Variable-frequency drive cable · shielded motor cable
VFD cable buyers in New York
Drive cable is the one power cable whose value depends on a shield you cannot see from the outside. A reel can look perfect and be worthless, because the foil inside has broken somewhere between the two ends.
Sell this cable
Send the construction, size and footage. Photographs can follow.
Prefer to talk? 614-715-3047 · saleselectricalbuyers@gmail.com
VFD cable is reviewed on conductor size, ground configuration, voltage rating, shield construction and shield continuity. Three symmetrical grounds and an intact foil-plus-braid shield are what make it drive cable. A 1 kV, 4 AWG, three-ground cable with a continuous shield is a stock item; the same cable with a broken shield is ordinary flexible power cable.
Three conductors and three grounds, symmetrically arranged
A drive cable carries the pulse-width-modulated output of a variable-frequency drive to a motor. It is a three-conductor power cable, but almost everything else about it is different from ordinary tray cable. The three ground conductors are the most obvious sign: instead of one ground in a corner of the assembly, a drive cable places a bare copper ground in each of the three interstices between the power conductors, so the grounds sit symmetrically around the core.
That symmetry is not decoration. At the switching frequencies a drive produces, current does not simply follow the path of least resistance; it follows the path of least impedance, and it will return through whatever conductor and capacitance is nearest. Three evenly spaced grounds give the return current a short, balanced path and stop it from diverting into the motor shaft, the bearings, the encoder cable or the building steel. The result is lower common-mode current, fewer bearing currents and a quieter installation.
The power conductors themselves are stranded copper, sized from 16 AWG on small integrator panels up to 500 kcmil on large process drives. Insulation is XLPE at 90°C, with phases identified by color or number. The whole assembly is bound, shielded and jacketed, and the jacket is usually printed as tray cable so it can run exposed from a tray down to the motor.
Why drive cable is often rated 1 kV
A drive output is not a sine wave. It is a train of fast-rising pulses, and when those pulses travel down a long motor lead they reflect at the motor terminals. The reflected wave can roughly double the DC bus voltage, and on a 480 V system with a long run that puts peak stress well above what a 600 V cable was ever designed to absorb. A 1 kV rating exists for that condition.
The practical rule in plant engineering is that short leads on a 480 V system can use 600 V cable, while long leads, 600 V systems and anything where the drive manufacturer specifies a higher rating use 1 kV. Because the run length is not knowable at the reel, much of the drive cable sold in New York is 1 kV, and that rating is a real part of what a buyer is paying for.
The rating appears in the jacket print and it does not change with age. A 1 kV reel that has been in a hot motor control room for a decade is still a 1 kV reel if the jacket and insulation are intact — which is why footage and storage matter more here than on, say, building wire.
Shield integrity is the resale argument
The shield in a drive cable has two jobs: keep the drive's high-frequency noise inside the cable, and give the return current a defined path back to the drive. Both jobs depend on the shield being electrically continuous from one end to the other and being terminated with a full 360-degree connection at the gland or the drive enclosure. A pigtail drain wire connected to one screw is a poor termination at these frequencies, but it is still far better than a broken shield.
Foil shields break in predictable ways. A cable bent tighter than its radius creases the tape; a cable pulled hard around a corner tears it; a cable whose jacket has been cut during a termination has probably cut the foil beneath. Braid shields survive abuse better but can be pulled back, corroded or cut. Once the shield is broken, the cable is no longer drive cable: it will radiate, it may cause nuisance trips on the drive, and no amount of careful installation will restore it.
That is why the first thing to establish on any drive cable lot is continuity, end to end, from the shield at one end to the shield at the other. It takes an ohmmeter and two people. A reel with a continuous shield and clean jacket is reusable; a reel that fails is sold as flexible power cable or as copper, and should be described that way rather than discovered on site.
What New York drive work leaves behind
Drives are now standard on pumps, fans, compressors, conveyors, mixers and almost anything else with a motor, because utilities and energy codes push variable speed as the cheapest way to cut consumption. New York's water and wastewater plants, food and dairy processors, paper mills, quarries, hospitals and large commercial central plants all run drive cable in quantity, and each replacement motor or drive leaves a length of it behind.
The usual lot is not a full reel. It is a 40 to 120 ft length cut out when a motor was changed, with the shield cut back at both ends and the jacket stripped. Those lengths are reviewed on usable footage between the cut ends, whether the shield survived the cut-back, and whether the ground conductors are still full length. Full reels do appear when a project changes drive locations or when a panel shop over-orders, and those are the lots worth moving quickly.
- Conductor size and number of ground conductors — three is the drive standard
- Voltage rating, 600 V or 1 kV, from the jacket print
- Shield construction, and whether continuity has been tested end to end
- Usable length between cut ends on removed cable
- Jacket condition, especially crush marks and cuts near the ends
Specification
What a buyer needs to know about this cable
Every row below changes what a lot is worth. If the reel tag is gone, the jacket print and a cut end usually answer most of it.
