120Hz Sine Wave Filters, FlexSineTM120

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

Product Overview

Stop Trying to Make Silicon Steel “Work”…

Motor advances are driving the market to switch to faster spinning PM motors. These higher speeds lead to high frequency harmonic distortion at the output of the drive. Our competitors’ filters overheat under this additional stress, forcing them to derate their filters. Furthermore, competitors often demand higher drive switching frequencies (to decrease THID), which then requires a drive derating.

Harmonic Distortion

<5% THVD @ 2.5 kHz

Voltage Range

Up to 500 V

Fundamental Frequency

6 - 120 Hz (Up to 180 Hz with derating)

Switching Frequency

2.5 kHz Nominal 2.0 kHz Minimum (See Flexsine 120 Operating Range Chart)

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 Integrated 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 Derating 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 derates 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 derate. The FlexSine 120 also is rated at full current up to 120 Hz (up to 180 Hz with 0-15% derate).
  • 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.

120Hz Sine Wave Filters, FlexSineTM120