What does the cardboard plate in your microwave do?

Your microwave heats your food with a waveguide, which sends energy from the device to your food. When dirt or grease gets to this part, it creates a short circuit. The mica plate is placed in front of this conductor to prevent this. Thanks to its special coating, this plate works well with high temperatures. As a result,, it's no problem when your soup splashes accidentally.

Is the mica plate damaged or have you removed it? If so, don't use the microwave or you'll increase the risk of a short circuit and fire hazard. Unplug the microwave and order a new plate from the manufacturer. Make sure you have the brand and type number, so you can order the right cover plate. You can find the type number on the inside of the door or on the back of the microwave.