Not once the strong electromagnetic noises have been the main cause of very hard to detect system malfunctions. That is why these noises needs to be reduced as much as possible. Below are presented some basic steps to reduce the electromagnetic noise.
1) Use shielded cables between motor
and drive and connect the shield to the drive GND terminal.
If possible, connect
the shield to motor chassis too.
2) Always have the motor chassis in
electrical contact with the machine chassis and connect the
protective earth to the machine chassis.
3) The motor voltage supply
should be floating (i.e. no connection between supply negative
wire and machine chassis because this connection will be realized
through the shield of the motor wires, at each controller).
4) Pass the motor cable
through a ferrite ring / ferrite clamp, located as close as possible to the
controller. It is advisable to make multiple turns of the cable
inside the ferrite ring.
5) Use a twisted + shielded
cable for "+Vmot" and "GND" (between controllers and supply).
6) Add an electrolytic capacitor
between "+Vmot" and "GND", as close as possible to the controller or increase the
existing capacitors. A good starting point is 10,000 uF rated at an appropriate voltage.
7) Insert an EMC line
filter on the motor supply lines, located near the
controller(s), and make sure to fix the EMC filter metallic
case to the machine chassis. Try also a filter at the input
of the motor supply (on 110/230/400VAC lines).
8) Route the motor cables
and the supply cables inside metallic structural elements
(metallic cable ducts/trays/conduits), and position these
cables near the corner of the duct cross-section. Of course,
the metallic ducts must be connected to machine chassis
using large contact surfaces (make sure paint doesn’t block
contact).
9) If controllers are inside a
cabinet / box, make sure both the walls and the door are
connected to machine chassis (use copper braid grounding
straps to connect doors near hinges).
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