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FBI agent , 11-18-2023, 06:13 PM

Hi everyone,
I have had an confusion while I was working on the Class-X and Class-Y capacitors. Is there anyone who can check my information whether true ? By the way, i wonder some question's answer and i putted them below. I'm waiting for the response of you. Thanks in advance.

**Questions : **
1-) Should i use them for DC input line ? (Or Bulk capacitors at the circuit's input work like Class-X capacitors ?)
2-) How should be the value of these capacitors ? (it depends on the requirements what you are taking as reference Like IEC standarts ?)
3-) For using the Class-Y capacitor, If the user doesn't connect the earth line to device, What will happen ? It is not our problem ?

**My Information about Class-X and Class-Y :**
-> Class-X Capacitors:
We are using them to mitigate the common mode noise that comes from input. The Class-X capacitors must be short circuit to cut the line current by using fuse If the some failure occurs. These capacitors are required to place between the lines. (That's all. Is there anything else external ? )

-> Class-Y Capacitors :
We are using them to mitigate the differential mode noise that comes from input. The Class-Y capacitors must be open circuit to cut the line current to protect humans from electrical shock If the some failure occurs. These capacitors are required to place between the line and earth. (That's all. Is there anything else external ? )

Robert Feranec , 11-19-2023, 02:12 PM

Maybe this can help a little bit? https://www.youtube.com/watch?v=fkNa-FejWsQ&t=2784s

FBI agent , 11-19-2023, 05:31 PM

Thanks Mr. Robert. I'm gonna take a look this video. Thanks for your support. 😊

QDrives , 11-19-2023, 09:22 PM

Are you talking about AC mains input or low voltage DC?
X and Y capacitors are for safety in mains powered input circuits. X capacitors are between lines and/or neutral. Y capacitors between line and PE. An internal 'short' will burn out that part of the capacitor so that the short is 'removed'.
IEC 60335 states a maximum leakage current of 5mA allowed when testing the device at 2.5KV (assuming 230Vac powered appliance).
For low voltage DC input devices the question is: what would happen if the capacitors fail in a short?
By the way, X is for differential mode noise and Y is for common mode.
https://www.kemet.com/content/dam/kemet/lightning/documents/ec-content/EMI-Suppression-Capacitors-Product-Selection-Guide.pdf

Dario Fresu⚡ , 11-25-2023, 05:07 PM

"3-) For using the Class-Y capacitor, If the user doesn't connect the earth line to device, What will happen ? It is not our problem ? "

Make sure you specify on the product and user manual regarding the need for connection to the Protective Earth. The user has to be aware of the dangers if this is not connected. Not only for their safety but also to protect your liability.