U2 is connected to V 1, a capacitor is connected between V2 and U 1, the live wire of the power supply is connected to U 1, and the zero line of the power supply is connected to U2. The motor capacity is less than 40W, with two micro-capacitors, and 60~ 120W with four micro-capacitors. Angle grinder, also known as grinder or disc refiner, is an abrasive tool for cutting and polishing FRP. Angle grinder is a portable electric tool that uses FRP for cutting and polishing. Mainly used for cutting, grinding and brushing metal and stone. Electric angle grinder is used to grind, cut, remove rust and polish metal components by using high-speed rotating thin plate grinding wheel, rubber grinding wheel and steel wire wheel. Angle grinder is suitable for cutting, grinding and brushing metal and stone, and water is not allowed during operation. Guide plates must be used when cutting stone. For models equipped with electronic control devices, grinding and polishing operations can also be carried out if appropriate accessories are installed on such machines.