1. Clip on ammeters are used to measure the high current flowing through bus bar, cable or fuse holders carrying currents.
2. They consist of split core current transformer whose secondary winding is connected to rectifier type moving coil instrument.
3. The primary become conductor, whose current is to be measured. The split core gets aligned by the force of a spring tension.
4. While the core is covered with insulating material. Hence higher current through conductors can be measured.
5. A selector switch is provided to select secondary number of turns which ultimately changes the current range.
6. For measuring current the core is opened by pressing trigger shown and then clipped over the conductor carrying current. The dial will record the current directly.