Variable frequency drive (VFD) cables are specially designed cables that connect VFDs to three-phase AC motors. They play a critical role in variable speed motor control systems by minimizing electrical noise interference and ensuring proper operation. This guide provides a comprehensive overview of VFD cables, including what they are, how to terminate them, when they should be used, and Variable frequency drive cable offerings from CLEF Industries.
What is VFD Cable?
VFD cables are shielded cables engineered to work seamlessly with variable frequency drives and the motors they control. They have a number of design features that make them ideal for VFD applications:
- Three power conductors for three-phase power
- Grounding conductor
- Overall metallic braided shield to minimize electrical noise
- Durable and flexible jacket resistant to oils and chemicals
The shielding in a VFD cable is a key component. It helps prevent electrical noise generated by the VFD’s high switching frequencies from interfering with system operation. The shield dissipates this noise safely to ground.
Using properly shielded VFD cables is highly recommended when installing variable frequency drives. The benefits include:
- Flexible Durability – VFD cables are extra flexible to withstand constant motion and vibration. Their jackets resist abrasion, oils, and chemicals for long service life in industrial settings.
- Electrical Noise Reduction – The braided shield provides up to 90% noise reduction versus unshielded cables. This prevents control issues, downtime, and damage.
- Wide Operating Temperatures – Rated for dry temperatures up to 90°C, Variable frequency drive cables ensure stable power delivery in hot environments. Cold-resistant versions are designed for wet or submerged uses down to -40°C.
- Safety – VFD cables meet flammability standards for operation in cable trays and confined spaces. Their voltage ratings are designed to handle VFD voltage spikes.
Properly specified Variable frequency drive cables tailored to the application are critical in VFD systems. They permit longer motor cable runs, minimize downtime risks, and ensure the system operates as intended.
How to Terminate VFD Cable
To realize the benefits of VFD cables, proper termination practices are a must. Here are step-by-step guidelines for terminating Variable frequency drive cables:
1. Select the Right VFD Cable
- Choose cable voltage and temperature ratings suitable for the VFD system. 600V and 1000V ratings are common. Verify conductor temperature rating meets the maximum ambient temperature.
- Match the cable amperage capacity to the drive and motor full load amps with safety margin. Standard sizes from 10 AWG to 500 kcmil are available.
- Pick jacket type for the environment. Options like TC-ER provide extra chemical, abrasion and crush resistance.
2. Cut the Cable to the Required Length
- Measure the cable routing distance between the VFD and motor. Leave extra length for stress relief bend radius.
- Cut the cable to length using sharp cable cutters. Clean the jacket edge of any burrs or nicks.
3. Strip off the Outer Jacket
- Make a ring cut through the outer jacket 3-4 inches from cable end, and lengthwise slit to the cut end. Remove jacket section.
- Twist off the exposed braided shield wires. Cut them flush with the remaining jacket.
4. Strip the Insulation of Individual Conductors
- Strip 1/2″ of insulation off each power conductor. For the ground wire, strip insulation back further so it extends past the other conductors.
- When using screw terminals, slide appropriately sized ferrules onto stranded conductors.
5. Connect the VFD Cable Ends
- At VFD end, connect the ground wire first, then power wires. Install the cable gland and tighten.
- At the motor end, terminate the cable following the manufacturer’s instructions. Torque properly.
6. Test the Terminated Cable
- Check for secure cable connections by gently pulling on each wire. Terminations should not move.
- Inspect the cable routing for proper support and minimum bend radius.
- Perform insulation resistance testing on cables to verify insulation integrity before energizing.
Following organized termination procedures ensures VFD system reliability. Tips for best results include using star washers for optimal grounding, avoiding sharp cable bends, and using correct torque specs. Taking termination care upfront prevents issues down the road.
When to Use VFD Cable
Understanding when Variable frequency drive cables are required versus when more standard options may suffice helps optimize system performance and cost. Applications where VFD cables are strongly recommended include:
New VFD Installations
Any application utilizing a new VFD should employ a matched VFD cable. The VFD cable’s shielding and electrical characteristics are designed work in harmony with the drive for trouble-free operation.
Retrofitting Existing Motors with VFDs
When retrofitting an existing motor for variable speed operation, replacing the old power cable with a dedicated VFD cable allows the system to function properly and avoid downtime.
Long Cable Runs Over 50 Feet
As motor cable run distance increases, so does the importance of Variable frequency drive cables. Their noise immunity and voltage withstand increasingly come into play. Cable runs over 50 feet between drive and motor demand VFD cables.
Motors in Electrically Noisy Areas
Applications where the motor cable route passes near large electromagnetic equipment make VFD cables indispensable to avoid interference.
Frequent Speed or Torque Changes
In applications requiring the VFD to ramp motor speed or torque up and down rapidly, Variable frequency drive cables help prevent voltage reflections through the cable that could disrupt system command response.
There are certainly applications where standard power cable may be acceptable for short VFD cable runs under 50 feet in electrically quiet environments. However, Variable frequency drive cable brings benefits like maximizing motor cable length, noise reduction, and ensured peak system performance that justify its small additional cost in most all cases.
VFD Cables from CLEF Industries
CLEF Industries offers an extensive range of Variable frequency drive cable solutions to suit any variable speed application need. As a leading supplier, top Variable frequency drive cable brands and a wide scope of options are available with excellent service.
Cable Types
- SOOW – Oil resistant VFD cable for rugged flexibility in wet areas
- TC-ER – Extreme chemical and abrasion resistant VFD cable
- Tray – VFD cable for cable trays
- Armored – Interlocked aluminum armored VFD cable
Conductor Sizes
- From 10 AWG to 500 kcmil
- Number of conductors: 3, 4, and 5
- Stranded for flexibility
Voltage Ratings
- 600V and 1000V VFD cables
- Insulation tested to 10kV
Insulation
- XLPE thermoplastic – Most common, cost effective
- EPR – Recommended for wet environments
Additional Features
- Unshielded VFD cable for shorter runs
- Different ground wire types
- Various jacket colors for phase identification
- Bulk cable spools available
Services
- Custom VFD cable sizing and terminations
- Cut VFD cable pieces in any length
- Same day shipping available
- Excellent customer and technical support
CLEF Industries stocks all major brands of VFD cable including Belden, Lapp, General Cable, and Alpha Wire. This ensures competitively priced, high performance VFD cables for any need. Bulk spools can help lower costs for larger installs.
Conclusion
VFD cables are purpose-designed for variable frequency drives, with distinct advantages that differentiate them from standard power cables. Correct Variable frequency drive cable selection, termination, and installation enables VFD systems to function as intended for maximum reliability and performance. As a top Variable frequency drive cable distributor, CLEF Industries provides all the products, services, and expertise required to keep VFD systems running smoothly. Their comprehensive Variable frequency drive cable offering delivers the ideal solution for any application need or budget.
