By Eileen Harvey
Servo and variable frequency drive (VFD) cables are the backbone of modern automation, robotics and motion control systems. However, even the most robust and high-quality cables can suffer from premature failure if they are not properly installed and maintained. Factors such as incorrect routing, inadequate shielding practices and exposure to harsh environmental conditions can compromise the integrity of these cables. For instance, improper bending or twisting during installation can cause strain on the wires, leading to potential short circuits. Furthermore, exposure to extreme temperatures, moisture or chemicals can deteriorate the cable’s materials, making them susceptible to electrical faults and operational inefficiencies.
To mitigate these risks and ensure the longevity of servo and VFD cables, it is essential to implement best practices during installation and maintenance. This includes carefully planning the cable routing to avoid sharp bends and pinch points, as well as utilizing appropriate shielding techniques to protect against electromagnetic interference (EMI). Regular inspections should be conducted to identify any signs of wear, damage or environmental stress that could affect cable performance.
Preparing for Installation
Before laying down cables, proper preparation is essential. Start by ensuring you fully understand the cable specifications. Every servo or VFD cable is manufactured with defined voltage, frequency and temperature ratings. For instance, TKD Kabel’s Kaweflex® shielded EMC-optimized VFD cables are rated for up to 0.6/1 kV and carry UL/CSA certifications. Knowing these specifications helps ensure compatibility with your system’s electrical and environmental requirements.
Next, gather all the tools you will need for a smooth and accurate installation. Common essentials include cable cutters and strippers, torque wrenches, shield-termination kits and insulation testers. Having the proper tools on hand not only improves efficiency but also reduces the likelihood of installation errors.
Finally, always inspect cables thoroughly before installation. Look for any physical damage, such as cracks in the jacket or bends that may have occurred during storage or handling. Even minor defects can undermine safety and long-term reliability, so any damaged cable should be removed from use immediately.
Cable Routing Best Practices
Routing is one of the most overlooked but critical steps.
- Maintain proper bend radius: Never exceed the manufacturer’s recommended bend radius. For example, bending too tightly can break shielding and insulation.
- Separate power and control cables: Always run VFD power cables apart from low-voltage signal or encoder cables to reduce EMI.
- Avoid mechanical stress: Use cable trays, conduits or drag chains where necessary.
- No sharp edges: Route cables away from sharp metallic corners that can cut into insulation.
Shielding and Grounding Guidelines
Servo and VFD cables typically incorporate foil or braid shields to suppress EMI, but improper grounding can reduce their effectiveness. For VFD applications the shield should be grounded at both the drive and motor ends to create a continuous path for high-frequency noise. Shields should never be left floating since ungrounded shielding is a common mistake that can worsen EMI problems. Using EMC-rated connectors also helps ensure secure grounding and reduces leakage. An example of this approach can be seen in TKD Kabel’s Kaweflex 2x Shielded EMC-Optimized VFD Cables.
Connector and Termination Practices
Even a high-quality cable can perform poorly if it is terminated incorrectly. Installers should use proper stripping tools to avoid nicking conductors and select lugs and connectors designed specifically for VFD and servo applications. All terminations must be tightened to the manufacturer’s recommended torque since connections that are too loose can cause overheating and those that are too tight can damage conductors.
Environmental Protection Considerations
Industrial environments often expose cables to oils, chemicals or UV light, so choosing the proper jacket material is essential for durability. PVC and PUR jackets offer strong resistance to oils and solvents, making them suitable for harsh industrial locations. Outdoor installations require UV-stabilized jackets, while wet or washdown areas call for cables that include water-blocking compounds for added moisture protection.
Maintenance Best Practices
Routine inspections should look for cracks, cuts or discoloration that may indicate wear. Terminations must be checked regularly since loose connectors can lead to arcing and overheating. Periodic insulation testing with a megohm meter helps ensure electrical integrity, and infrared cameras can be used to detect developing hot spots before they lead to failure.
Common Installation and Maintenance Mistakes to Avoid
- Using the wrong cable type (e.g., power cable instead of VFD-specific cable).
- Over-tightening ties that damage insulation.
- Ignoring voltage and temperature ratings.
- Skipping shield grounding leads to system EMI issues.
Interesting Facts
- Up to 80% of VFD cable failures are due to poor installation rather than cable quality.
- Shielded cables can reduce EMI by more than 90% when grounded correctly.
- Preventive maintenance can extend cable life by 30 to 40%, reducing downtime costs significantly.
FAQs About Servo and VFD Cable Installation
Q1: Why can’t I use standard power cables for VFD applications?
A: Standard power cables lack the shielding and construction required to handle high frequency switching noise from VFDs, which can cause EMI and motor issues.
Q2: How often should I inspect VFD and servo cables?
A: A visual and electrical inspection every 6 to 12 months is recommended, especially in harsh environments.
Q3: What happens if cable shields are not grounded properly?
A: Improper grounding leads to EMI, driving faults and communication errors in control systems.
Proper installation and maintenance of Servo and VFD cables ensure maximum efficiency, longer lifespan and reduced downtime in industrial automation. Following best practices in routing, shielding, grounding and environmental protection can make the difference between a reliable system and one plagued with failures.
When sourcing cables, choose high-quality options such as TKD Kabel’s Kaweflex EMC-optimized servo and VFD cables, engineered for durability and EMI suppression.
Explore the full range of TKD Kabel through L-com. We’ll fill your orders fast, with same-day shipping on all qualified, in stock, online orders received Monday through Friday before 5 p.m. EST. For TKD-related inquiries, connect with our U.S-based TKD expert Eileen Harvey at eharvey@infiniteelectronics.com.
