ABB ACS800-67LC, Hardware Manual

Page: 57 / 154

Planning the electrical installation 57

Rotor cable shield
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 rotor
cable shield of the converter 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 the bearing currents.

Additional US requirements
Type MC continuous corrugated aluminum armor cable with symmetrical grounds or
shielded power cable must be used for the generator cables if metallic conduit is not used.
For North America, 600 V AC cable is accepted up to 500 V AC. 1000 V AC cable is
required above 500 V AC (below 600 V AC). For converters rated over 100 A, the power
cables must be rated for 75 °C (167 °F).
Insulation jacket
Copper wire screen
Helix of copper tape
Cable core
Inner insulation
U2 V2 W2
PE
Converter
U2 V2 W2
PE
Converter
K
L
M
PE
G
3 ~
L1
L3
L2
Concentric Al/Cu shield
Single core cable, shielded or
unshielded
Site main
earth bus of
the wind
turbine
Site main
earth bus of
the wind
turbine
PE
K
L
M
G
3 ~
Separate protective
conductor
A separate PE conductor system is used
only if local safety regulations do not
allow earthing of the converter and the
generator merely through the cable
screen. This solution increases bearing
currents compared to symmetrical
shielded cable, thus causing extra wear.
U2 V2 W2
PE
Converter
Galvanised steel or
copper armour
Separate protective
conductor
Site main earth bus
of the wind turbine
PE
K
L
M
G
3 ~