What Can VFD Cables do for your Drive System?

Posted on Wednesday, August 20, 2014 by Justin Dubow

We’ve talked about VFD technology and the benefits it provides to motors and drives, so now let’s take a look at VFD cables and how they enable these benefits. 

A high-quality VFD Cable should:

  • Reduce the negative effects of harmonics, power distortion, and transient noise on drive system components & surrounding equipment
  • Have a low resistance to ground so that energy build up from the motor windings and circulating bearing currents can be mitigated.
  • Have low capacitance in order to reduce the reflected wave phenomena and improve transmission distance
  • Be able to withstand the harsh operating conditions sometimes caused by the drive system

All in all, the role of VFD cable is to provide the most attractive path for potentially harmful currents to return to the drive with minimal disturbance to the surrounding networks and instrumentation.

Let’s take a step back and address why tray cables are not a preferred cable type for motors and drives.  First off, tray cables have inadequate insulation to withstand voltage spikes encountered during VFD operations.  Tray Cables also often have PVC/Nylon insulation that can start to degrade quickly due to the voltage spikes common in VFD applications.  Tray cables also have inadequate shielding and grounding systems to deal with radiated and conducted noise which are also common with VFD, hence the importance of shielding with VFD applications.

Having effective shielding is important for VFD applications, specifically for the protection against two different types of noise, radiated and conducted. Radiated noise interferes with data and control signals while conducted noise can cause the motor to behave erratically.  Additionally, shielded cable may help reduce shaft voltage and induced bearing currents in certain applications. Another benefit is that the increased impedance of shielded VFD cables may help extend the distance that the motor can be located from the drive without the addition of motor protective devices such as terminator networks.

We will discuss Alpha Wire’s advantages when it comes to VFD cables in our next post.


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