Microwave Ovens -- Construction and Operation
Microwave ovens use a wide variety of electrical circuits and mechanical components to produce microwave energy for heating and cooking [3]. There are two primary sections within a microwave: the control section and the high-voltage section. The control section consists of a timer (electronic or electromechanical), a system to control the major power output, and diverse interlock and protection devices. The components in the high-voltage section serve to increase the voltage. Higher and higher voltages are then converted to microwave energy.
When plugged into an electrical circuit, electricity enters the microwave oven through a series of fuse and safety protection circuits. These circuits include various thermal protectors that can also deactivate the oven in the event of overheating or a short [2]. Under normal circumstances, electricity passes through to the interlock and timer circuits. When an oven door is closed, an electrical path is created through a network of safety interlock switches. Once the operator sets the oven...
The control circuit generates a signal that causes the relay or triac to activate, thereby producing a voltage path to the high-voltage transformer. This high-voltage transformer, along with a special diode and capacitor arrangement, has the capacity to increase the typical household voltage of about 115 volts to as much as 3000 volts [1]. Such high voltage is required for the magnetron tube to convert the high voltage into undulating waves of electromagnetic cooking energy [3].
The microwave energy is transmitted into a metal channel called a waveguide, which feeds the energy into the cooking cavity of the microwave where it encounters the slowly revolving metal blades of the stirrer blade. Some models use a rotating antenna while others rotate the food through the waves of energy on a revolving carousel. Either way the goal is to evenly disperse the microwave energy throughout all areas of…
