I have been given the following circuit:
The input of this circuit is a 3.3 kV DC signal. The filter is there to stabilize high frequency ripples that might appear on the supply line.
As far as I can see, this is a 3rd order low pass filter (R11/C11 + R14/C12 + R15/C13...not sure about the last one, though, since C13 is smaller).
What I don't understand:
1) the function and values of the resistors in the "return" line (R12, R13, R16).
2) Isn't this return line supposed to be just ground? Any particular reason why they would call it "return"?
Final note: my assumption is that J5 is used to monitor the current through R16 (to, conversely, monitor the HV value) but I am not 100% positive on this.