In EV and storage systems, HV harnesses run next to low-voltage signal lines. Fast PWM switching radiates interference; poor shielding fails EMC. Here is how to choose among three mainstream shield structures.
1. Aluminum foil: the value choice
Foil shields block high-frequency E-fields well at low cost and stay flexible, but are mechanically weak — usually paired with a drain wire for continuity.
2. Braid: shielding plus mechanical strength
Tinned-copper braid (85-95% coverage) adds low-frequency magnetic shielding and mechanical strength for vibrating on-board HV runs, at 2-4x cost. Recommended on the interference-source side of HV circuits.
3. Foil + braid combo: for tough EMC
Foil plus braid covers the full spectrum and is standard for automotive HV harnesses facing limits like CISPR 25.
4. Three commonly missed points
Ground single-ended vs both ends by interference type; keep 360° shield termination at connector shells; and route HV away from signal lines — physical distance is the cheapest shield.
Final words
Shielding is about the lowest-cost structure that passes your EMC limits. Send us your system targets: +86 184 0755 1752 / eric@muyenda.com.