Hello , I am studying about capacitor's names and I am stuck with a capacitor named 2K7J400 . Does it means that it is 2.7kF with +-(5%) up to 400 Volts . And what is happening if a capacitor has a name like 103 ?
Thanks for your help ! Sorry for my bad English .

 

A capacitor that big would be about the size of a house. Would be best to post a picture, it then may be easier to decode the marking.

 

Each manufacture uses their own part-naming convention, so the only sure way is to figure out who the manufacturer is and look at their nomenclature description (assuming they make it available). If you look at their catalog, you can sometimes figure at least most of it out. Anything beyond that is guessing, but some guesses are more reasonable than others.

The K might be the radix point, but it is NOT indicating kilofarads!

Generally something like 103 would mean 10000 (all but the last digit followed by the number of zeroes indicated by the last digit). Depending on the part, the units might be pF or uF or whatever the manufacturer decided was reasonable for their part line.

 

A capacitor that big would be about the size of a house. Would be best to post a picture, it then may be easier to decode the marking.

oh I don't have a specific picture , actually my professor gave me some capacitor's names and he told me to find the value of them . So that's it .

 

Each manufacture uses their own part-naming convention, so the only sure way is to figure out who the manufacturer is and look at their nomenclature description (assuming they make it available). If you look at their catalog, you can sometimes figure at least most of it out. Anything beyond that is guessing, but some guesses are more reasonable than others.

The K might be the radix point, but it is NOT indicating kilofarads!

Generally something like 103 would mean 10000 (all but the last digit followed by the number of zeroes indicated by the last digit). Depending on the part, the units might be pF or uF or whatever the manufacturer decided was reasonable for their part line.

Thanks for your reply !

 

oh I don't have a specific picture , actually my professor gave me some capacitor's names and he told me to find the value of them . So that's it .

Depending on how much practical experience your prof has, he may actually think that there is a standard naming convention based on seeing one manufacturer's convention. But this just isn't the case.

 

I've seen a lot of different capacitors in my decades in electronics and have never seen one marked that way. A marking like 2n7 or 2u7, meaning 2.7 nF and 2.7 µF is common. I would take 2k7 to mean 2.7k picofarads = 2.7 thousand picofarads.. 2n7J400 is the marking I would expect.

J is standard for ±5% tolerance and 400 would normally be the DC voltage rating.

Sometimes you see voltage marked
~400
which would mean 400 VAC RMS

Sometimes you see a solid bar above a dashed line like
___
-----
in front of a voltage rating, which normally means the rating is DC volts

Sometimes you will see both a DC voltage rating and an AC voltage rating marked, but this isn't very common.

It has become very common to see capacitors marked in picofards as digit-digit-multiplier, so 103 would mean 10 x 10^3 picofarads. The marking method has the advantage that it covers 10 decades, from 100 (10 picofarads) to 999 (99 000 microfarads) with 3 characters, though it is rare to find it used above about 100 µF. This method isn't as common for capacitors that are physically large and there is room for other marking styles. But as WBahn says, different manufacturers do things differently. Sometime a particular manufacturer will use different schemes, and many now use schemes that differ from what they used to use.

Surface mount ceramic capacitors usually have no marking at all!

 

I've seen a lot of different capacitors in my decades in electronics and have never seen one marked that way. A marking like 2n7 or 2u7, meaning 2.7 nF and 2.7 µF is common. I would take 2k7 to mean 2.7k picofarads = 2.7 thousand picofarads.. 2n7J400 is the marking I would expect.

J is standard for ±5% tolerance and 400 would normally be the DC voltage rating.

Sometimes you see voltage marked
~400
which would mean 400 VAC RMS

Really thanks for your reply , you helped me a lot ! Appreciate it thank you .
Sometimes you see a solid bar above a dashed line like
___
-----
in front of a voltage rating, which normally means the rating is DC volts

Sometimes you will see both a DC voltage rating and an AC voltage rating marked, but this isn't very common.

It has become very common to see capacitors marked in picofards as digit-digit-multiplier, so 103 would mean 10 x 10^3 picofarads. The marking method has the advantage that it covers 10 decades, from 100 (10 picofarads) to 999 (99 000 microfarads) with 3 characters, though it is rare to find it used above about 100 µF. This method isn't as common for capacitors that are physically large and there is room for other marking styles. But as WBahn says, different manufacturers do things differently. Sometime a particular manufacturer will use different schemes, and many now use schemes that differ from what they used to use.

Surface mount ceramic capacitors usually have no marking at all!