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microman • Aug 25, 2006

Suppression capacitors

Anyone out there can help me on this issue!
Two capacitors in a power supply board for a oscillioscope emiited smoke and by the time i took out the caps, they were cooked "medium rare". Both the caps were of the the same cap value as follows.

0.068 uf X 2 , 250V.

Can i replace them with a normal cap , with ratings of the same voltage. Would it work? What does the " X2" stands for.

Joy to U.....
Kaustubh Katdare
Kaustubh Katdare • Aug 25, 2006
*bump*, Your engineering trade is 'micky mouse' 😒 ? Assuming that you are an electrical engineer, I edited your profile and changed it to 'electrical'. Make appropriate changes.
-The Big K-
pradypop • Aug 25, 2006

The capacitors that filter out interference from the AC power are called Suppression Capacitors.
There are two major types of suppression / AC line filter safety capacitors; namely, type X and type Y. The purpose of these capacitors is to reduce radio frequency interference and to ensure safety from shock and fire.

Class X capacitors are used in “across-the-line” applications where their failure would not lead to electric shock. Class X safety caps are used between the “live” wires carrying the incoming AC current. In this position, a capacitor failure should not cause any electrical shock hazards, rather, a capacitor failure “between-the-lines” would usually cause a fuse or circuit breaker to open.

Class Y capacitors are used in “line-to-ground” (line bypass) applications where their failure could lead to electric shock if a proper ground connection were lost. The failure of a “line-to-ground” capacitor would not open any safety fuse. In other words, the failure of a line bypass capacitor could create a 120 volt “hot” chassis that could give you a potentially fatal shock.

Safety capacitors are grouped into a number of different classes. For X Type capacitors there are class X1, X2 and X3. For Y Type capacitors there is class Y1, Y2, Y3 and Y4.
The only types you will probably see for sale are X1 (impulse tested to 4000 Volts), X2 (tested to 2500 V), Y1 (tested to 8000 V) and Y2 (tested to 5000 V).

Normal capacitors can ensure that your device is functional but will not provide any protection from shock or interference.

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