|
Posted by Ignoramus11754 on May 30, 2006, 9:04 am
Please log in for more thread options
I have a SCR fired welding machine on a phase converter. I suspect
that it has a bad power factor.
For example, I could be creating 200 amps an 2 or so volts (creating a
short by connecting work clamp to electrode clamp).
Power wise, I am creating perhaps 400 watts of power. Add to that
another 600 watts of heat generated by SCRs. Add to that some current
needed to spin 17.5 HP worth of idler motors. The total amount is
rather small. Surely under 3 kW, which at power factor of 1, would be
about 13 amps at 240V single phase (likely a lot less than that).
And yet, the current measured on my single phase supply (going to
phase converter) is huge, about 60 amps. I explain this by saying that
this welder has a low power factor when used in the described manner.
My question is, can I do something such as adding (maybe dynamically)
some power factor correction capacitors, or some such, to correct that
power factor? Is such a thing doable relatively inexpensively?
i
|
|
Posted by Pooh Bear on May 30, 2006, 9:45 am
Please log in for more thread options
Ignoramus11754 wrote:
> My question is, can I do something such as adding (maybe dynamically)
> some power factor correction capacitors, or some such, to correct that
> power factor? Is such a thing doable relatively inexpensively?
It's a bit complicated.
It may not be mandatory for you to use PFC anyway.
Graham
|
|
Posted by Ignoramus11754 on May 30, 2006, 9:49 am
Please log in for more thread options On Tue, 30 May 2006 14:45:29 +0100, Pooh Bear
>
>
> Ignoramus11754 wrote:
>
>> My question is, can I do something such as adding (maybe dynamically)
>> some power factor correction capacitors, or some such, to correct that
>> power factor? Is such a thing doable relatively inexpensively?
>
> It's a bit complicated.
>
> It may not be mandatory for you to use PFC anyway.
Are you saying that I am not required by my power company to do that?
I would agree, yes. The main reason for my question is that with some
PFC, I could use my [marginal] 60A garage circuit more effectively.
i
|
|
Posted by Pooh Bear on May 30, 2006, 10:13 am
Please log in for more thread options
Ignoramus11754 wrote:
> On Tue, 30 May 2006 14:45:29 +0100, Pooh Bear
> >
> >
> > Ignoramus11754 wrote:
> >
> >> My question is, can I do something such as adding (maybe dynamically)
> >> some power factor correction capacitors, or some such, to correct that
> >> power factor? Is such a thing doable relatively inexpensively?
> >
> > It's a bit complicated.
> >
> > It may not be mandatory for you to use PFC anyway.
>
> Are you saying that I am not required by my power company to do that?
Not knowing the precise details I couldn't actually say but I wouldn't fret
excessively over it
right now.
> I would agree, yes. The main reason for my question is that with some
> PFC, I could use my [marginal] 60A garage circuit more effectively.
Is the mains ac connected to a classic transformer, rectifier, capacitor DC
supply ?
Graham
|
|
Posted by Ignoramus11754 on May 30, 2006, 10:22 am
Please log in for more thread options On Tue, 30 May 2006 15:13:32 +0100, Pooh Bear
>
>
> Ignoramus11754 wrote:
>
>> On Tue, 30 May 2006 14:45:29 +0100, Pooh Bear
>> >
>> >
>> > Ignoramus11754 wrote:
>> >
>> >> My question is, can I do something such as adding (maybe dynamically)
>> >> some power factor correction capacitors, or some such, to correct that
>> >> power factor? Is such a thing doable relatively inexpensively?
>> >
>> > It's a bit complicated.
>> >
>> > It may not be mandatory for you to use PFC anyway.
>>
>> Are you saying that I am not required by my power company to do that?
>
> Not knowing the precise details I couldn't actually say but I
> wouldn't fret excessively over it right now.
Yes, I am not worrying about the power company.
>> I would agree, yes. The main reason for my question is that with some
>> PFC, I could use my [marginal] 60A garage circuit more effectively.
>
> Is the mains ac connected to a classic transformer, rectifier, capacitor DC
supply ?
The scheme is as follows:
Mains 240VAC 1 phase
====> Phase Converter
====> Welder
The "Welder" is actually as follows:
3 phase in
====> 3 phase transformer
====> 3 phase rectifier bridge with SCRs (controlled by a "firing system"
====> Welding reactor (inductor)
====> Welding arc (or short as I tried)
So, when I tried getting 200 amps into a short, I would get about 60A
current (14 kVa) coming from the single phase mains, even though the
power used and wasted in the system was no more than 2-3 kW.
I am sure that power factor improves as welding arc voltage increases
from almost zero, but it is probably still low. It is hard to read
mains amperage when I have a arc going. :)
I could get some real benefit in terms of blown breakers, and weld
capacity, I think, if I could increase my power factor.
Hence my question.
i
|
| Similar Threads | Posted | | Re: Arc welder to power Krypton Arc lamp ?? | April 1, 2007, 12:58 pm |
| Re: Arc welder to power Krypton Arc lamp ?? | April 1, 2007, 12:58 pm |
| WTB Panasonic Weld Power supply | June 19, 2007, 3:19 pm |
| WTB Panasonic Weld Power supply | June 19, 2007, 3:20 pm |
| Power requirements for Miller Dialarc? | July 7, 2007, 10:22 am |
| Price Advice on Miller DialArc 250 AC/DC CC Power Source | April 25, 2008, 9:28 am |
| rich welder - sell Welding Equipment & Machines & mask,Power Tools,Motorcycle & Welding helmet,CUT,TIG,MIG,MMA,BX welder | June 30, 2008, 2:20 am |
|
|
Yahoo! 
Google 
Windows Live 
del.icio.us 
digg 
Netscape 
XML Sitemap
> some power factor correction capacitors, or some such, to correct that
> power factor? Is such a thing doable relatively inexpensively?