What are the differences between an ordinary and "class-X2" MKP capacitors?

[powersys]

I wish to choose a metallised polypropylene (MKP) capacitor (0.1uF or 2.2uF) for C5 shown in attached figure below. I came across the following choices:

[1] VISHAY BC COMPONENTS - BFC233620104 - CAPACITOR, CLASS X2, 0.1UF
VISHAY BC COMPONENTS|BFC233620104|CAPACITOR, CLASS X2, 0.1UF | Farnell

[2] EPCOS - B32922C3104M - CAPACITOR, CLASS X2, 0.10UF, 305VAC
EPCOS|B32922C3104M|CAPACITOR, CLASS X2, 0.10UF, 305VAC | Farnell

[3] EPCOS - B32652A6104J - CAPACITOR, 0.1UF, 630V
EPCOS|B32652A6104J|CAPACITOR, 0.1UF, 630V | Farnell

All of them have similar AC and DC voltage ratings. They are constructed from the same dielectric material i.e. polypropylene. However, items [1] and [2] are labelled as "Class-X2". What are the features that make [1] & [2] but not [3] labelled as "Class-X2"? Can items [1], [2] and [3] be used as R5 in the power inverter (VDC=150V, Q1~Q6 are power MOSFET, maximum PWM frequency 10kHz, C1~C4 are aluminium electrolytic capacitors) shown in the figure below?

Cheers.

 

[audiomik]

Re: What are the differences between an ordinary and "class-X2" MKP capacitors?

Class X2 Capacitor types are designed for use primarily in Mains filters.
Datasheets on some here: "class x2" capacitor "0.15" datasheets and application notes, data sheet, circuit, pdf, cross reference, pinout, datasheet | Datasheets.org.uk

hope this assists
Mik

 

[powersys]

Re: What are the differences between an ordinary and "class-X2" MKP capacitors?

Thank you audiomik. If both MKP capacitor [1] and [3] have similar AC/DC voltage ratings, is it true to say that X2 rated MKP capacitor can be safely used to replace any non-rated MKP capacitor but not the other way around?

Cheers.

 

[audiomik]

Re: What are the differences between an ordinary and "class-X2" MKP capacitors?

Basically yes, wouldn't use 'non X' types for mains filtering as they don't have the insulation or 'self healing' properties needed for safe Mains filtering.
Some other parameters can apply - especially relating to things like series inductance which might be something you should look at with a mind towards their impedance characteristics, which can depend on the construction of the capacitors themselves.
Mik