Project requirements · Mechanical
EMC, screening effectiveness
A screen limits emission and pick-up, e.g. for VFD motor cables and instrument cables.
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Constructions that meet it
- Tinned copper braid: changes the cable's layers. Tinned copper braid at a given optical coverage (tinned Cu). Drawbacks: Weight, cost; termination quality decides real performance.
- Aluminium foil plus copper braid: changes the cable's layers. Aluminium / polyester foil plus braid (Al foil + Cu braid).
- Concentric copper wire screen: changes the cable's layers. Concentric copper wire screen (symmetric VFD cables, 3+3 earth) (Cu).
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Tests
- IEC 62153-4-3:2013 + A1:2024: surface transfer impedance, triaxial method. Pass: maker value, e.g. Lapp ÖLFLEX SERVO FD zeroCM max. 250 mΩ/m at 30 MHz
- Coupling resistance (Helukabel TOPFLEX-EMV): maker method. Pass: max. 250 Ω/km, by cross-section
- EN 50173 (data cabling): transfer impedance limits. Pass: 50 mΩ/m at 1 MHz, 100 mΩ/m at 10 MHz (secondary)
How specifications state it
Often only 'screened, braid coverage ≥ 85 %'; better specifications give transfer impedance at a frequency.
Where it is asked for
- VFD motor cables
- instrumentation
- data and control in industrial plants
Sources
- IEC 62153-4-3:2013+AMD1:2024 CSV listing (AFNOR) (quoted by others)
- Lapp ÖLFLEX SERVO FD zeroCM DB1023470EN v02 (transfer impedance at 30 MHz max. 250 mΩ/m), Conrad copy (quoted by others)
- Helukabel TOPFLEX-MOTOR-EMV 103 datasheet M78614 (coupling resistance max. 250 Ohm/km) (quoted by others)