Clamp meters are divided into mechanical pointer clamp meters and digital clamp meters. Its biggest advantage is that it can measure the current in the line without disconnecting the line to be measured. The current multi-function clamp meter also carries test leads and other voltage resistance gears, and can also be used as a multimeter, and the clamp current meter is also divided into pointer type and digital type, which are roughly the same as the multimeter classification, but the clamp meter head has a transformer, so it is more troublesome to carry.