In power electronics devices and systems, safety capacitors are essential electronic components used to filter out interference on power and signal lines, protecting equipment and systems from the impact of electromagnetic interference. In electronic circuits, it is common to find one X capacitor accompanied by two Y capacitors.
Why is there a need for two Y capacitors around one X capacitor in a circuit?
Safety capacitors are electronic components that have obtained safety certification through safety testing. They are used to protect circuits and ensure the personal safety of users. Safety capacitors are divided into two categories: X capacitors and Y capacitors.
X capacitors are connected across the neutral and live lines, with a larger capacitance in the microfarad (uF) range. They primarily filter out common-mode interference signals. Y capacitors, on the other hand, are connected between the live and ground lines and between the neutral and ground lines, with a smaller capacitance in the nanofarad (nF) range. They mainly filter out differential-mode interference signals.
The reason for one X capacitor being accompanied by two Y capacitors in a circuit is as follows:
Differential-mode interference is a type of interference that occurs simultaneously on both power lines or signal lines. Because it has equal amplitude and phase, a single X capacitor is sufficient to filter out differential-mode interference.
Common-mode interference, on the other hand, is a type of interference that occurs simultaneously on the neutral line, live line, and ground line. Since common-mode interference has different amplitudes and phases, especially with larger interference on the ground line, it cannot be effectively filtered out by the X capacitor alone. Therefore, two Y capacitors are used, each connected across two different ground lines, to effectively filter out common-mode interference.
This explains why it is common to see one X capacitor accompanied by two Y capacitors in electronic circuits. Additionally, this configuration can enhance the stability of the system. Due to the different functions of X and Y capacitors, their distribution on power lines varies. The configuration of one X capacitor with two Y capacitors helps balance the distribution on power lines, reducing potential differences between them and improving system stability.
This article is provided by JYH HSU Electronics, a manufacturer of electronic components such as capacitors and resistors.
Post time: Nov-14-2023