Missing detail is not a problem — say what is missing and the review works from photographs.
| Conductors | Three power conductors, Class B or Class K stranded copper, 16 AWG through 500 kcmil |
|---|---|
| Grounds | Three bare copper ground conductors, one in each interstice, symmetrical around the core |
| Voltage rating | 600 V or 1,000 V; 1 kV is standard where motor leads are long or the system is 600 V |
| Insulation | XLPE, 90°C, with phase identification by color or printed number |
| Shield | Aluminum-polyester foil with 100 percent coverage plus a tinned copper braid, or foil with a drain wire |
| Jacket | PVC, CPE or polyurethane, oil resistant and sunlight resistant; TC-ER listing is common |
| Size range | 16, 14, 12, 10, 8, 6, 4, 2, 1/0 through 500 kcmil; 8 to 2 AWG dominate plant work |
| Condition signals | Shield continuity end to end, jacket cuts, flattened reel wraps, water in the core, missing grounds |
Constructions
Drive cable we review
The size sets the buyer, but the shield decides whether there is a buyer.
Small drive cable, 16–10 AWG
Panel and small motor work, often 600 V with a foil shield and drain. Common in integrator stock and in packaged equipment. Reviewed on footage and shield integrity.
Mid-size, 8–2 AWG
The plant workhorse for pumps, fans and compressors. Usually 1 kV, three grounds, foil plus braid. Whole reels and long cut lengths are both worth reviewing.
Large drive cable, 1/0–500 kcmil
Process and utility drives on long leads. Heavy, stiff and expensive to freight, so the footage and the loading access matter as much as the size.
1 kV shielded constructions
Rated for reflected-wave stress on long motor leads. The rating on the jacket is a genuine premium over 600 V material.
Cut lengths from motor changes
Field lengths with the shield cut back at both ends. Reviewed on usable length, ground continuity and whether the cut-back left enough jacket to re-terminate.
Unshielded flexible power cable
Often sold as drive cable but built without a shield. It is a legitimate product for VFD output only where the drive manufacturer permits it, and it is valued as ordinary flexible cable.
New York
VFD cable in the New York market
Demand tracks the state's pumping and process base. Water and wastewater utilities, food and beverage plants, paper mills, quarries and large institutional central plants all keep drive cable in stores, and they buy it in the sizes their motors use rather than in one standard size. That makes the market for any given reel narrow and specific, which is why an accurate size and shield description matters more than a large lot.
Supply arrives in small increments. A drive upgrade releases the old cable; a motor replacement releases a field length; a panel shop closes out a project with part reels. Because the quantities are modest, drive cable is one of the families where several small lots from the same region are worth combining into a single review.
What helps a New York lot move
- AWG and number of power conductors
- Ground configuration — three symmetrical grounds is the drive standard
- Voltage rating from the print, not from memory
- Shield type, and confirmation of end-to-end continuity
- Footage, and for removed cable the usable length between cuts
Seller questions
Questions sellers ask
Why does VFD cable have three ground conductors?
Because the drive's output current returns at high frequency, and symmetry controls where it flows. Three grounds placed evenly around the core give a short, balanced return path, which reduces common-mode current, shaft voltage and bearing damage. A single ground in one corner of the cable leaves an unbalanced path and is one of the reasons ordinary power cable performs poorly on drive duty.
How can I tell whether the shield is intact?
With an ohmmeter, end to end, between the shield at one end and the shield at the other. A continuous reading means the foil or braid has survived. Any open circuit means the cable has lost the property that made it drive cable. Visual inspection helps but is not conclusive, because foil can break inside an intact jacket.
Do you buy 600 V drive cable as well as 1 kV?
Yes. Both ratings are bought, and the rating is established from the jacket print. A 600 V cable suits short motor leads on a 480 V system where the drive manufacturer permits it; 1 kV is used for longer leads and for 600 V systems. The rating is a value factor, not a pass or fail.
Is unshielded cable ever acceptable for a drive?
Sometimes, and only where the drive manufacturer says so, usually on very short leads inside a single enclosure. It is a different product from shielded drive cable and should not be described as VFD cable without that qualification. Most plants specify shielded cable because the noise problem is expensive to diagnose later.
What lengths are worth collecting?
A full or part reel with confirmed footage always justifies a look. Field lengths are worth reviewing from roughly 40 ft upward in the mid sizes, because a motor change often leaves enough to serve another motor. Short offcuts below that are usually copper value unless they are large conductor.
Keep reading
Related pages
- Control cable buyersThe cable that runs alongside drive circuits
- Instrumentation cable buyersTwisted-pair cable shielded against drive noise
- Tray cable buyersTC and TC-ER assemblies
- Feeder cable buyersThe supply side of the drive
- Plant liquidation cable buyersProcess plant drive and motor stock
- Copper wire buyersCopper conductor and its value
Next step
Send the lot details
Include the storage city, how it is stored and what can reach it. If you have photographs of reel tags or jacket print, send them with the enquiry.
Send the lot
One desk reviews every lot that arrives.
Prefer to talk? 614-715-3047 · saleselectricalbuyers@gmail.com