VFD Cable Termination Guide
A VFD cable is excellent for VFD systems because it helps to prevent systemic issues, such as cable malfunctions, over-voltage concerns, and even motor failure. Using VFD cables keeps VFD machines functioning efficiently for longer. However, all of these benefits are not effective if VFD cables are terminated in the wrong way. Here are a couple of suggestions on how to terminate VFD cables correctly.
What is a VFD Cable Termination?
A VFD cable termination or any cable termination is the act of connecting the wire or the cable to the device. Naturally, a VFD cable is connected to the VFD machine. Therefore, the term "termination" as it applies to cables, refers to the process of installation, or installing the cable into the machine.
This process is not to be confused with the word "termination" in common English meaning of this word, which means the action of ending or finalizing something. In the termination process, a VFD cable is not utilized; it becomes attached to the machine.
Why is Correct VFD Cable Termination Crucial?
The correct VFD cable termination is important for several reasons. The issues in the VFD machines result from common mode currents and EM radiation. A VFD cable that is terminated correctly helps to limit the current that is traveling through the grid and has proper shielding from the motor. Finally, the cable grounds the motor.
When a VFD cable is terminated and used incorrectly, the VFD machine system, which is supposed to be efficient, stops working most effectively. Instead, it begins to release harmful currents in the most vulnerable places.
Common Rules of VFD Cable Termination
- Ground intermediate termination is to be avoided at all times.
The grounds are supposed to be terminated only at the drive and the motor. The reason for this is that intermediate terminations are proven to reduce the ability of the shielding system to protect from electromagnetic interference. One of the most common varieties of intermediate termination occurs at a terminal block. While it seems logical at first glance, it is the one with the potential to cause the most harm, and it should be avoided.
Termination at the ground and motor does not compromise the ability of shielding to sustain EMI. It is the only proper termination way.
- When terminating the grounds, use the isolating block and a separate safety ground to connect.
This action serves as a necessary extra protection to ensure that the ground termination process will be smooth.
- The shield and jacket of the cable should be intact.
If the shield and jacket are intact, there are no jumping points for common mode currents. It is best to make sure that they are intact before initiating the entire process. This is the best-case scenario in which you will not need the termination kit. Using termination kits should be treated as a last-minute effort in case the proper cable termination process fails. If this is your scenario, you can opt for a termination kit.
- Avoid terminating grounds and shielding at the enclosure ingress.
This rule is necessary because if these components are terminated at the ingress, the noise reaches the sensitive equipment, which impacts the safety of the VFD system.
- Pick High-Quality VFD cables from trusted manufacturers
High-quality VFD cables ensure a successful termination process as they follow the designated standards for VFD cables. These are UL 1685 and several flame tests, such as ICEA T-29-520, IEEE 383, IEEE 1202, ICEA T-29-520, and IEC 332-3.
Nassau National Cable sells VFD cables from a trusted manufacturer that will not fail you throughout the termination process.
