Delta ASD-A2-0121 Series User Manual page 45

ASDA-A2 Chapter 2 Installation
Installation precautions
The ferrite ring is commonly used when peripheral devices (such as a controller) are affected 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. As the
frequency of the signal increases (Servo On state), the resistance of the parasitic capacitance
becomes small enough to let common-mode current 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 a high-frequency signal and transforms it 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:
1. For A2-220V model (4.5 kW ~ 7.5 kW) and A2-400V model (2 kW ~ 7.5 W)
2-6