CTM Magnetics

Harmonic Filters

Harmonic filters are becoming more & more common in motor drive applications. To understand why, we need to first look at vfd’s, why they are important, how they work, and the problems they create.

Why VFD’s Are Important:

  1. VFD’s improve the efficiency of motor applications – resulting in energy savings
  2. VFD’s allow you to adjust the speed of electric motors to maintain constant torque load.
  3. They provide controlled starting and stopping of the motor.

How VFD’s Work:

  1. VFD’s convert line current from AC to DC, then back to AC
  2. VFD’s control the speed of a motor by varying the output frequency delivered to the motor
  3. VFD’s vary the output frequency by using IGBT’s that switch at higher frequencies.

Unintended Drawbacks of VFD’s:

  1. Converting AC to DC or DC to AC creates harmonic distortion
  2. Harmonic distortion can negatively affect the power quality of utility grids and surrounding equipment connected to the same grid. Harmonics also can cause damage to motors requiring repair resulting in costly downtime.
  3. Utility providers are starting to enforce strict IEEE-519 guidelines for customers that utilize VFDs

GridHawk Harmonic Filters


CTM Magnetics GridHawk passive harmonic filters are a size and cost optimized solution that solves harmonic distortion and guarantees IEEE-519 compliance. With a built in cooling system, sealed contactors, and a robust capacitor safety circuit, GridHawk filters provide year round peace of mind.

  • 0 – 5% THVD (Grid Voltage Distortion)
  • No Derate
  • Full IEEE-519 Compliance

GridHawk® HD

GridHawk® HD passive harmonic filters are designed for extreme levels of grid voltage distortion 15% without requiring a derate. Guaranteed performance in even the most demanding environments.

  • 0 – 15% THVD (Grid Voltage Distortion)
  • No Derate
  • Full IEEE-519 Compliance

GridHawk® XD

GridHawk® XD passive harmonic filters are specifically engineered to handle staggering levels of grid voltage distortion, soaring up to an astounding 22%, all without the need for any derating.

  • 0 – 22% THVD (Grid Voltage Distortion)
  • No Derate
  • Full IEEE-519 Compliance



Running a VFD with a GridHawk Harmonic Filter Solves:

Harmonic Distortion

GridHawk Harmonic filters significantly reduce harmonic distortion.

IEEE-519 compliance

GridHawk harmonic filters reduce harmonic distortion to below 5% ensuring IEEE-519 compliance.


GridHawk harmonic filters offer best in class performance & reliability at low cost.

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