Power harmonics refer to unwanted electrical frequencies or currents that can distort the shape of the voltage and current waveforms in an electrical system.These harmonics are typically integer multiples of the fundamental frequency of the power supply. In most cases, power systems operate on a fundamental frequency of 50 or 60 Hz, depending on the region.

Common sources of power harmonics include nonlinear loads, such as:

1. Electronic Devices. Many modern electronic devices, such as computers, variable frequency drives (VFDs), LED  lighting, and uninterruptible power supplies (UPS), are nonlinear in nature. They draw current in short pulses, which can introduce harmonics into the electrical system.
2. Rectifiers & Inverters. Devices like rectifiers and converters, which are used to convert alternating current (AC) to direct current (DC), can generate harmonics. This is because they often draw current in a non-sinusoidal manner.
3. Switching Power Supplies These power supplies, commonly found in electronic equipment, convert AC to DC and operate by rapidly switching transistors on and off. This switching action can introduce high-frequency harmonics.

The presence of power harmonics can have several negative effects on electrical systems and equipment:

1. Voltage Distortion Harmonics can distort the voltage waveform, leading to a poor power quality. This can cause voltage sags, swells, and flicker, which can damage sensitive electronic equipment.
2. Increased Current Harmonics can increase the current flowing through the electrical system, leading to overheating of conductors and transformers. This can reduce the efficiency of the system and potentially cause equipment failures.
3. Transformer Overheating Transformers are particularly sensitive to harmonics because they can overheat and experience premature failure if subjected to excessive harmonic currents.
4. Resonance In some cases, harmonics can cause resonant conditions in the electrical system, leading to further amplification of harmonic currents and voltages.

Power quality standards and regulations exist in many regions to limit the level of harmonics that can be present in the electrical system, ensuring that power quality remains within acceptable limits for reliable and safe operation.

The allowable harmonics as provided by the Philippine Distribution Code (2001) are specified in the following sections:

3.2.4.4 At any User System, the THD of the voltages hall not exceed five percent (5%) during normal operating conditions.

‍3.2.4.5 At any User System, the TDD of the current shall not exceed five percent (5%) during normal operating conditions.

‍

In the example of the Smappee screenshot of the LVSG, this load is clearly surpassing the 5% current harmonics of TDD, while also at times surpassing the 5% THD limit too.

‍

Legacy mechanical techniques have been deployed for decades to mitigate the effects of power harmonics including harmonic filters and line reactors.Mechanical techniques are expensive and have short life-spans.

‍

Have you assessed the harmonics behind the four walls of your facility? Smappee’s Infinity power monitoring system offers an XL data license option providing current and voltage spread over a 5-minute interval as well as harmonics insights up to the 19^th harmonics.

As detailed above, it is specific loads which contribute to the degradation of power quality and trying to identify this can be cumbersome and tricky, specially when a single PQA can only measure a single 3-phase load. Not anymore! With Smappee a total of 9 3-phase loads can be monitored under a wye configuration and 14 under a delta. This means that an electrical engineer can undertake a comparative analysis in real time and historically across the MDP and then on specific loads, to rapidly identify where the source of the harmonics, or power factor degradation, or current surges, or unbalanced loads or…. Well, there is so much more Smappee can do.

Smappee provides both a live harmonics card and a historical harmonics card. This allows to compare the possible degradation of a particular load over various different time periods. As well as between loads. There is no other solution on the market at Smappee’s price point providing these exceptional insights, to ensure the lights stay on. Get in touch to find out more.

‍