, , ,

The power of harmonic filters

Toshiba harmonic filters

Toshiba looks at how harmonic filters are helping reduce distortion on electrical networks, and when the best time is to apply them.

Businesses of all types rely on clean electricity to power their operations. But it is not about provenance, or its generation from a renewable source. It is about the quality of the electricity.

The wrong kind of harmonics

In music, harmonics can create a richer, fuller sound. These are the good kind of harmonics.

On an electrical network, harmonics are a distortion of the electrical current that takes up capacity in cables and transformers. This can cause power quality problems that, over time, work together to damage a business’ profitability.

This compromises its ability to operate at optimum levels, creating more opportunity for failure.

The main culprit

Variable speed drives (VSD) are one of the main culprits contributing to harmonic distortion.

It occurs when a VSD converts AC to DC power using a diode rectifier, which draws harmonic current from the network. This current leads to distortion in the voltage and propagates through the network.

While harmonic distortion from a single unit won’t necessarily be a problem, that is not what happens in practice. Plants and facilities usually have multiples VSDs, or larger units, which create larger and more complex harmonic problems for engineers to content with.

How harmonic filters solve the problem

As a manufacturer of VSDs, Toshiba is well-placed to help businesses tackle their harmonic distortion issues head-on.

With an in-depth understanding of the equipment, there are four key solutions the company provides that will reduce, or eliminate, harmonics from a business’ electrical network.

Toshiba manufactures VSDs with built-in harmonic filtering, utilising a DC choke that goes a long way to reduce harmonic current.

The company can also add to the built-in filter by installing an AC line reactor. Connected to the input of the VSD, this enhances the effects of the DC choke and further mitigating harmonics.

Instead of a standard drive with a diode rectifier, Toshiba also provides VSDs with an active front end (AFE). This can virtually eliminate harmonics altogether.

Toshiba also provides active harmonic filters. Capable of virtually eliminating harmonics, typically one filter connects into the motor control centre and occupies a smaller footprint than a collection of AFE drives.

Alternatively, they do nothing. Because, sometimes, there are no appreciable harmonic effects caused by VSD. It is a matter of knowing why.

A lot to learn

While there’s a growing awareness about harmonic disturbance in the industry, there’s still a lot to be learned.

The biggest issue that is often seen is engineers simply throwing money at the problem to solve it; by installing harmonic filters to make sure the problem doesn’t occur in the first place. And while this arguably does work, it also adds increasing complexity—and cost.

With its comprehensive understanding of VSD technology, Toshiba takes the time to undertake the right calculations first.

The company pays close attention to the drives it is installing, understanding what the drives are generating and how much distortion they’re going to create.

This allows it to identify which solution will work best, whether it’s a DC choke, an AC reactor solution, or an active harmonic filter, and then including this at the right place in the design.

With extra planning, based on Toshiba’s vast, real-world experience with its own VSD technology, this can save a business thousands of dollars.

A balancing act

Toshiba’s harmonic filters are purpose-designed to complement its VSD technology.

VSDs don’t necessarily cause problems but their popularity, and growing numbers and sizes of the componentry, means more harmonic distortion.

Having the right harmonic filter technology is important, but having an engineering team who can advise customers on the optimal solution is also key.

For more information, visit here.

Subscribe to Energy Today for the latest project and industry news.

Send this to a friend