Avr

Discussion in 'AVR' started by dimper129, Sep 13, 2007.

1. dimper129Member

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Hi!

Attached is the circuit diagram of Automatic Voltage Regulate AVR.

In the figure, do we need the wire of different cross-section area for different coils (i.e. coil1 (red), coil2 (green), coil3 (blue) and coil4 (cyan)) because of the different amount of current that will be pass through them.

Can anybody help me to solve this matter please

Thanks.

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2. Nigel GoodwinSuper ModeratorMost Helpful Member

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No, use all large wires, the difference in current is far too small to attempt using thinner wires for the higher voltages - and thicker wires mean less loss anyway.

3. dimper129Member

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thank you for the replay!

i have still one question in my mind.
if we put 220W load on the AVR
will the the current in the coil be 1 Amp or will it be the sum of currents (input current+ output current) in the input loop and the output loop?

Thanks!

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5. ecerfoglioNew Member

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In an ideal transformer (or autotransformer like your example) the aparent power (VA) at the output is the same that the one at the input.

(in a real transformer the transformer's losses make the input power (both real power in W and aparent power in VA) slightly higher than the output one, but you may use the ideal transformer formulae as an aproximation.

You can find the aparent power (VA) as voltage times current (eg: 220 V x 2 A = 440 VA).

So the input current will be aproximately

input current = output current x output voltage / input voltage

No, the real power is Voltage times current times power factor.

The power factor (or cos fi) is allways less than one (or at least equal to one if the load is a pure resistor).

To measure real power (W) you need a wattmeter, which measures voltage and current simultaneusly.

To measure aparent power (VA) you only need a voltmeter and ammeter.

If the load is an electronic one (like a PC), you need an ammeter that reads true RMS values as the current will have a high harmonic content and a "simple" ammeter or DMM will give a large error.

Last edited: Sep 18, 2007