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SK Capacitor

kidgreen

Jun 23, 2016
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Jun 23, 2016
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Good Morning,

I'm looking for a capacitor made by SK, it is out of a central heating pump.

It has the number MK 265N40BL stamped on it, also 2.6 pF, 400v AC.

I cannot find an alternative the same size, I have tried Farnell & RS Components.

If anybody can suggest a supplier, I would be very grateful.

Thanks in advance.
 

Harald Kapp

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Nov 17, 2011
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Welcome to EP.

Size is not important as long as the replacement fits in the available space.
Relevant parameters are:
  • Capacity 2.6 pF
  • Rated Voltage 400 V
Also possibly any approvals (UL, VDE...)

I wonder whether the data you give are correct. 2.6pF sounds like a very small capacitor - a few centimeters of wire in parallel suffice to achieve this. Can you post a photo of the capacitor with clearly visible markings?
 

kidgreen

Jun 23, 2016
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Jun 23, 2016
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Hi Harold,
Thank you for taking the time to reply.

I am a Gas Engineer, and have very little knowledge of electronics, this is a cap that has failed prematurely in a pump.

I have had to buy a new pump £218 !! just for the sake of this cap which I imagine will cost a couple of Quid.

I have uploaded a photo of said cap for your viewing pleasure

A replacement could be a few mm wider, but not much.

I don't know why it is rated at 400v, when the pump operates at mains voltage?

Thanks for your help.
 

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BobK

Jan 5, 2010
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That is 2.6uF, 1,000,000 times larger than the 2.6pF you stated! And it makes much more sense.

Look for motor start capacitors having the same 2.6uF and 400V rating. The voltage can be higher but not lower. It needs a 400V capacitor because 220V mains have a peak of over 300V. Motor start capacitors are stocked by electrical equipment supplier rather than electronics suppliers (at least here in the U.S.), so you might be looking in the wrong place.

Bob
 

Harald Kapp

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The exact value of the cap is not that important. 2.5µF...2.7µF will do.
400V is required: 230 V mains (RMS) = 325 V peak (*sqrt(2), add 20 % overvoltage -> 390 V et voilá.
Higher voltage rating is acceptable, lower is not acceptable.
 

kidgreen

Jun 23, 2016
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Brilliant, many thanks for your help.

A bright new start for Britain.:)
 
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