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brightspark
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use the 4mm
Please excuse possible hijack, but how important is stable voltage on a generator to using a welder with it?
A boot sale I went to had a 1Kw job going for £45, but the seller told me he'd found it no use for electronic gear due to fluctuations in the voltage. I phoned a pal and he reckoned it didn't have a smoothing capacitor.
Any thoughts?
A boot sale I went to had a 1Kw job going for £45, but the seller told me he'd found it no use for electronic gear due to fluctuations in the voltage. I phoned a pal and he reckoned it didn't have a smoothing capacitor.
Any thoughts?
rich r
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Simple maths:
Average small arc welder (let's say a cheap AC buzzbox) capable of using 3.2mm E6013 rods would produce a welding output of 110A at around 25V.
P=VI, so output power is 25 x 110 = 2.750kW
If we assume the transformer is 90% efficient then that's 2750/0.9=3.055kW.
Which is almost triple what a 1kW generator can supply. With a mains supply at 230V, that means 3055/230=13A, minimum.
Hence why you can just about use 3.2mm rods on a normal 13A plug, with the fuse blowing occasionally.
Also generators don't like sudden changes in load, so although it looks like a 3kW generator might just do the job, it'll probably cut out or the voltage would drop when you start welding, leading to poor performance. You need to be looking much bigger - and ideally a welder that actually states that it's suitable for powering welding equipment in it's specifications.
Average small arc welder (let's say a cheap AC buzzbox) capable of using 3.2mm E6013 rods would produce a welding output of 110A at around 25V.
P=VI, so output power is 25 x 110 = 2.750kW
If we assume the transformer is 90% efficient then that's 2750/0.9=3.055kW.
Which is almost triple what a 1kW generator can supply. With a mains supply at 230V, that means 3055/230=13A, minimum.
Hence why you can just about use 3.2mm rods on a normal 13A plug, with the fuse blowing occasionally.
Also generators don't like sudden changes in load, so although it looks like a 3kW generator might just do the job, it'll probably cut out or the voltage would drop when you start welding, leading to poor performance. You need to be looking much bigger - and ideally a welder that actually states that it's suitable for powering welding equipment in it's specifications.
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It's best to work on a generator supplying 3X the rated input power of your welder.
Lawnmowerboy
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also a friend ruined his r-tech inverter stick by running it off a genny
the snooper
getting older by the day
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they dont have them, they either have capacitor voltage regulation
or an AVR Automatic Voltage Regulator the later of the two does have very stable voltage
smoothing capacitors are found in power supplies that require a regulated stable DC output
problem with small gennys is the time it takes for the govoner to react and rotating mass.
i have a very old genny thats rated at only 4kw and a much more modern one rated at 6 kw, the old fecking heavy genny has so much inertia in its flywheel that it hardly notices you strike an ark with a 4mm rod but the newwer 6kw coughs and bangs a bit.
if the genny struggels to react to the load the volts fall with or without AVR and so dose the frequency some inverters dont like that
i have a very old genny thats rated at only 4kw and a much more modern one rated at 6 kw, the old fecking heavy genny has so much inertia in its flywheel that it hardly notices you strike an ark with a 4mm rod but the newwer 6kw coughs and bangs a bit.
if the genny struggels to react to the load the volts fall with or without AVR and so dose the frequency some inverters dont like that
BillFarworth
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rich r ,
If we have 110A at around 25V
If we have 130A or 150A does the V stays @ 25V?
Forgive me for my pure maths!
Thanks
If we have 110A at around 25V
If we have 130A or 150A does the V stays @ 25V?
Forgive me for my pure maths!
Thanks
rich r
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It does vary slightly depending on the output current (depends on the welder - inverters are better than buzzboxes), but it's only a volt or two. I think my buzzbox is 21V at 55A and 25V at 160A.
Arc welding is really a constant current process, so the voltage will vary a little depending on the arc length as it tries to keep the current the same (longer arc requires more voltage to keep the arc going). But for rough power calculations it's probably reasonable to assume it's constant at about 25V for most arc welders.
