ID capacitor ? (from a power tool, not audio)

[00940]

This is not audio but knowing all the experts about all things electronic lurking around...

Any idea what this cap is (beside the fact that it is a 0.25uf/250vac cap) and where to find a replacement ? It's coming from a power grinder.

Marking:

V250 R/4
0,25µf
250v~ -20°
+80°c 66.11
1 607 329 001

 

[simon7000]

Take it apart a bit more to see how the wires are connected to the foil. How many pieces of foil? It could be a simple capacitor across the wires in an inline package, if there are no other bits. Then there are a wide variety of capacitors designed and rated for such use. Voltage, temperature and capacitance all seem normal but it must be specially rated for AC line use.

What is the make and model of the tool? Are the motor brushes good? Do they arc a lot indicating a shorted armature winding?

 

[Elvee]

It is an oldish in-line suppression cap, probably paper-based.

Just strap the in/out terminals, and connect a 0.33µ 250V AC X type across instead.

 

[JMFahey]

Please remember 250VAC rated cap is not a standard "250V cap" by any means.

The latter rating applies to DC only; this is a heavy duty "Industrial" type cap.

 

[PRR]

> this is a heavy duty "Industrial" type cap.

Apparently not "heavy duty" enough.

Considering a 250V rating is barely covering modern "240V" wall outlets, you might shop for a higher rating.

 

[JMFahey]

> this is a heavy duty "Industrial" type cap.

Apparently not "heavy duty" enough.

I am warning him about not using an "amplifier type" "250V" labelled capacitor; and to get the proper one.

Considering a 250V rating is barely covering modern "240V" wall outlets, you might shop for a higher rating.

These are not "Zener Capacitors" which stand 249VAC forever and explode at 251VAC

240V and even 250V nominal power lines, including standard mains variations are well within ratings; 250VAC labelled caps go through very rough and damaging testing.

A couple free samples, all applying to 250VAC caps:

Impulse Test Waveform

An externally hosted image should be here but it was not working when we last tested it.

T1= 1.2 second, T2=500 second in Mains power applications (IEC 60384-14)

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This is a 1000 hour AC life test where parts are subjected to 425 VAC/60 Hz, with a 1000 Vrms pulse, once per hour, lasting 0.1 seconds.

I am not talking about the old capacitor but the new one which must be fit there as replacement.

 

[00940]

Thank you all for the info. I've got a few X rated caps pulled from old computer PS, I assume I could use these, adding suitably isolated leads ?

I don't know much about the actual tool; a friend just dropped the cap on me, asking for a replacement.

 

[Glenn E]

You can always post on electronics.stackexchange
Glenn

 

[Elvee]

Thank you all for the info. I've got a few X rated caps pulled from old computer PS, I assume I could use these, adding suitably isolated leads ?

Maybe, but be aware that X caps wear out with time: each time they see a voltage "event", they lose a bit of their metallization, and after some years of service, they might have lost 90% of their capacitance, sometimes more depending on the "harshness" of the local mains

 

[00940]

OK, in this case, I'll order a proper new X1 cap.

Thanks for the help.

 

[audio king]

I would think it's a two-section arc suppressor mounted across the power switch to protect the contacts.In Europe,doesn't 240V service require breaking both lines on equipment?

 

[Michael Bean]

I prefer to use a R/C suppressor like this:
https://www.digikey.com/products/en?keywords=399-12027-ND
They are usually better for reducing EMI/RFI than just a single capacitor.

Mike