Below are the questions asked during the live event, along with their respective answers.
Q: Chokes present only on phase and neutral fail to suppress noise that leaves the source on the equipment ground (the “green wire”) due to improper termination of the green wire within the noise source equipment.
A: The presentation is based on general common mode chokes used to mitigate conducted emissions on power lines. In cases where the ground wire requires to be filtered a three winding CM should could be used.
Q: To suppress noise current on the equipment ground conductor, all three conductors (phase, neutral, and ground) must pass through the choke. A choke that does not include the “green wire” simply does not work. The conducted noise on the green wire radiates, is often the dominant source of emissions below VHF, and is the dominant mechanism at HF and MF. Suitable chokes can be built by winding multiple turns of the cable carrying the noise through a suitable ferrite toroid or clamp-on.
A: You are correct, in cases similar to the one you mentioned where radiated emission is a problem using a ferrite bead over the whole cable including the ground wire is most helpful.
Q: Slide 17, the multilayer shows the higher capacitance, but the impedance graph is not consistent with the results shown in the slide 16. Could you make some comments here, as I may be missing something?
A: Good observation, the difference that you have noticed is the parasitic component values measured by conventional LCR meter which might not be accurate enough to measure such low value capacitance and inductance. We believe the analyzer measurements are more accurate.
Q: On the slide 24 did you consider the tolerances of the cores?
A: Yes we did. The cores used were from the same manufacturing lot and both mechanical and core technical parameter were within the data sheet given by manufacturer’s data sheet.