In an Energy meter, how is the shunt electromagnet connected in driving System?

Question

Question

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HSSC ALM Previous Paper 1 (Held On: 14 March 2020 Shift 1)

The shunt electromagnet's coil is connected with the supply and carries current inversely proportional to the resistance.
The shunt electromagnet's coil is connected with the series magnet and carries current proportional to the resistance
The shunt electromagnet's coil is connected with the supply and carries current proportional to the supply voltage
The shunt electromagnet's coil is connected with the series magnet and carries current inversely proportional to the supply voltage

Answer 1

Driving system of Energy meter:

In this system there are two silicon steel laminated electromagnet.
The upper magnet called shunt magnet it carries a voltage coil consisting many turns of thin wire which connected to supply voltage so it's behave like a potential coil. Voltage coil is connected to the supply voltage.
The lower magnet called series magnet it carries the two current coils consisting of few turns of thick wire and behave like a current coil. Current coils are connected in series with the circuit and load current passes through it.

F1 Jai 21.11.20 Pallavi D7

Key Points

Component	Construction
Driving system	In this system there are two silicon steel laminated electromagnet Upper magnet → Shunt magnet → behave as potential coil Lower magnet → series magnet → behave as current coil
Moving system	In this system a thin aluminum disk placed in the gap between the two electromagnets and mounted on a vertical shaft which is free to rotate.
Registering system	It registers the number of rotation of the disk which is proportional to the energy consumed directly in kilowatt-hour
Braking system	This system has a permanent magnet called brake magnet. It is located near the disk so that eddy currents are induced and braking toque to the disk.