Helukabel TOPFLEX-EMV-3-PLUS Screened VFD Motor Cable

The Helukabel TOPFLEX-EMV-3-PLUS-2YSLCY-J is a double-screened motor connection cable for frequency converters. The earth conductor is split into three green-yellow cores laid symmetrically in the gaps between the three phase cores, a 3+3 construction that Helukabel describes as giving better EMC properties than a conventional four-core layout. A plastic-coated aluminium foil and a tinned-copper braid of about 85 percent coverage sit under a transparent special-PVC sheath, so the core colours stay visible.

Technical specifications

Why the split earth construction matters on a drive

Helukabel describes the optimal screening as enabling interference-free operation of frequency converters, and the low coupling resistance as giving good electromagnetic compatibility. The PE core insulation and low screen capacitance keep the capacitance of the individual cores small, which supports low-loss power transmission. Three symmetrical protective cores carry fault and high-frequency earth currents back to the drive with lower impedance than a single earth conductor.

The data sheet specifies it as a connecting cable for medium mechanical stress with fixed installation and occasional free movement, in dry, damp or wet rooms, not outdoors, and names the automotive, food, packaging and chemical industries and environmental technology as typical sectors. For outdoor routes use the UV-resistant TOPFLEX-EMV-UV types. For continuous chain or robot flexing, use the PUR TOPFLEX 611-C-PUR instead.

Sizes and current-carrying capacity

* Current carrying capacity with three loaded cores, for continuous operation up to 30 °C ambient temperature; for other ambient temperatures apply the conversion factors of DIN VDE 0298-4 (as printed on the data sheet). The coupling resistance per size is also listed in the data sheet table. Sizes in the range go up to 3 x 240 + 3 G 42.5 mm².

Where a screened VFD motor cable makes the difference

A frequency converter does not feed the motor with a clean sine wave. Its output switches at high frequency with steep voltage edges, and an unscreened cable between drive and motor acts as an antenna. The result can be interference on nearby instrument and communication cables, unexplained PLC faults, false readings on analogue signals and high-frequency currents flowing through motor bearings. A double screen of foil plus tinned-copper braid, combined with the symmetrical 3+3 core layout, keeps those currents in a defined return path back to the drive.

Choosing the cross-section

Size the phase conductors from the motor current, the installation method, the ambient temperature and the permitted voltage drop over the route, then check the result against the drive manufacturer’s recommended cable. Helukabel’s current-carrying tables apply to stated reference conditions; grouping several cables on one tray or running them in hot plant rooms requires correction factors. Remember that the maximum permitted motor cable length is set by the drive, not by the cable alone.

Installation practice

• 360° screen termination: clamp the braid all the way round in EMC glands at both the drive and the motor terminal box. Twisted “pigtails” defeat much of the screening effect at high frequencies.
• Protective cores: connect all three green-yellow cores together at each end so the split earth works as intended.
• Separation: keep motor cables apart from signal and fieldbus cables, and cross them at right angles.
• Bending: respect the minimum bending radius given above, both during pulling and in the final route; the foil screen can tear if the cable is kinked.
• Flexible or fixed: the lower temperature limit is different for flexible and fixed laying, so check which applies to the installation.

Transparent sheath advantages

Because the outer sheath is transparent, an inspector can see the braid and identify core colours without stripping the cable. Damage to the screen from a crushed tray or a sharp edge is also easier to spot during maintenance rounds.

Applications in Oman and the GCC

Drives for pumps, HVAC fans, compressors, conveyors and cranes are widely used in water utilities, desalination, district cooling, cement and mining operations in the region. Long cable routes between motor control centres and field motors, and dense cable trays near instrumentation, are where EMC problems usually appear. The PVC sheath is intended for indoor and protected routes; for direct sun on exposed outdoor trays, consider UV-protected routing or ask for a suitably rated alternative from the Helukabel range.

RFQ information

• Cable type TOPFLEX-EMV-3-PLUS-2YSLCY-J and the number of cores and cross-section.
• Total length and drum lengths required.
• Matching EMC cable glands, if needed.
• Drive model and motor rating for cross-checking.
• Delivery site and requested date.

Documents and quotation

The Helukabel data sheet (05.06.2024) is attached. Seven Star LLC supplies Helukabel cables in Oman against the part number. Confirm the drive power, motor current, cable length, whether the route is fixed or moving, and the screen termination hardware (EMC glands) before ordering. See related cable accessories.