Variable Frequency Drives (VFDs) offer a host of useful benefits to industrial and commercial organizations, from improving productivity and precision, to reducing energy waste. But they do have some potential problems too.
VFDs can create detrimental electrical spikes and asymmetrical currents that produce excess heat. This can affect the motor insulation life, damage bearings and issues related to high frequency noise affecting other electrical equipment. If they’re not appropriately filtered, or “choked”, VFD driven equipment can eventually suffer from unexpected downtime and costly maintenance bills.
CoolBLUE inductive absorbers can help to mitigate some of the most common issues facing VFDs. These efficient nanocrystalline cores absorb high frequency damaging currents that move through an electric motor, improving longevity, and limiting problems with productivity. Read on to discover 3 of the most common VFD issues that CoolBLUE inductive absorbers can solve.
1. Motor Bearing Damage, Fluting, and Frosting
Many of the problems associated with VFD systems come from the insulated-gate bipolar transistors (IGBT) switching frequency of their common-mode output. By using IGBTs, VFDs can switch off and on creating a pulse width modulated (PWM) source to power the motor. This rapid switching creates unwanted high frequency currents that is conducted through the windings, induced into the motor frame and rotor and is characterized as “common mode noise”, discharged as current through the bearings to ground. The discharge currents create heat, breaking down the lubrication of the bearings.
Eventually, high frequency currents moving throughout the motor bearings produce an electrical discharge machining (EDM) effect. This is shown as pitting or fluting to the motor bearing raceways, while breaking down bearing lubrication. As a result, the entire motor can fail prompting significant downtime and repairs. CoolBLUE nanocrystalline cores can work to suppress common mode noise, absorbing and reducing asymmetrical currents, and maximizing system longevity.
CoolBLUE inductive absorbers can “choke” and absorb the asymmetrical electromagnetic frequency interference (EMI) and radio frequency interference (RFI) that damages motor bearings. By protecting your bearings, you can reduce maintenance costs, limit unscheduled downtime, and even make your production floor safer.
2. Overheating in the System
The wayward currents caused by VFDs aren’t only dangerous because of the impact they can have on bearings. The rapid switching transitions created by PWM outputs can lead to “over-voltages”, due to parasitic inductance and capacitance within the leads of the motor. In other words, the faster the pulses switch, the more stressed the motor windings become. This leads to an increase in noise and heat.
Too much heat in a motor can cause a range of problems with performance, including damage to the motor winding, and stress to the motor operation. Though excessive dirt and dust can create heat, this issue is also seen in unfiltered VFDs. CoolBLUE inductive absorbers can help by absorbing damaging high frequency currents before they reduce the motor life.
3. High Frequency Noise
VFDs generate high frequency “noise” (currents) carried by the power wiring to other equipment and sensors, affecting analog and data signals due to high-frequency electrical noise if they do not have the correct grounding and filtering solutions.
Case histories have shown when CoolBLUEs are installed on the line side of a VFD, high frequency currents are significantly reduced (50% or more), allowing proper operation of analog sensors and fieldbus network communications. CoolBLUE inductive absorbers reduce transient voltages and high frequency currents before they reach other control systems, limiting high-frequency noise and improving equipment reliability.
The Benefit of CoolBLUE Inductive Absorbers
Though electric motors can experience issues for a range of reasons, from poor lubrication to the presence of dirt and dust, one of the most significant issues they face is linked to VFD induced high frequency currents.CoolBLUE inductive absorbers improve the performance and durability of your machinery by minimizing the damage of high-frequency noise, and absorbing high frequency currents in the system.
Quick and easy to install, these simple solutions can help you tackle many of the most common VFD/Electric Motor system issues.