Question

If the one end of the secondary winding is connected to the core of the transformer which is connected also to the microwave oven body, why don't we get shocked by touching the oven?

Answer 1

The reason why you don't get shocked when touching the microwave oven is due to the design of the microwave's electrical circuit and its grounding system.

In a properly designed and functioning microwave oven, the primary and secondary windings of the transformer are isolated from the external circuitry, including the metal body of the microwave. The transformer's core is usually connected to the metal chassis of the microwave oven, but the secondary winding, which connects to the high-voltage components, is electrically isolated from the core and the chassis.

Here's how it works:

1. Isolation:

   • The primary winding of the transformer is connected to the microwave's power supply, which is designed to provide the necessary electrical energy to the transformer.
   • The secondary winding of the transformer is connected to the high-voltage components that generate the microwave energy. These high-voltage components are isolated from the external circuitry, including the metal body.

2. Grounding:

   • Microwave ovens are designed with a grounding system to provide an additional safety measure. The metal chassis of the microwave oven is connected to a grounding wire, which is typically connected to the ground pin of the power plug.
   • In the event of an internal electrical fault that causes the metal chassis to become electrified, the grounding system provides a path for the current to flow safely to the ground, rather than through a person touching the oven.

3. Safety Interlock System:

   • Microwave ovens have a safety interlock system that ensures the high-voltage components are inactive when the door is open.
   • The microwave will not produce microwaves unless the door is properly closed and latched. Opening the door interrupts the power supply to the high-voltage components.

By employing these safety measures, the microwave oven ensures that the high-voltage components, including the secondary winding of the transformer, are isolated from the external circuit and grounded to prevent electrical shock hazards. However, it's important to note that if a microwave oven is damaged or improperly repaired, safety risks may arise, so it's essential to follow proper handling and maintenance guidelines for your microwave.