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Author Topic: "Apparent Power" VS "Maximum Potential Power"  (Read 735 times)
Jr. Member
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Posts: 80
I have a question I hope to understand. Thanks in advanced.


Does Taking Open Circuit Voltage Multiplied by Short Circuit Current give us "Maximum Potential Power" that assumes the output is used 100% efficiently with no losses?  When measuring in DC off a rectifier?

From my research, conventional understands seem to say "The product of Open Circuit Voltage Multiplied by Short Circuit Current should never exceed the input power".

Is this correct?
   
Group: Tech Wizard
Hero Member
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Posts: 1195
I have a question I hope to understand. Thanks in advanced.


Does Taking Open Circuit Voltage Multiplied by Short Circuit Current give us "Maximum Potential Power" that assumes the output is used 100% efficiently with no losses?  When measuring in DC off a rectifier?

From my research, conventional understands seem to say "The product of Open Circuit Voltage Multiplied by Short Circuit Current should never exceed the input power".

Is this correct?

Hi floodrod,

So you mean this situation: you have a coil and a voltage is induced in it by varying magnetic flux and you rectify the AC output of the coil and short circuit the rectified DC output. If this is the setup regarding your question, then on the first part of the question:
     Does Taking Open Circuit Voltage Multiplied by Short Circuit Current give us "Maximum Potential Power"?

my answer would be yes  but note:
1) all the power induced in the coil dissipates in the coil core if there is any and wire resistance and in the rectifier diodes
2) in such setup the measurable AC voltage across the coil is determined by the AC impedance of the coil (which includes the DC resistance too), you can see this as if a generator (i.e. the induction itself) feeds directly a coil and this coil is directly shorted via rectifier diodes.

And on the 2nd part of your question "... that assumes the output is used 100% efficiently with no losses?  When measuring in DC off a rectifier?"

my answer is no because all the induced power is lost in the coil + core and in the diodes. So how can we understand this to be a 100 % efficient case? The "Maximum Potential Power" is dissipated, no useful output power remains.

On this understanding: "The product of Open Circuit Voltage Multiplied by Short Circuit Current should never exceed the input power".
Well, this sounds correct but is this data useful in practice?  I mean your load (that you connect across the DC output of this setup instead of the short circuit) creates a voltage divider with the coil's own impedance, so the induced EMF (i.e. the Max Potential) is divided immediately between the load and the coil in the ratio of their impedances. 
And the voltage measurable across the coil in this case is already a divided part of the Maximum induced Potential.
As you know, maximum power transfer happens when the load impedance (resistance) equals the coil's impedance at the frequency involved. (So in this latter,  matched case, half of the Max Potential remains across the coil and the other half feeds the load.  As you know the short circuit current you mentioned above will also be halved in the matched case).

If I misunderstood your setup and or the questions, please tell.

Gyula
   
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