When buying an oven, you should choose a model on power electricity 3 phase.
Volt: 400-230 / 3N 50-60Hz 3 phase 6200W
Volt : 230/1N 50-60Hz 230/1 3600W
Because of this choice you have an oven that is always on temperature, even if you fill it completely with products.
If possible buy a model with, Volt: 400-230 / 3N 50-60Hz.