Product Overview

The emergence of permanent magnet (PM) motors has led to increased installation efficiencies across the board. However, PM motors typically require a high frequency, variable speed drive (VSD). With an-always on rotor magnetic field, PM motors are more susceptible to wear and damage caused by harmonic distortion. Traditional silicon-steel laminated inductors exhibit high losses at high frequencies, and, quite literally, cannot handle the heat. Compared to conventional technology, S2F High Frequency Sine Wave Filters offer…

  • INCREASED EFFICIENCY with high frequency VSD systems
  • Perfect for use with PERMANENT MAGNET MOTORS
  • HALF THE SIZE & WEIGHT for a smaller footprint and easier integration and installation
  • HIGH RELIABILITY due to cooler, more efficient filter operation

Product Specs

Nominal Operating Voltage:
480 V
Motor Frequency:
0 - 200 Hz
Switching Frequency:
5 - 20 kHz
Current Range:
130 - 1,680 A
Estimated Motor HP Range:
100 - 1,400 HP (Induction Motor)
130 - 1,680 HP (Synchronous Motor)
Overload Capability:
150% rated current for 1 minute
Maximum Ambient Temperature:
50°C (122°F) (higher with de-rating)
Harmonic Voltage Distortion:
<1.5% with 12% THD input
Insertion Loss (Voltage Drop):
3.3% @ 200 Hz
Motor Cable Length:
15,000 ft or more
Enclosure Options:
Stand-Alone Cabinet (NEMA 3R)
Pedestal Cabinet (NEMA 3R)

The Problem

The future of power semiconductors keeps moving towards higher switching frequencies to achieve higher efficiencies. This trend will only increase as SiC and GaN technologies become more and more affordable. Furthermore, the increased utilization of permanent magnet motors have created demand for high-speed drives (with higher fundamental frequencies), which can be used to realize the advantages of PM motors.

Conventional laminated silicon-steel inductors exhibit extremely high core losses at high frequencies. These high core losses create low efficiency, high operating temperatures, and dubious reliability. Traditional filtering technology is ill-prepared to meet these next-generation power quality issues.

The Solution

Compared to conventional laminated silicon-steel filters, S2F High Frequency Sine Wave Filters utilize advanced magnetic materials with low core losses. These lower core losses allow CTM to efficiently filter high frequency power signals that conventional technology cannot. Moreover, due to low power losses (dissipated as heat), CTM filters operate at lower temperatures, increasing reliability. CTM Magnetics is silicon-carbide ready. We have the solutions you need for your high frequency power quality issues.



  • Motor Life: Harmful square waves, voltage spikes, harmonic distortion, and common-mode noise are all filtered from the VFD output, reducing motor heating and wear, bearing currents (fluting) and stress, thereby extending motor longevity.
  • System Efficiency: Since the motor receives a near-perfect sinusoidal waveform, almost all of the power it receives is converted in to useful work. Additionally, low insertion loss (less than 3.3%) maintains system efficiency.
  • Filter Reliability: CTM filters maintain lower temperatures, increasing life and reliability.
  • Maximum Lead Length: By filtering the carrier frequency from the voltage signal, motor lead lengths of 15,000 feet or more are possible.
  • Power Density Our exclusive NEMA 3R Pedestal Cabinet offers the highest power density available on the market.



  • Power Loss: Due to a unique patented design and proprietary materials, S2F High Frequency Sine Wave Filters operate at higher efficiencies than conventional filter technology at high frequencies, decreasing power loss, minimizing dissipated heat, and reducing total cost of ownership.
  • Electric Fluting (Bearing Current): Common-mode (bearing) current can have disastrous effects on motors, leading to electric fluting and premature bearing failure. CTM offers the only sine wave filters with built-in common-mode current mitigation.
  • Design Footprint: At half the size and weight of laminated silicon-steel technology, CTM filters take up less space and are easier to integrate into existing systems.

S2F High Frequency Sine Wave Filters

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