ABB ACS150 User Manual page 24

24
Motor cable shield
To function as a protective conductor, the shield must have the same cross-sectional
area as the phase conductors when they are made of the same metal.
To effectively suppress radiated and conducted radio-frequency emissions, the
shield conductivity must be at least 1/10 of the phase conductor conductivity. The
requirements are easily met with a copper or aluminium shield. The minimum
requirement of the motor cable shield of the drive is shown below. It consists of a
concentric layer of copper wires with an open helix of copper tape. The better and
tighter the shield, the lower the emission level and bearing currents.
Additional US requirements
Type MC continuous corrugated aluminium armor cable with symmetrical grounds or
shielded power cable is recommended for the motor cables if metallic conduit is not
used.
The power cables must be rated for 75°C (167°F).
Conduit
Where conduits must be coupled together, bridge the joint with a ground conductor
bonded to the conduit on each side of the joint. Bond the conduits also to the drive
enclosure. Use separate conduits for input power, motor, brake resistors and control
wiring. Do not run motor wiring from more than one drive in the same conduit.
Armored cable / shielded power cable
Six-conductor (three phases and three ground) type MC continuous corrugated
aluminium armor cable with symmetrical grounds is available from the following
suppliers (trade names in parentheses):
• Anixter Wire & Cable (Philsheath)
• BICC General Corp (Philsheath)
• Rockbestos Co. (Gardex)
• Oaknite (CLX).
Shielded power cables are available from Belden, LAPPKABEL (ÖLFLEX) and
Pirelli.
Planning electrical installation
Insulation jacket Copper wire screen Helix of copper tape Inner insulation
Cable core