Industrial Oven

[Black Garlic]

I've got an industrial oven 100amps over three phases. I had an electrician wire it up (charged me £900! it took 5 hours and there were two of them!) and it works. The electrician then said as they were packing up, that it was surging. It pulled 97 amps when switched on, then when it gets up to temperature, it idles at 40 amps but every three seconds it surges to 97.3 amps. The electrician left and went straight to the owners of the unit and said this was a fire risk. He didn't say it was a fire risk to me just that it might F$%k up my panel board.

What I really need to know is how might I stop the oven from surging? I think 100 amps over 3 phases sounds a bit much when the actual oven shouldn't get above 100 degrees centigrade.

Any help or advice would be greatly appreciated

 

[snowhead]

The "Surging" is caused by the Thyristor controllers at the bottom of the panel, it's a characteristic of a modern commercial oven, not a fault.

Can you psot details of the oven, make model, to show exact current rating etc.

 

[Black Garlic]

Thanks for that! I'll look at it tomorrow and see if I can find that out.

 

[Knobhead]

The surging as has been said is normal. It’s done to maintain a stable temperature in the oven.
You will have a “base” load to hold a minimum temperature.
A “boost” to raise the temperature from cold.
I wouldn’t be at all surprised if there isn’t an “intermediate” power to hold steady once up to normal operating temperature.

The only fire risk is any inadequacies in the installation, which is down to your electrician. Get him back to explain his self!

 

[Deleted member 26818]

I wouldn't have thought that a lag of only 3 seconds was right.
Must be a very sensitive thyristor, or the setting on the controler is very precise.
I'd be expecting a lag somewhere between 30s and as much as 3 mins.
Can't say that I've had much to do with modern ovens though.
On an older oven, I'd be looking for a leak, or missing insulation.
I'm also suprised that the minimal load is as much as 40A, I imagine that the oven is a rotary, perhaps a bread oven, or a conveyor pizza oven?

 

[Engineer54]

The surging as has been said is normal. It’s done to maintain a stable temperature in the oven.
You will have a “base” load to hold a minimum temperature.
A “boost” to raise the temperature from cold.
I wouldn’t be at all surprised if there isn’t an “intermediate” power to hold steady once up to normal operating temperature.

The only fire risk is any inadequacies in the installation, which is down to your electrician. Get him back to explain his self!

Agree, but i wouldn't bother with the installation electrician, far better to contact the manufacturers of this oven and get them to explain the operation to you!! After all they designed the controls of this industrial oven....

By the way a 100C working temperature can take a fair bit of time to reach and stabilise depending on the volume/size of the oven....

 

[Knobhead]

I’ve never had involvement with “commercial” ovens, my involvement has been with analytical kilns. The principle is the same but on a different scale. This is why I thought along the lines of a three stage control.

As E54 says contact the manufacturers.

 

[Black Garlic]

Thanks everyone lots of welcome lines of enquiry.