This kind of motor is called synchronous motor, and there are many gears in it to form a speed change device. In order to meet the needs of different places, manufacturers of this kind of motor produce synchronous motors with different speed ratios. There are 3 revolutions per minute, 5 to 50 revolutions per minute, and all kinds of specifications are available.
When purchasing this kind of motor, microwave oven manufacturers can use it as long as it is within the allowable range of their designed products.
As long as the turntable of your microwave oven can rotate, you can use it safely.