We all rely on Variable Frequency Drives (VFDs). They’re essential tools for saving power and giving us the precise control our operations demand. But as any seasoned tech or electrician knows, VFDs are not always a friendly piece of equipment.
The truth is, while a VFD is saving you energy, it’s also constantly attacking the rest of your electrical system. This hidden electrical stress is the leading cause of early component failure, unexpected tripping, and that costly, frustrating word: downtime.
If you want to keep your systems running reliably, you have to protect them from the VFD’s two biggest threats.
The VFD’s Double Attack on Your Plant
A VFD causes trouble at both ends: on the power line coming into the drive, and on the cable going out to the motor.
Attack 1: The Dirty Input Power (Harmonics)
When your VFD takes the incoming AC power and converts it, it creates a distorted, “dirty” current waveform, we call this harmonic distortion. This garbage current gets pushed back onto your power system.
- It Kills Your VFD: The biggest victim is often the drive itself. Harmonics cause excessive heat and ripple current that hammer the DC bus capacitors inside the VFD. These capacitors are the weak link. Stress them too much, and the VFD goes down, guaranteed.
- It Burns Up Equipment: This dirty power also stresses the rest of your gear, like transformers and power cables, reducing their life and eating up system capacity. Without fixing it, you can’t meet industry power quality standards like IEEE-519.
Attack 2: The Motor Beating (Voltage Spikes)
On the motor side, the VFD doesn’t send a smooth signal. It sends high-speed, sharp bursts of voltage (PWM). The faster the drive switches and the longer the cable run is, the bigger the problem gets.
- It Kills Your Motor: These bursts bounce off the end of the cable, creating massive voltage spikes at the motor terminals. This repeatedly slams the motor’s winding insulation until it breaks down. The result? A costly, premature motor failure that takes your process offline.
The Solution: A Two-Part Defense System
You need specific tools designed to tackle these two problems. Relying on basic reactors just doesn’t cut it anymore. We look at MTE’s filters as the robust, layered defense needed for true uptime.
Defense 1: The Input Cleaner — Matrix® AP Harmonic Filters
This filter solves the “dirty power” problem. It’s an advanced solution because it uses Adaptive Passive Technology.
What this means for you: It’s smart enough to adapt to varying load conditions. It doesn’t matter if your motor is running at 30% or 100% speed, this filter keeps the harmonic distortion extremely low.
- Maximum Protection: It consistently holds the current distortion (THID) to 5% at full load, easily meeting the IEEE-519 standard.
- VFD Survival: By eliminating the harmful ripple current, the Matrix AP dramatically reduces the stress and heat on your VFD’s capacitors, ensuring the drive itself lives longer.
Defense 2: The Motor Shield — dV E-Series Motor Protection Filters
This filter solves the “voltage spike” problem. You install this one between the VFD and the motor.
What this means for you: It’s a dedicated shield that intercepts the destructive voltage pulses and smooths them out before they reach the motor.
- Winding Protection: It provides what we call “triple protection” by preventing the reflective wave, reducing the voltage rise time, and limiting the dangerous peak voltage.
- Less Maintenance: This is the easiest way to ensure you’re not pulling motors out of service early. It extends the life of both your motor and your expensive power cable. Plus, the newer E-Series models are smaller and run cooler, making them a breeze to install in crowded panels.
The Bottom Line
A reliable VFD system isn’t just about the drive itself. It’s about how you manage the power quality problems it creates.
By installing both an MTE Matrix AP on the input and a dV E-Series on the output, you’re creating a comprehensive system that protects your most vulnerable and expensive assets. You get to keep the energy savings of the VFD without the constant fear of component failure.
Have you had a VFD capacitor fail recently, or are you constantly swapping out motors? Let us know what you’ve found to be the weakest link in your system.
Ready to Protect Your System?
These essential MTE products are available at Vanco Electrical Solutions.
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Email: sales@vancoelectrical.com
Phone: (905) 305-7702