Home Page link

Three phase for a resistance load??

Home| Search | About
Login Password
Register Now! Lost Password?

Home Repair - - If it ain't broken, don't fix it. Otherwise look here. 

Page 1 of 2       1 2 > last >> Bookmark this page:  YahooMyWeb Yahoo!  Google Google  Windows Live Favorites Windows Live  del.icio.us del.icio.us  digg digg  Add to Netscape Netscape
Subject Author Date
Three phase for a resistance load?? Vic Dura 09-20-2006
If you were  Registered and logged in, you could reply and use other advanced thread options
Posted by Vic Dura on September 20, 2006, 8:14 am
Hello,

The engineers in sci.engr.electrical.sys-protection were useless on
this question, so I thought I would ask it here where the *real*
knowledge is.

The question is regarding the use of 3-phase power. I noticed an
electric pottery kiln the other day that used 3-phase power. It was
about a 6 or 7 kw model. As I understand it, electric kilns are
resistance loads, just like a toaster oven.

I had always thought that 3-phase power was an advantage only for
induction loads, and had no advantage over single-phase for resistance
loads. Is that correct? If so, what would the advantage be for a
3-phase kiln such as those shown at

http://www.skutt.com/products/elec_req.htm ?

Thanks for any enlightenment.
--
To email me directly, remove CLUTTER.

Posted by Pete C. on September 20, 2006, 8:43 am
Vic Dura wrote:
>
> Hello,
>
> The engineers in sci.engr.electrical.sys-protection were useless on
> this question, so I thought I would ask it here where the *real*
> knowledge is.
>
> The question is regarding the use of 3-phase power. I noticed an
> electric pottery kiln the other day that used 3-phase power. It was
> about a 6 or 7 kw model. As I understand it, electric kilns are
> resistance loads, just like a toaster oven.
>
> I had always thought that 3-phase power was an advantage only for
> induction loads, and had no advantage over single-phase for resistance
> loads. Is that correct? If so, what would the advantage be for a
> 3-phase kiln such as those shown at
>
> http://www.skutt.com/products/elec_req.htm ?
>
> Thanks for any enlightenment.
> --
> To email me directly, remove CLUTTER.

The advantage is lighter gauge supply wire and smaller control
contactors since you are dividing the load across three wires instead of
two with the resulting lower current per wire. You also balance the load
across all three power phases in the building as opposed to
concentrating the load on only two phases. No other particular
advantages.

Pete C.

Posted by DK on September 20, 2006, 8:53 am
wrote:

>Vic Dura wrote:
>>
>> Hello,
>>
>> The engineers in sci.engr.electrical.sys-protection were useless on
>> this question, so I thought I would ask it here where the *real*
>> knowledge is.
>>
>> The question is regarding the use of 3-phase power. I noticed an
>> electric pottery kiln the other day that used 3-phase power. It was
>> about a 6 or 7 kw model. As I understand it, electric kilns are
>> resistance loads, just like a toaster oven.
>>
>> I had always thought that 3-phase power was an advantage only for
>> induction loads, and had no advantage over single-phase for resistance
>> loads. Is that correct? If so, what would the advantage be for a
>> 3-phase kiln such as those shown at
>>
>> http://www.skutt.com/products/elec_req.htm ?
>>
>> Thanks for any enlightenment.
>> --
>> To email me directly, remove CLUTTER.
>
>The advantage is lighter gauge supply wire and smaller control
>contactors since you are dividing the load across three wires instead of
>two with the resulting lower current per wire. You also balance the load
>across all three power phases in the building as opposed to
>concentrating the load on only two phases. No other particular
>advantages.
>
>Pete C.

Exactly.


Posted by Chris Lewis on September 20, 2006, 12:59 pm
> Vic Dura wrote:

> > I had always thought that 3-phase power was an advantage only for
> > induction loads, and had no advantage over single-phase for resistance
> > loads. Is that correct? If so, what would the advantage be for a
> > 3-phase kiln ...

> The advantage is lighter gauge supply wire and smaller control
> contactors since you are dividing the load across three wires instead of
> two with the resulting lower current per wire. You also balance the load
> across all three power phases in the building as opposed to
> concentrating the load on only two phases. No other particular
> advantages.

The advantages Pet mentions are relatively minor in a smallish kiln like
this.

The other advantage is much simpler to understand: "because it interfaces
with 3 phase power".

Kilns like this are most often situated in light industrial or commercial
buildings. Such buildings are usually fed with three phase. Aside
from general purpose outlet circuits (and _some_ lighting), the higher
power circuits (ones you'd sling 30A at 240V devices on) are virtually
all 3 phase (or 2 phase of 3) devices.

Which is why, for example, in large commercial wood working shops, even
the smaller tools (eg: a 14" bandsaw with a 1HP motor, which'd
normally be on a 15A 120V circuit in a home hobbyist's house) are
three phase.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Posted by Bill Gill on September 20, 2006, 9:01 am
Vic Dura wrote:
> Hello,
>
> The engineers in sci.engr.electrical.sys-protection were useless on
> this question, so I thought I would ask it here where the *real*
> knowledge is.
>
> The question is regarding the use of 3-phase power. I noticed an
> electric pottery kiln the other day that used 3-phase power. It was
> about a 6 or 7 kw model. As I understand it, electric kilns are
> resistance loads, just like a toaster oven.
>
> I had always thought that 3-phase power was an advantage only for
> induction loads, and had no advantage over single-phase for resistance
> loads. Is that correct? If so, what would the advantage be for a
> 3-phase kiln such as those shown at
>
> http://www.skutt.com/products/elec_req.htm ?
>
> Thanks for any enlightenment.
Looking at the web page you linked to it is obvious to
me that the 3-phase kilns are special purpose. They
clearly state that they are special order only. I
assume they are for use where you only have 3-phase
available.

Bill Gill

Page 1 of 2       1 2 > last >>
Similar ThreadsPosted
3-phase used for 1-phase (split-phase) power July 20, 2006, 12:16 am
Single Phase Backup Generator to Three Phase Mains Supply? January 22, 2008, 2:28 am
Single phase vs. three phase air conditioning February 3, 2006, 12:59 am
How to measure resistance? October 30, 2006, 7:03 pm
Re: White Resistance October 28, 2007, 9:34 pm
Urethanes and water resistance July 4, 2005, 4:34 pm
Three phase AC July 29, 2005, 3:33 pm
I have FOUR phase electricity January 2, 2008, 7:46 am
Where can I get plugs to fit this three phase socket? October 22, 2005, 3:21 am
240 V breaker/phase question October 31, 2005, 11:55 am

Contact Us | Privacy Policy

XML SitemapXML Sitemap