208/240 oven

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Richard M

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brookeville md. usa
Today I was called in because an oven would not work, there was a power outage and when the power came back on the oven would not work. Checked everthing out all was good.Then I noticed that the oven is 208/240 3phase 40a 9600w and is connected to a 120/240 single phase 40a 2p and has been working fine only 3 months old. could the power source be the problem ?
 
Not sure what the problem was but I am assuming this oven must be capable of being hooked up to either sp or 3 phase.
 
The oven was not working fine. It was working poorly at best. One of its heating elements was not being used. So it would have taken longer to heat up. Perhaps the owner had not noticed, perhaps because they had nothing to compare its performance against. But it was not fine.

Also, I don't think you checked everything. Something is not right. Obviously, it is either the power supply or the internals of the oven. I can't help with solving the mystery without knowing more about what tests you tried and what results you got.
 
Richard M said:
Today I was called in because an oven would not work, there was a power outage and when the power came back on the oven would not work. Checked everthing out all was good.Then I noticed that the oven is 208/240 3phase 40a 9600w and is connected to a 120/240 single phase 40a 2p and has been working fine only 3 months old. could the power source be the problem ?
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Can you give us more details on both the oven specifications and how it is installled?

This doesn't add up:"the oven is 208/240 3phase 40a 9600w",
240 single phase 9600 watts would give you 40 amps. If watts remains constant three phase amps would have to be less, and should be about 23 amps if all three phases are balanced.

If it is 9600W and can be connected across three phases - there may likely be three 3200 watt elements. Connect them in a delta configuration and apply full rated voltage to all three corners of the delta and you get full 9600 watts balanced across three phases. No three phase available? you can still connect all three elements parallel to each other and apply 240 volts and you still get 9600 watts @ 40 amps single phase. Connect them in the delta configuration and mistakenly apply 240 single phase plus neutral to the other corner of the delta and you will have full 3200 watts from the one element connected to 240 volts, the other two elements will only be seeing 120 volts across them and watts output will only be 1/4 of rated so 800 and 800, that added to the 3200 watt element gives us 4800. So the unit was probably operating at only half the rated watts from the beginning. It may reach setpoint temps but will take longer to attain them, and will have slower recover times after opening the door(s).

Much of this is assuming the unit is rated for both single/three phase connection with same output rating, and that it has a lower rating for 208 volts.
 
208/240

208/240

Richard M said:
Today I was called in because an oven would not work, there was a power outage and when the power came back on the oven would not work. Checked everthing out all was good.Then I noticed that the oven is 208/240 3phase 40a 9600w and is connected to a 120/240 single phase 40a 2p and has been working fine only 3 months old. could the power source be the problem ?
Click to expand...

thinks guys i will go back and check.I know the oven is a new Turbo Chef and the cord was set up for 2p 40a The owner didn`t want me to open it because of warrenty and down the street a transformer did blow up.
 
Richard M said:
thinks guys i will go back and check.I know the oven is a new Turbo Chef and the cord was set up for 2p 40a The owner didn`t want me to open it because of warrenty and down the street a transformer did blow up.
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AFAIK the only way that it could be the power source would be if one side of the 120/240 got permanently interrupted somehow.
Otherwise more likely that a surge associated with the power outage blew up an electronic control module.
 
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