FlexSine 120 Sine Wave Filters (6-120 Hz)

One Filter. Induction and PM Motors. No De-rate.

Product Overview

Motor advances are driving the market to make the switch to faster spinning, higher efficiency PM motors. These higher speeds lead to higher frequency harmonic distortion at the output of the drive, forcing de-rating of competitors sine wave filters, and leading them to require switching frequencies that de-rate the drive. The FlexSine 120 Sine Wave Filters allow for:

  • One filter for both Induction and PM Motors
  • No de-rating of the filter up to 120 Hz (180 Hz with minimal de-rating)
  • No drive de-rate due to lower switching frequencies
  • Low Audible Noise
Harmonic Design

<5% @ 2.5 kHz

Voltage Range

Up to 500 V

Fundamental Frequency

6 - 120 Hz (Up to 180 Hz with de-rating)

Switching Frequency

2.5 kHz Nominal 2.0 kHz Minimum

Current Range

100 - 960 A

Overload Capability

150% rated current for 1 minute

Maximum Ambient Temperature

50 °C (122 °F) (Higher with de-rating)

Motor Cable Length

Up to 15,000 feet

Enclosure Options

Modular Panel NEMA 3R Cabinet

Agency Recognitions

cЯUus 1446 Standard

FlexSine 120 Highlights

  • Single Design for IM and PM Motor Operation: The FlexSine 120 is the only sine wave filter designed specifically for operation with today’s 60 Hz induction motor applications as well as tomorrow’s high frequency permanent magnet (PM) motors.
  • Avoid Equipment De-rates At High Frequency: Competitors’ solution to high frequency PM motors is to force you to buy a larger filter and switch the VFD at 5 kHz. Not only are you forced to pay more for the larger filter, the 5 kHz switching frequency de-rates the drive, increasing up-front costs further by requiring a larger drive. The FlexSine 120 is different. Due to a unique patented design and proprietary materials, the FlexSine 120 allows you operate at 2.5 kHz, avoiding any drive de-rate. The FlexSine 120 also is rated at full current up to 120 Hz (up to 180 Hz with 0-15% de-rate).
  • Upgrade to PMM with Existing Equipment: The FlexSine 120 allows you to use your current drive to upgrade to PMM frequencies. Simply switch out your existing sine wave filter with an appropriately sized FlexSine filter to start reaping the benefits of PMM.

Sine Wave Filter Advantages

  • Motor Protection: Harmful square waves, voltage spikes, and harmonic distortion are all filtered from the inverter output, reducing motor heating, wear, and winding stress, providing critical motor protection.
  • Maximum Motor Lead Length: Reflected voltage waves occur when motor lead lengths reach or exceed a characteristic length of the system, which is dependent on the voltage rise times (dV/dt) in the cabling. By filtering the PWM waveform to a near perfect sinusoidal waveform, CTM sine wave filters minimize dV/dt, allowing for longer motor lead lengths (up to 15,000 feet in certain applications).
  • Electric Fluting (Bearing Current): Common-mode (bearing) current can have disastrous effects on induction motors, leading to electric fluting and premature bearing failure. CTM offers the only sine wave filters that do not introduce common-mode currents.
  • Low Audible Noise: Due to superior materials and geometric shapes, magnetostriction-induced noise is significantly lower in CTM filters.
  • Integrated Thermal Management: CTM FlexSine filters are outfitted with fans for thermal management and low operating temperature.

Cost to Upgrade to 120 Hz

Following our competitor recommendations, upgrading to 120 Hz can be a costly endeavor, with filter de-rates of at least 25% and drive de-rates of at least 20% (due to the recommended 5 kHz switching frequency). These recommendations become even more costly with field retrofits, as the drive and filter are essentially scrapped.

However, there is another option. By installing a CTM FlexSine 120 filter now, you not only get the benefits of a low cost 60 Hz sine wave filter, you also unlock the ability to upgrade to a 120 Hz PM motor at no additional cost, whether that is an initial or future plan. Buy for today, be prepared for tomorrow.

FlexSine 120 Operating Range

The FlexSine 120 product line is electrically designed to provide -17 dB attenuation at a switching frequency of 2.5 kHz. The product line is thermally designed to operate at 120 Hz and minimum 2 kHz switching frequency. The chart to the right displays the maximum switching frequencies at various fundamental frequencies.

With an operating switching frequency of 2.0 kHz the attenuation drops to -12.4 dB and allows for more harmonic distortion at the output of the filter. It is up to the customer to determine if this is an appropriate amount of filtering for the application.

FlexSine 120 Sine Wave Filters (6-120 Hz)