UPDATE : 2017-09-07
Currently, most ammeters use
mutual inductors. Their working principle is: according to the principle of
electromagnetic induction, the ammeter can produce electromagnetic fields on
current coil and voltage coil and form driving torque on the aluminum disk once
powered on and its driving gear drives its counter to count. The higher the
current voltage, the higher the driving torque, and the faster the counting,
the more the electricity is used.
According to new
stipulations of state grid, all new smart ammeters must be equipped with
electricity stealing prevention functions. The electricity stealing prevention
scheme is provided for new smart ammeters as thus, i.e. use Hall magnetic
sensors to detect the electricity stealing magnetic fields applied by stealers
from the outside. When anyone tries to apply an external magnetic field to
destroy counter of the ammeter, the Hall sensor can detect such external
magnetic field and the anti-stealing system can act at once to play the role of
electricity stealing prevention.
As we cannot foresee from
which magnetic pole the stealer tries to steal electricity, non-polar Hall
switching circuit with micro power consumption or non-polar conventional Hall switching
circuit shall be used.
LiBrave is now working on
non-polar conventional Hall switching circuit to meet market demands.