RVVP Flexible Shielded Cable
RVVP-300/300V
Fine-wire flexible screened cable for panel wiring, machine interfaces and short signal runs.
Screened / Shielded Control Cable
A screen does one job: it gives interference a low-impedance path to earth that does not pass through the signal conductor. How well it does that job is measured by transfer impeda
A screen does one job: it gives interference a low-impedance path to earth that does not pass through the signal conductor. How well it does that job is measured by transfer impedance, in milliohms per metre, and that figure depends on two things engineers often conflate — the optical coverage of the screen and the resistance of the path along it. Coverage governs leakage at high frequency; resistance governs behaviour at power frequency and at the switching frequencies a drive produces.
This is why the four constructions here exist side by side. RVVP is a light flexible screened cable for panel and machine wiring, LIYCY is the European equivalent with fine-wire conductors and VDE-recognised construction, KVVRP is a flexible braid-screened control cable at 450/750 V, and the overall screened twisted pair is the EMC-grade construction for panels that carry millivolt signals next to contactors.
4 constructions in Screened / Shielded Control Cable
LIYCY Braid Screened Data Cable
LIYCY-250V
The European screened data cable: fine-wire cores, tinned copper braid, VDE-recognised construction.
KVVRP Flexible Braid Screened Control Cable
KVVRP-450/750V
Class 5 conductors inside a copper braid screen, for screened circuits that move.
Overall Screened Twisted Pair Cable
OS-TP-300/500V
Foil for coverage, braid for the return path — the construction panels need next to drives.
Why must a VFD output lead be screened?
A variable frequency drive switches several hundred volts in tens of nanoseconds. That dV/dt drives a common-mode current through the parasitic capacitance between the motor conductors and earth, and the current returns to the drive through whatever path it can find — the motor earth, the cable tray, or the screen of a nearby signal cable. Left uncontrolled, it raises bearing currents and pushes radiated emissions past the limits of IEC 61800-3.
A screened motor cable gives that current a defined return path inside the cable, so it does not travel through the installation. The screen must be a braid rather than a foil, because at the carrier frequency the deciding factor is shield resistance, and it must be terminated 360° at both ends with a metal gland or a clamp.
- Use a braid screen with ≥ 85 % coverage, not a foil, on the drive output.
- Terminate the screen circumferentially at both the drive end and the motor end.
- Keep the motor earth conductor inside the same cable so the return path stays close to the phase conductors.
- Separate the motor cable from signal cable by at least 300 mm, or by a grounded steel divider.
What does screening buy on a PLC analogue run?
An unshielded 4–20 mA pair running parallel to a 400 A feeder picks up both capacitively coupled voltage and inductively coupled current. Coupled voltage divides down across the loop impedances and appears as common-mode error; coupled current flows in the loop and adds directly to the measured value. Screened cable removes the first almost entirely and reduces the second by the ratio of the shield transfer impedance to the loop impedance.
Earthing practice then decides whether the remaining error matters. Earth the pair screen at one end for a pure analogue loop so no ground-loop current circulates; earth it at both ends only where the installation has a bonded earth plane and the cable passes through an area of high-frequency interference.
- One-point earthing for 50/60 Hz analogue loops; both ends only with a bonded earth plane.
- Never use the screen as the signal return conductor.
- Keep analogue cores twisted so induced voltages remain common-mode and are rejected by the receiver.
- Route the screen drain wire to the dedicated analogue earth, not to a convenient terminal.
How do I land a screen at the panel?
The best screen is undone by a bad termination. A drain wire twisted into a pigtail adds roughly 10–20 nH, which is enough to raise the impedance of the termination path above the impedance of the interference source at a few hundred kilohertz, so the screen stops working exactly where it is needed most.
Use an EMC cable gland, a metal screen clamp on a grounded rail, or a conductive backshell on a connector, all of which hold the braid against metal around the full circumference. Strip only as much sheath as the termination needs, and keep the exposed drain wire under 25 mm.
- Circumferential contact with the gland or clamp, not a twisted pigtail.
- Bond the gland to the panel earth with a short, wide strap rather than a long wire.
- Keep the drain wire short — under 25 mm from the sheath cut to the terminal.
- Verify continuity from the screen to the panel earth bar after termination, not before pulling.
Request pricing across Screened / Shielded Control Cable
Include cross-section, core count, voltage grade, route length and installation method — those five determine price more than anything else on the page.
- Engineer-reviewed before pricing
- Reference drawings issued with the quotation
- Free sample up to free sample up to 5 m