Arrangement for controlling the microwave power of magnetrons

In a microwave heating apparatus including a power unit, a plurality of magnetrons, each having an anode, connected in parallel with the power unit, said power unit having two output terminals, one of which is grounded, enabling generation of a requisite high magnetron-operating voltage, a plurality of waveguides each of which is connected to an associated magnetron, a controlling device comprising for each magnetron (1, 2;

• 60, 61):
• a separate regulating circuit (9) which includes a measuring means (10) for measuring the anode current through respective magnetrons;
• the wave-guides (70), to which the magnetrons are connected, are connected to said ground potential;
• an electrically isolating means connecting the anode (4;
• 62, 63) of each magnetron (1, 2;
• 60, 61) to the grounded waveguide so that each said anode is isolated electrically from the ground potential;
• each said measuring means 91) being connected between the anode (4;
• 62, 63) of its associated magnetron and the other said output terminal (23), of the power unit (3), which has a positive potential;
• and an overvoltage protector (78) is connected in parallel to each said measuring means (10) so as to limit the voltage on the associated anode (4;
• 62, 63) of its associated magnetron in the event of a disruption or break-down of the associated measuring means (10).