Gentlemen, The man has a pole TX 200 yards away. Where is he? Out in the sticks! So many of these comments are not entirely relevant are they? The pole TX may only be 11 kV to 230 and 50 kVA. Regulation 5%, ignoring any volt drop issues!

The problem with the oven is simply its control system, and here the defect is obvious too, the "temperature" input has zero hysteresis and the control is "0n-off". Whoever designed this is obviously incompetent! For an oven, heat loss is quite slow in response to temperature, so a half degree of hysteresis would be much better than any mechanical thermostat and perfectly adequate, one or two degrees similarly if necessary. A system with very high sensitivity to a variable (in this case temperature) and instant full scale response feedback is basically unstable and will show all these defects as described. The best system would be one with proportional feedback with the elements controlled by a PWM IGBT or thyristor power control (pretty cheap), which would be more accurate and not pulse the mains power level!

I would return the item as unfit for sale, they cannot fix it because the DESIGN is defective!

David CEng etc.

Hi David

Is it a pole TX?  I asked last night, but as yet no reply either way.

I was trying to establish visually whether 3-phase was available. 

Around here (n Wales) besides single phase pole TX connected across two of the three phase 11 kV overhead lines, there are also 2-wire 11 kV overheads, which obviously would have a much, much greater cost to upgrade.

There is also 230-0-230 split phase, to consider, but I doubt whether this would help in this case.

Clive

Hi David

Is it a pole TX?  I asked last night, but as yet no reply either way.

I was trying to establish visually whether 3-phase was available. 

Around here (n Wales) besides single phase pole TX connected across two of the three phase 11 kV overhead lines, there are also 2-wire 11 kV overheads, which obviously would have a much, much greater cost to upgrade.

There is also 230-0-230 split phase, to consider, but I doubt whether this would help in this case.

Clive

Hi Clive Sorry -I have been off this for a few days due to hunting down a gremlin on the hot water controls I have motor valves scattered hither and yon    with a N to E fault.  always a ***.-------I am up on the Horseshoe Pass Llangollen. It is a 3 wire 11kv line and a 50kva TX 440v -240v  serving three properties. The board only ran a single phase 50kva MD line to the place way back.