Did you know that terminating a VFD cable differs from terminating other shielded cables? With a typical shielded cable, shield conductivity is not designed to minimize high-noise currents. That is not so with VFD cables. VFD cables are designed to minimize electrical environmental noise challenges for industrial and hazardous locations. So, correctly terminating the VFD cable and its shield is essential to a system’s performance and reliability.
Contractors terminate the shield in a gland during a standard termination process. Landing ground currents on a gland release electrical noise, which a VFD cable is designed to harness. This can lead to increased bearing currents at the motor or harmful panel currents if the cable is grounded at the motor disconnect or panel ingress. Furthermore, since there is no jacket on the VFD cable in the enclosure, the unshielded cable releases harmful noise.
Using a kit to reshield the VFD cable in the enclosure is not convenient or effective, as the bonded gland has already released harmful noise. A contractor would have to reshield the VFD cable and effectively isolate the reshielded but unjacketed cable for it to be effective—a lot of extra work for nothing.
According to Peter Cox, P.Eng, Belden Global Director, Industrial Projects and Product Line Manager for VFD Cables, successfully terminating a VFD cable can be accomplished by:
- Choose products that seal and isolate the cable grounds through the cable jacket and carry appropriate ratings based on industry standards.
- Use UL-certified cable glands design for your specific environment, cable type and application. Be sure your hazardous location glands or connectors include the required epoxy seal for the environment.
- Use pass-through glands to prevent the release of noise currents from the shields and grounds and minimize ground loops that can damage motor bearings.
Whether you need more tips for terminating a VFD cable or have other cable questions, we’re here to help. Contact us today!