How can industrial servo X/Y capacitors balance EMC and safety regulations?

In servo systems, X capacitors (line-to-line) and Y capacitors (line-to-ground) are critical filtering components. Their selection must simultaneously meet EMC filtering performance and safety insulation requirements. Audiotech's design principles are as follows: X capacitors are primarily used to attenuate differential-mode noise. Their capacitance value is selected based on the frequency exceeding the standard (0.1μF-2.2μF), and they must be X2 certified (e.g., 310VAC) with a discharge resistor (ensuring voltage drops to a safe value within 1 second). Y capacitors provide a return path for common-mode noise, and their capacitance value should be small (typically 1nF-4.7nF) to control leakage current to ground (<3.5mA per line). Y1 or Y2 safety certified capacitors (e.g., 250VAC) must be selected. In terms of layout, Y capacitors should be connected as close as possible between the interference source (e.g., IGBT heatsink) and the chassis ground, with the connection wire as short as possible. With optimization, the X/Y capacitor combination can increase the conducted interference limit margin by 6-10dB, while also passing the IEC 60335-1 safety standard for household and similar appliances.