How to select an industrial servo input EMI filter?

The selection of servo input EMI filters must be based on measured interference spectrum, rated current, and safety requirements. The selection process by Etymotic is as follows: First, measure the conducted interference curve without a filter to determine the frequency exceeding the standard. For differential mode exceedances in the 150kHz-1MHz low-frequency band, select a combination of X2 capacitors (0.1-1μF/305VAC) and differential mode inductors (such as PWR6045R4R7M0T, 4.7μH); for common mode exceedances in the 1MHz-30MHz range, select CMZ series common mode inductors (such as CMZ7060A-701T, 70μH). The rated current should be selected as 1.5 times the servo's rated input current to ensure the inductor does not overheat. Regarding safety, the filter must meet IEC/UL 60950-1, and the X/Y capacitors must obtain the corresponding certifications. An integrated solution can be selected using a filter module with a built-in PBZ3216E-120Z0T ferrite bead. After selection and verification, the insertion loss should be greater than 10dB at the frequency point exceeding the standard, and the leakage current of the filter should meet the safety limit (usually <3.5mA).