Importance Of Installing Harmonic Filters For VFD

Harmonic distortion is an unwanted side effect of using non-linear loads in an electrical system. To mitigate this, harmonic filters are used to eliminate or reduce them effectively. There are a lot of potential causes of this harmonic distortion. One of the major causes in most systems is variable frequency drives (VFDs). This blog explores the reason why it is important to install harmonic filters for VFDs.

Basic Design Of A VFD

To understand why VFDs cause harmonic distortion, it is important to first understand the basic design of this device. A VFD comprises a diode bridge converter, a DC bus, and an IGBT output inverter.

Coming to the diode bridge converter contains a 6-pulse rectifier, which is responsible for converting the incoming AC voltage into usable DC voltage. The DC bus stabilizes the AC voltage, and finally, the IGBT output inverter utilizes the voltage from the DC bus to create the desired variable frequency.

Out of these components, the 6-pulse rectifier is the major cause of creating harmonic distortion in VFDs. How this occurs is explored in the next segment.

How Do VFDs Cause Harmonics?

As stated above, the 6-pulse rectifier causes harmonics within the VFD and negatively impacts the electrical system. To convert the input AC into usable DC, the rectifier draws in a non-sinusoidal input current, which is not proportional to the input voltage. Consequently, it distorts the supply voltage and creates unwanted power quality issues. This is why it is essential to install harmonic filters for VFD.

Negative Effects Of Harmonics

The harmonics created by VFDs can have the following negative effects:

- Create interference in certain circuits
- Can lead to the overheating of transformers
- Can cause complete failure of the capacitor bank
- Can trip the circuit breaker continuously

To mitigate this, an active harmonic filter is usually considered the ideal choice.

Want to know which active harmonic filter is best-suited for your needs? Contact us at ADM Engineering Inc. today. As the only distributor of REVCON harmonic filters in Miami, Florida, our products and quality service guarantee positive results. Call us at 877-236-8337 for more details.