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 ?
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.
