Delta ASDA-A3 Series User Manual page 41

Installation
Installation precautions
The ferrite ring is commonly used when peripheral devices (such as the controller) are affected
2
by noise from conduction and radiation when the servo motor is in the Servo On state. The
parasitic capacitance between the cables in the wiring panel and the ground is typically small,
but as the frequency of the signal increases (Servo On state), the resistance of the parasitic
capacitance becomes small enough for the common-mode current to flow through. Normally,
common-mode current only leads to common-mode interference due to an unstable circuit
caused by a poor connection between the power circuit and ground. If the common-mode current
flows through the external cables, common-mode interference may also happen due to electrical
interference caused by unstable electric potential.
The ferrite ring causes eddy current losses to high-frequency signals and transforms them into
heat when suppressing common-mode interference. The ferrite ring acts as a low-pass filter to
effectively suppress high-frequency noise and ensure the stability of the circuit while the
impedance to low-frequency signals is relatively small.
Winding several turns of wire onto the ferrite ring can increase inductance and the ability to filter
out high-frequency noise. The suggested winding methods are shown below.
For A3-220V model (4.5 kW - 7.5 kW)
1.
For A3-220V model (11 kW - 15 kW)
2.
Note:
Refer to Section 3.1.4 for the selection of the motor power cable.
1.
Only the motor power cable or power cable can run through the ferrite ring. If needed, prepare extra
2.
ferrite rings for grounding.
An EMI filter may be required for absorbing radiation when using a longer motor power cable.
3.
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ASDA-A3