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Single Phase Harmonic Filters

Single Phase Harmonic Filters

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Single Phase Harmonic Filters (Type SLPF and Type THF) 120-690 volts 50/60hz

APQ offers two types of harmonic filters for use with 1-phase non-linear loads. Type SLPF is a low pass filter that attenuates all harmonic frequencies and Type THF is a 3rd Harmonic blocking filter that reduces the third Harmonic from both phase and neutral conductors.

APPLICATION: Single phase filters are suitable for reducing harmonics in both industrial and commercial applications such as office buildings, schools, casinos etc. Type SLPF Low Pass Harmonic Filters are normally used with variable frequency drives that are supplied from a single phase power source such as submersible pumping, irrigation, fans, blowers, and other motor/drive applications. Type THF 3rd Harmonic Filters are typically used for 1-phase loads such as computers, slot machines, video monitors, video games, switch-mode power supplies (SMPS), etc.


  • Type SLPF Low Pass Harmonic Filters

    Type SLPF Low Pass Harmonic Filters are designed to filter virtually all harmonic frequencies and achieve low levels of total harmonic current distortion. All harmonic frequencies are filtered.

    Single Phase Low Pass Harmonic Filters Results

    Single Phase Low Pass Harmonic Filters Results

    Low Pass Harmonic

    1 Phase Low Pass Harmonic Filters

    1 Phase Low Pass Harmonic Filters


  • Type THF 3rd harmonic Filters

    Type THF 3rd Harmonic Filters are specifically designed to minimize 3rd harmonic current and reduce the 3rd harmonic current that flows on the neutral conductor. 3rd Harmonic is significantly reduced.

    Single Phase 3rd Harmonic Filter Results

    Single Phase 3rd Harmonic Filter Results

    3rd Harmonic Filters

    Hard-Wire Type

    Hard-Wire Type

    Plug-in Type

    Plug-in Type


Harmonics in Single Phase Power Systems:

Harmonic distortion caused by single phase power electronics equipment is typically higher in magnitude and more difficult to solve than for 3-phase equipment.

  • More harmonic frequencies are produced by 1-phase loads than for 3-phase loads.
Specific harmonic frequencies produced when non-linear loads exist in either 1-phase or 3-phase
 3rd5th7th9th11th13th15th17th19th21st23rd
1-phase
3-phase    
  • The 3rd harmonic (which does not normally exist in balanced three phase systems, even with non-linear loads), is much higher than all of the other harmonic frequencies and often has a magnitude that is 90% of the fundamental current.
  • The third harmonic currents from all three phases of a 3-phase/4-wire power system add together in the neutral conductor and cause very high third harmonic current to flow on shared neutral conductors.
  • Higher magnitude of total harmonic distortion (THD-i)

Harmonics in 1-phase vs. 3-phase

Typical magnitude of individual harmonics for non-filtered 1-phase non-linear loads.

Typical magnitude of individual harmonics for non-filtered 1-phase non-linear loads.