Kiln blowing transformer with new elements

[Ossoceramic]

Hi all!

So I have a skutt 1027 single phase 240v 48amp kiln. I replaced the elements recently and then started having issues with my electrical. 

So I'm in a building with 208 power and I have a 240 kiln. There was a transformer (buck transformer?) already there in the space that my kiln got hooked up to. 60 amp breaker for the transformer. I had no issues when firing on my old elements but they were in desperate need of changing and finally tapped out. I changed the elements and then on my first cone 6 glaze fire, it totally melted down the transformer (literally). 

Replaced the transformer with a better one! And the first glaze firing I did went really well, it even fired to temp in 9.5 hours, which it never had before. It always used to take 12 hours at least, but I had no issues with that.  But on the third glaze firing with the new transformer, it blew again!

Could I have done something wrong in the wiring that is causing it to draw too much power? I followed the diagram and the kiln diagnostics seem to think it's fine. I will post photos of what it says. 

Would love any input you might have! I can't keep throwing money at this. The elements are new skutt elements that say they're rated for 240 or 208. I am assuming my building has single phase power and not three phase power otherwise it simply wouldn't work, right? 

[Mark C.]

My guess is your 208 is 3 phase -you will have to know this factor.You can convert to 240 singe phase with a phase converter . All og this converting is costly. Sounds like you need to learn a bit more about what your building has 1st. The buck transformers look pretty spendy .

[Ossoceramic]

I called Skutt to see what they would say and they told me that if it were 3 phase power, my kiln never would have worked without a converter. 

So I just need to replace my elements with 208 volt to bypass the need for the buck transformer altogether. 

This is a studio building but they didn't seem to know what kind of power it had. Wish they had told me before I blew two transformers and we could have avoided this issue from the beginning! Eye roll from me but I'll update once they rewire into the breaker box and I replace my elements to 208.

[PeterH]

What was the rating of the transformer(s)?

[Mark C.]

Yes the 208 elements would be the easy fix

[PeterH]

5 hours ago, Ossoceramic said:

I changed the elements and then on my first cone 6 glaze fire

2 hours ago, Ossoceramic said:

So I just need to replace my elements with 208 volt to bypass the need for the buck transformer altogether. 

I'm having trouble scoping things.

Without the buck transformer:
The 208V KM-1027 kiln only fires to cone 6 (the 240V fires to cone 10).
https://skutt.com/products-page/ceramic-kilns/km-1027/#specs
... if you regularly fire to cone 6 would the element life be a problem?

With the buck transformer:
1) The 240V KM-1027 draws 48A. If you are using a 208/240V buck transformer presumably the 208V side needed to draw 48*240/208=55.4A, does a 60A breaker meet the regs?
2) Was the transformer rated at >11,520W?

Edited June 20 by PeterH

[Bill Kielb]

208 V system voltage would indicate 3 phase. 208v leg to led and usually 120v leg to neutral. A Buck transformer usually is referred to as buck when the voltage is reduced and boost when voltage is increased. In essence an auto transformer hooked up to boost or buck the present voltage. As @PeterH mentioned, just changing the elements in this kiln to 208v (single phase) results in prox. 9000 w machine. Much less capability. I think easier to change to 3 phase 208 v wiring and 3 phase 208 v elements resulting in a prox 11000w machine.

So better clarification on what is available currently and likely rewire the kiln for three phase 208 v wiring with three phase 208v elements. An autotransformer that boosts the current 208 v leg to leg to 240v single phase would be pricey.

closest I find is 600.00 range and  likely too small for 11500 w. Change you kiln  to three phase wiring and 3 phase 208 elements much easier and in line with skutts design.

 

 

Edited June 21 by Bill Kielb

[neilestrick]

If you have 3" bricks it's rated to cone 10. With 2.5" bricks it's more like cone 8. Their cone 6 rating is very conservative imo.