# A countertop oven (Jetstream) 110V 60Hz versus 110V 50Hz - problems?

I have a Jetstream countertop oven that expects 110V at 60Hz. I have been using it lately in 230V country courtesy of a pretty massive stepdown transformer that is rated at 1500W but of course outputs 110V at 50Hz.
The oven seems to work okay (the electronics are fine of course since they are DC) and I suspect the motor is okay also since I would expect that to be DC also. But the perspex oven cover gets uncomfortably hot and has started to crack from the heat. I am wondering if this is because the actual heating element is rated for 110V at 60Hz operation and doesn't like 110V at 50Hz? From a distant past I recall that power for DC was Volts*Amps or I**2*R. But for AC you had to take the RMS value of the voltage rather than the nominal voltage? So potentially the heater is operating at a higher power (heat output) than it was designed for?
As an aside I recall my US house had to have 240V at 60Hz for a drier since not enough power could be supplied at 110V whereas in my local house abroad, since the entire house is wired for 230V 50Hz there is no need for a separate line for high current draw appliances.
Anybody who is more familiar with some of the basic electrical theory able to cast some light on this?
Thanks
Larry
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Most likely the motor is AC and will run slower on 50 hz. The heating elements don't care what the frequency is. They will put out the same ammount of heat with any frequency that is in common use.
Without really getting into it, the stated voltages are RMS. That is also the DC equivilent heating voltage. That is for a heating element 110 volts DC or AC (any frequency) RMS will heat the same
I don't know anything about your particular stove, but it may be the slow running motor is causing the problem by not moving enough air.
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I guess that makes sense. Shows up how far in the distant past my physic was :-(

I hadn't thought of that. The motor runs fairly fast - I am guessing at over 500 up to 1000 rpm. I presume with the right windings on the motor, it can be configured to rotate that fast based on the mains frequency? But what puzzles me is, the motor has two speeds (low and high) controlled by an electronic switch. Perhaps that switches from one to another set of coils on the motor to give the two speeds?
The actual unit is a later model of this
http://nesco.com/products/?category `0
the difference apparently being the motor now drives the fan directly rather than via a belt that is susceptible to breaking
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