Variable Frequency Drives (VFDs) are essential for modern automation, improving efficiency, reducing energy consumption, and giving you precise speed control. But what many engineers don’t realize is that VFDs also create electrical conditions that can stress, overheat, and prematurely damage motors — especially when long cable runs are involved.

If your system includes long motor leads, sensitive equipment, or high‑performance motors, you may be exposing your equipment to voltage spikes, reflected waves, and insulation breakdown.

That’s where MTE motor protection filters come in.

Why VFDs Can Damage Motors

When a VFD sends PWM (pulse‑width modulated) output down long cable runs, the fast switching edges can reflect back toward the drive. This creates:

Voltage spikes
High dv/dt stress
Insulation breakdown
Overheating
Bearing damage
Premature motor failure

The longer the cable, the higher the risk.

Even a perfectly sized VFD can unintentionally shorten motor life if the output isn’t properly filtered.

**SineWave Guardian® Filter**

MTE’s SineWave Guardian Filter converts VFD PWM output into a clean sinewave, extending motor life and improving system reliability.

How MTE Protects Your Motor

MTE offers a range of filters designed to smooth the VFD’s output waveform and protect your motor from harmful electrical stress.

✔ dV/dT Filters

Reduce voltage spikes and slow down the rise time of the PWM waveform — ideal for medium cable lengths.

✔ SineWave Filters

Convert the VFD’s output into a near‑perfect sinusoidal waveform — ideal for long cable runs and sensitive motors.

✔ RL Reactors

Provide impedance that reduces harmonic distortion and protects both the drive and motor.

With the right filter, you can dramatically extend motor life, reduce downtime, and improve system reliability.

What We Need to Recommend the Right Filter

To determine the correct MTE solution, we only need two details:

1️⃣ VFD Horsepower (HP)

This tells us the size of the drive and the motor load.

2️⃣ Motor Lead Length

This determines how severe the reflected wave and voltage spike issues may be.

With just these two pieces of information, we can quickly identify whether you need a reactor, a dV/dT filter, or a full SineWave filter.

Send Us Your VFD HP and Motor Lead Length

Not sure which filter your application needs? Have a long cable run or a motor that keeps failing early?

Send us your VFD HP and motor lead length — WD Engineering Sales will help you select the right MTE solution.

We support engineers across Iowa, Illinois, Wisconsin, Kansas, Nebraska, and Missouri with product selection, application guidance, and technical support.

Protect Your Motor. Improve Your System.

A VFD should improve your process — not damage your equipment. Let us help you make sure your motor is protected. Contact us today to get started.

Contact WD

Is Your VFD Protecting Your Motor?