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Y cap values are high (33nF)?

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cupoftea

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Hi,
We just looked at a customer product, and it was a offline Power supply, with PFC.
The mains input filter, was two common mode chokes (presumably with leakage inductance). These had 2.2uF X2 caps either side of them. Also, there are four Y caps…which are all 33nF in value.
The common mode chokes are marked up as “630uH".
How common are such large Y capacitor values? There’s going to be about 5mA of imbalance current …so not at the 27mA RCD trip level but high nonetheless.
 

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Some very large industrial equipment is "allowed" higher value EMC caps - as and where the earth bonding back to the supply transformer is very low impedance,

However - for a common garden psu, anything over 10nF - Industrial

or 4n7 commercial - is not within stanfards for 230Vac 50/60Hz

you neglected to say where they were made ? china spain bangladesh india ....
 
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