africa).

Equipment manufacturers are responsible for ensuring their products do not generate distortion levels beyond permissible limits, which is why EMC standards exist to prevent such issues. However, in certain cases where a user combines devices in a way that causes unexpectedly high distortion on an already near-capacity electrical network, this distortion can become significant and impact other equipment.

Harmonics are essentially multiples of the base frequency—so, if the base frequency is 50 Hz, the third harmonic will be at 150 Hz, the fifth harmonic at 250 Hz, and so on.

Why Are Harmonics a Problem?

Harmonics can lead to several problems:

• Overheating: Electrical motors and transformers can overheat due to the additional energy from harmonics, leading to premature equipment failure.
• Flickering lights: If harmonics are strong, they can cause visible disturbances like flickering in lights.
• Increased energy costs: Harmonics make the system work harder, leading to higher energy consumption and, ultimately, higher electricity bills.
• Equipment malfunctions: Sensitive electronics, such as computers or medical devices, can be disrupted by high levels of harmonic distortion.
• Unwanted Circuit breaker tripping: High levels of harmonic distortion may cause circuit breakers to trip and fuses to blow.  
• Equipment Efficiency: Frequency deviations can negatively affect equipment performance, especially for devices that rely on a stable frequency for proper operation.

By using devices like the PEL 103 to perform a comprehensive energy quality analysis, Estac’s engineers can measure harmonics in a power system and design more efficient, reliable solar energy systems that not only meet a building’s energy needs but also address any hidden issues caused by poor power quality.

In summary, harmonics are like hidden distortions in the electrical system that, if unchecked, can cause inefficiencies and damage. Identifying and addressing them with proper tools is critical to ensuring long-term energy efficiency, operational cost savings and system reliability.