When it comes to maintaining power quality in their devices, VFD manufacturers prefer to use Passive Harmonic Filters to suppress harmonic currents and decrease voltage distortion occurring in the sensitive parts of the power system.
With the growing use of VFDs in distributed power generation, a critical problem emerges – harmonic distortion. If generated harmonics get injected into the grid, it can cause malfunctioning of sensitive equipment connected on the same line. The use of well-designed harmonic filters can mitigate this critical risk.
PURESINE Three Phase Passive Harmonic Filters from EMIS are a popular choice among VFD manufacturers worldwide. They provide an economical solution for Harmonic mitigation in Power Systems by maintaining THiD 5% in compliance with current and voltage requirements of IEEE 519.
Harmonic Distortion and its impact
Harmonics are currents and voltage waveform distortions in the power supply. Harmonics occur in integer multiples of the fundamental (supply) frequency – 50 Hz in India/Europe, 60 Hz in North America.
A distorted waveform creates heat in the power delivery equipment that can cause severe damage to both domestic and industrial equipment using the utility power supply. Harmonics are created due to the presence of non-linear loads which draw non-sinusoidal currents from an essentially sinusoidal voltage source. This leads to corruption of the supply voltage in the main power lines.
There are several nonlinear equipment sources that can potentially trigger harmonics in the line, affecting all other connected devices. These devices include rectifiers, inverters, electronic starters, and battery chargers, home appliances, SMPS, office automation devices, and so on. Since such devices are a dominant part of our industrial and home environment, harmonic distortions are inevitable. Therefore, necessary corrective action has to be taken at the design level itself.
Total harmonic distortion (THD) is a measurement that tells you how much of the distortion of a voltage or current is due to harmonics in the signal. THD should typically(not always) be as low as possible. The acceptable threshold of THD is under 10% and varies according to the application. The total harmonic distortion for voltage and current are represented as THvD and THiD respectively.
Harmonic distortion may impact power quality in several ways:
- Distorts the sine wave shape of the fundamental on the grid. Increased Harmonics increases the phase angle difference between Voltage and
- As the grid has protection equipment, harmonics may give false
- Increases heating losses, torque pulsations
- Affects the life of the equipment connected to the grid
- Can cause overheating, resulting in a potential fire hazard
- Can result in irregular fuse operation, capacitor failure, electronic equipment malfunction, flickering lights, and telephone interference
- Voltage Harmonics with high peak values can weaken insulation in cables, windings, and capacitors
- Current Harmonics in motor windings can create Electromagnetic Interference (EMI)
Use of Harmonic Filters – simple and effective
Active harmonic filters are very effective for systems that have multiple loads, but are expensive, complex, and space-consuming. On the other hand, Passive harmonic filters offer a rugged, inexpensive, low maintenance option. They are typically L-C filters installed in a shunt arrangement on the line side of
the inverter. They are tuned to resonate at a single frequency or through a band of frequencies. They could be tuned somewhat below the 5th harmonic, which is the largest component of harmonic distortion. A significant amount of 7th harmonic distortion will also be absorbed. Additional filters tuned to higher-order harmonics may also be used.
PURESINE Three Phase Passive Harmonic Filters from EMIS
Three Phase Passive harmonic filters from EMIS are designed and manufactured to provide an economical and sturdy solution for harmonic mitigation in power systems. These filters effectively maintain THID 5% in compliance with the current and voltage requirements of IEEE 519.
Passive harmonic filters being a harmonic absorption type, absorbs the harmonics from both downstream as well as upstream within its range. Thus they prevent the current harmonic from circulating and getting absorbed within the equipment and also stop it from flowing back to the upstream power grid.
They are effective in suppressing harmonic currents and decreasing voltage distortion occurring in the sensitive parts of the Power system. Their primary advantages include:
- Consistently maintain THD under 5%
- Rugged, low cost, low maintenance
- Very effective in reducing losses
- Prevents overheating of components
- Prevents transformer failures
- Eliminates nuisance tripping of circuit breakers
- High attenuation of individual harmonics
- Help in the power factor correction
- Specifications and standards compliance with UL 61800-5-1, IEEE-519
Apart from application in inverter systems, Passive harmonic filters can also be used in various kinds of adjustable speed drive systems, SMPS, DC chargers, UPS, power grids, pumps and fan applications, HVAC, and other industrial automation systems.
EMI Solutions Pvt Ltd is an ISO 9001-2015 and 14001-2015 certified company that exclusively caters to EMI-related requirements. We deliver both standard manufactured and custom designed EMI filters and components.
EMIS is also a leading service provider of Electromagnetic Compatibility (EMC) and Electromagnetic Interference (EMI) engineering and compliance services. Apart from comprehensive EMI/EMC testing facilities, we also offer expert consultancy support for engineering, design analysis, and technical training. Our endeavor is to provide our customers all EMI-related solutions under one roof.
For more information, visit www.emisindia.com
