The number of chargers means an automatically controlled electromagnetic device that starts and converts other devices in the same circuit or different circuits to change circuit conditions.
The number of chargers detailed explanation
one
A tool for charging electrostatic dosimeters, such as pocket dosimeters and pocket ionization chambers, when they are in use.
Charging and the number should refer to a certain electrical appliance out of power, but need to use a charger to charge, the specific number of chargers used, that is, the number of chargers.