Arc welding is really a constant current process, so the voltage will vary a little depending on the arc length as it tries to keep the current the same (longer arc requires more voltage to keep the arc going). But for rough power calculations it's probably reasonable to assume it's constant at about 25V for most arc welders.
BillFarworth
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Sorry rich r,
Not understand what the 25V is?
You mean 25 Volt on what?
I thought the Welder works on 230V
My welder states Max Open Circuit Volts @ 97?
Forgive my pure Knowledge here!
Not understand what the 25V is?
You mean 25 Volt on what?
I thought the Welder works on 230V
My welder states Max Open Circuit Volts @ 97?
Forgive my pure Knowledge here!
shenion
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The welding voltage is about 18 to 28V (about 30 to 200A IIRC).
The arc length will vary the voltage. Drag the rod and it may be 19, use a 2mm gap and it might be 27. The current will be near the same in both.
The OCV is the no-load voltage and the max it can do to maintain the current. When welding, the voltage will vary wildly. A higher OCV helps keeping the arc from blowing out.
The arc length will vary the voltage. Drag the rod and it may be 19, use a 2mm gap and it might be 27. The current will be near the same in both.
The OCV is the no-load voltage and the max it can do to maintain the current. When welding, the voltage will vary wildly. A higher OCV helps keeping the arc from blowing out.
rich r
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The 25V is the sort of voltage most arc welders produce at their output (ie between the electrode rod and the earth clamp) when an arc is present. Hence my original statement:
If you consider the welder to simply be a transformer that swaps voltage for current, then regulates that current, you can see that for example, an output of 80A at 25V requires an input of (80*25)/230=8.5A at 230V
As Shenion said- in practice the output voltage varies as the welder tries to keep the current at the output constant. But for the purposes of working out the current being drawn from the supply, it's sensible to assume it's around 25V.
The open circuit voltage is what's present at the output when there's no arc present. The higher this is, the easier it is to strike an arc - but the welder has to bring that voltage down once the arc is present, otherwise it'll draw a huge current from the supply in order to keep the output current at the required level.
If you consider the welder to simply be a transformer that swaps voltage for current, then regulates that current, you can see that for example, an output of 80A at 25V requires an input of (80*25)/230=8.5A at 230V
As Shenion said- in practice the output voltage varies as the welder tries to keep the current at the output constant. But for the purposes of working out the current being drawn from the supply, it's sensible to assume it's around 25V.
The open circuit voltage is what's present at the output when there's no arc present. The higher this is, the easier it is to strike an arc - but the welder has to bring that voltage down once the arc is present, otherwise it'll draw a huge current from the supply in order to keep the output current at the required level.
BillFarworth
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A Ok now i understand Guys!
I just want really to figure out if I am able to use a 1.5 (Maximum Watt of 3500 in 16A Fuse) extension cable for my welder?
If I go at 100A to 120A with my welder I assume there is no issue there
I just want really to figure out if I am able to use a 1.5 (Maximum Watt of 3500 in 16A Fuse) extension cable for my welder?
If I go at 100A to 120A with my welder I assume there is no issue there
There was recommendation on this site a while back from Brightspark to use 2.5mm squared arctic cable for an extension lead as it is the thickest wire that you can wire to a 13 amp plug.
I have done this and no longer blow any fuses using my 150amp clarke welder on full power. I previously used a 1.5mm squared extension lead and my set up occasionally blew fuses although admittedly this extension lead was about 6 meters longer.
1.5mm squared cable will probably do you for 120amps but if you haven't bought the lead yet I would recommend you buy some thicker cable if you can to give you some more headroom.
I have done this and no longer blow any fuses using my 150amp clarke welder on full power. I previously used a 1.5mm squared extension lead and my set up occasionally blew fuses although admittedly this extension lead was about 6 meters longer.
1.5mm squared cable will probably do you for 120amps but if you haven't bought the lead yet I would recommend you buy some thicker cable if you can to give you some more headroom.
