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In the continuous pursuit of energy efficiency and sustainability, the HVAC industry is embracing significant technological advancements. Among these, the use of Variable-Frequency Drives (VFDs) stands out. VFDs, which regulate the voltage and frequency supplied to electric motors, are a pivotal tool in reducing energy consumption in HVAC systems, making them a preferred choice for diverse settings including offices, hospitals, and data centers.

The Role of VFDs in HVAC Systems

At Mainstream, we acknowledge the crucial role of VFDs in contemporary HVAC systems. VFDs optimize the speed of HVAC system motors to meet the demand, ensuring the system uses only the necessary amount of energy, thereby curbing wastage and saving costs.

VFDs, while advantageous, create power line harmonics. Harmonics are distortions in the power line waveform, usually quantified as a Total Harmonic current Distortion (THDi%). Generated by the rectifier within VFDs and comparable devices, harmonics can trigger a range of problems, including device failures, nuisance trips of breakers and fuses, unstable operation of backup generators and sensitive electronics, and flickering lights.

The Impact of Harmonics

It’s essential to understand that the repercussions of harmonics can be substantial. Excessive harmonics can overheat motors, shortening their lifespan and necessitating expensive replacements. Furthermore, harmonics can disrupt the operation of other equipment, leading to malfunctions or outright failures. Additionally, power companies set limits on the distortion that any building or facility can introduce to the grid, with violations incurring hefty fines. It may also necessitate limiting the use of critical equipment until the situation is rectified.

Mainstream’s Approach to Harmonics Mitigation

At Mainstream, we focus on simple, robust techniques to mitigate these harmonics. Our solutions focus on configurations that meet IEEE519 and EN61000-3-12 compliance, ensuring Total Harmonic Distortion (THD%) is maintained below 5%. For example, when harmonics are a concern and simplicity matters, we can use traditional six-pulse drives with harmonic filters to meet IEE519 harmonic requirements, this simple configuration is highly reliable and guaranteed to be compliant. Users that demand the highest level of energy efficiency and/or IEE519 compliance over a wide range of operating conditions, can choose to use Ultra-low harmonic drives. These VFDs use electronically controlled rectifiers to reduce harmonic distortion to within IEEE519 levels.

Building and Facility Level Considerations

Importantly, dealing with harmonics requires a comprehensive understanding of a building or facility’s complete power system. Mainstream can provide panels that comply with IEE519 standards but they, often, will only be one piece of the puzzle. It is imperative that the building be assessed as a whole when meeting harmonic requirements is necessary. Considering the building or facility as a whole and implementing smart strategies vs over spec’ing individual components will add reliability and cost savings to your harmonic mitigation efforts. Harmonic audits and consultation with experts will typically pay dividends in final installed costs in facilities with high load counts.

While VFDs and other energy-saving technologies play a significant role in the future of HVAC, these technologies come with their challenges. By understanding and mitigating the harmonic effects our panels will impart on your building’s electrical infrastructure, we at Mainstream can ensure that our HVAC systems are as efficient, reliable, and compliant as possible.