Voltage indicating control units are generally used in H.V panels.
AC voltage detectors work on the principle of capacitive coupling.
Capacitive coupling is the transfer of alternating electrical signals or energy from one segment of a circuit to the other using a capacitor.
Also known as electrostatic or ac coupling, it uses a coupling capacitor connected between the two circuits in series.
If we connect an ac voltage across the two conductors, an ac current will flow as the electrons are alternately attracted or repelled by the voltage on the opposite plate.
They are not used for measurement or protection but they are used for indication of High Voltage of R, Y, B phase.
Voltage Indicating control unit basically give LED indication of R , Y , B phase.
Voltage Indicating control Unit get 3-phase A.C input signal through capacitive voltage detecting insulator.
So when any one phase or all the 3-phases are live then it is indicated by Red bright LED which fitted on the front panel of indicating unit.
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