I have an observation about electrical power in Europe. Some fourteen years ago I lived in France. I needed a new alarm clock and bought cheap digital one from Lidl (German discounter active in France). The clock would lose time - sometimes hours a day I seem to remember. Generally in the Summer it kept better time.
On return, permanently, to the UK (yuk!!) my clock kept, and still keeps perfect time. I was puzzled until I learned that in the UK the power FREQUENCY is guaranteed to 50Hz within a fraction of a percent over a 24 hour period. In France, however, when there is a very large power demand, say regionally, they drop both the voltage and the supply frequency to avoid cutting power. My clock was a cheap one without its own timing oscillator; it was just using the mains 50Hz (Hertz or cycles per second) as the time-base. So with less cycles per second it counted less seconds. With less cycles per second the electrical power is less too.
It may well be for others, in esoteric (i.e. non anglicised) parts of the World, that the power supply has non-guaranteed frequency that will effect this little roaster.