PASSIVE HARMONIC FILTERS

Harmonic currents occur in power networks due to non-linear loads, such as computers, frequency converters and UPS equipment. Among other things, the harmonic currents increase losses and cause malfunctions in electrical devices. A passive harmonic filter is required when a specific (for example the 5th or 7th frequency) harmonic is too large for the network.

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FILTERING HARMONICS

Harmonic currents occur in power networks due to non-linear loads, such as computers, frequency converters and UPS equipment. Among other things, the harmonic currents increase losses and cause malfunctions in electrical devices. A passive harmonic filter is required when a specific (for example the 5th or 7th frequency) harmonic is too large for the network.

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FILTERING HARMONICS

As the name indicates, a passive harmonic filter is designed for a network with a high level of harmonics, in order to improve the power quality by filtering out certain harmonic frequencies (for example the 5th). In addition, the passive harmonic filter improves the power factor in the same way as a detuned filter capacitor bank. With moderate harmonics, using the less expensive detuned filter capacitor bank instead of the passive harmonic filter is recommended. When the network has for example 5th and 7th harmonic frequencies, the solution is to install separate suitably dimensioned harmonic filters for each frequency. A suspected high level of harmonics can be confirmed with measurements.
POWER QUALITY MEASUREMENTS
Suodatinparistot yliaaltovirtoja yliaaltopitoisuus
Suodatinparistot yliaaltovirtoja yliaaltopitoisuus

THE MOST COMMONLY USED PASSIVE HARMONIC FILTERS

  • 5th harmonic filter (250 Hz), 150 kVAr – 300 kVAr
  • 7th harmonic filter (350 Hz), 150 kVAr – 300 kVAr
  • Cabinet dimensions 800 x 600 x 2000 (w x d x h)
  • Voltage for example 400 V or 690 V
  • Temperature class: 0–35 °C
HARMONICS

Harmonics

A functioning electric current and voltage should follow a sine wave pattern (BLACK). Some electrical devices cause distortions in the sine wave of the power network supplying the device. These distortions in the sine wave are called harmonics. Harmonics occur as multiples of the base wave frequency (DIFFERENT COLOURS). Harmonics compound into the base wave, causing a distorted sine wave (RED).

Sources of harmonics

Known sources of harmonics include frequency converters, switched-mode power supplies, thyristor switches, home and office electronics, UPS equipment, LED lights, and discharge lamps.

Harm

The harm caused by harmonics include increased disturbances in the power network and to the devices of electricity users, as well as in the reduced capacity of the equipment. Harmonics also cause faulty meter readings as well as malfunctions to automation equipment and protective relays.

CONTACT US

CONTACT US

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Teemu Lindgren
Sales Director
+358 40 575 9800
teemu.lindgren@tkf.fi
Partnerships and European sales
Eero Nerto
Sales Manager
+358 400 777 185
eero.nerto@tkf.fi
Finnish sales, technical support and measurements
Tampereen Kondensaattoritehdas Oy
Hyllilänkatu 15, FI-33730 Tampere
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