ABB ACS850 series, Hardware Manual

Page: 66 / 120

Electrical installation
66
Grounding and routing the control cables
The shields of all control cables connected to the JCU Control Unit must be
grounded at the control cable clamp plate. Use four M4 screws to fasten the plate as
shown below left (two of the screws are also used to hold the cover mounting
bracket). The plate can be fitted either at the top or bottom of the drive.
Before connecting the wires, run the cables through the cover mounting bracket as
shown in the drawing below.
The shields should be continuous as close to the terminals of the JCU as possible.
Only remove the outer jacket of the cable at the cable clamp so that the clamp
presses on the bare shield. At the terminal block, use shrink tubing or insulating tape
to contain any stray strands. The shield (especially in case of multiple shields) can
also be terminated with a lug and fastened with a screw at the clamp plate. Leave
the other end of the shield unconnected or ground it indirectly via a few nanofarads
high-frequency capacitor (e.g. 3.3 nF / 630 V). The shield can also be grounded
directly at both ends if they are
in the same ground line with no significant voltage
drop between the end points.
Keep any signal wire pairs twisted as close to the terminals as possible. Twisting the
wire with its return wire reduces disturbances caused by inductive coupling.
Re-install the cover assembly according to the instructions on page 49 .