Duty Cycle Ignored: Pop - hisssss

[Richard.]

It should state the duty cycle on the machine at various settings for example full power weld 10 mins rest it for 10 mins, this is just an example so take no notice of those times

Yes it works on a ten min basis usually but it will state it as a % over a current at a temp.
My machine is 35% at 220amps in 40 degreeC conditions.
So at 220 amps after 3 and a half mins I need to go have a cuppa for at least 6 and a half mins to keep it happy.

 

[Questions]

In your post I replied to you wrote, so check you have ac coming from the diodes

Ah, thanks a bunch for that, have changed it now, very misleading.

 

[Questions]

I would agree the duty cycle on transformer based machines mainly applies to the core temperature of the transformer, capacitors are in use on various things 24 hours a day all year round

I posted that caps could blow because of over heating, and of course I could be wrong, it just seemed to me that if
the caps were designed to function at a certain voltage over a certain period, that period being the duty cycle
of the welder then over heating them could occur, as not enough time was allowed to cool them or keep them cool
hens heat building up to a point where it began to break down the functionality of the cap, which when started would
continue to escalate until failure would occur.
But as I said, I am no expert at all in this.

 

[the snooper]

I posted that caps could blow because of over heating, and of course I could be wrong, it just seemed to me that if
the caps were designed to function at a certain voltage over a certain period, that period being the duty cycle
of the welder then over heating them could occur, as not enough time was allowed to cool them or keep them cool
hens heat building up to a point where it began to break down the functionality of the cap, which when started would
continue to escalate until failure would occur.
But as I said, I am no expert at all in this.

capacitors can run forever as long as the voltage to them is within spec, motors are fitted with them, they are in tvs, radios, if its electronic it will have them in, in varying forms, sizes, values, and voltages.

When I say forever I don't mean they will last forever, they will eventually break down

 

[Questions]

capacitors can run forever as long as the voltage to them is within spec, motors are fitted with them, they are in tvs, radios, if its electronic it will have them in

Well that the kind of answers a man called Questions like to get, thank's.

 

[WorkshopChris]

all I can find out about these caps is that they are 80v, 105°C, 4700μF. What should I be looking for?

If possible you want to find capacitors classed as low esr ideally high tolerance form a trusted manufacture.

 

[HughF]

http://www.ebay.co.uk/itm/Large-Ele...hash=item3aa68d5257:m:mETeGlUg9co5mrq6Qn5D7Ng

100v 4700u, 4.80 each

 

[Jim Davey]

I find caps often fail when sets are used hard off long/undersized supply cables. Beef up your extension leads or work directly of a good mains socket wherever possible and avoid the use of 1.5mm2, 15 metre wind-up extension leads, they are murder.