Can self induction increase power consumption?

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Discussion Overview

The discussion revolves around the power consumption differences observed in a coil when subjected to direct current (DC) versus alternating current (AC). Participants explore the implications of self-induction in coils and how it affects power consumption in different electrical regimes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes a power consumption of 5W with DC and 5.5W with AC, suggesting that self-induction may play a role in the increased power consumption under AC.
  • Another participant questions the inductance of the coil, the frequency of the AC, and the methods used for measuring current and voltage, indicating that these factors are crucial for understanding the results.
  • A later reply mentions that power dissipation should be the same for DC and RMS voltage under similar conditions, implying that the original question may lack clarity.
  • One participant expresses uncertainty about the relationship between maintaining a constant effective current and the need to increase AC voltage, seeking validation for their reasoning.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as there are multiple competing views regarding the effects of self-induction and the conditions under which power consumption varies between DC and AC.

Contextual Notes

Limitations include a lack of specific measurements for inductance, AC frequency, and voltage sources, which may affect the understanding of power consumption differences.

Jucimar
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Hi folks,

My question relays on the difference of consumption power of a coil when it's on AC and CC regime.

A coild is made of copper wire with air core, aplied on it a CC current of 1 amp, a measure was taked and nottice a 5W of power consumption. Then the power supply is changed to and AC power suplly, now the consumption was about 5,5W. Now the coil was dismaid and it is just a simple wire ( straigh line) and remais on AC power supply. Now the consumption is around 5W again.I have some tought about it but I'm not quite sure. It seems to me that when you a CC regime on a wire, the coil only represent a indcutor it self and after a long time it turn just to be a short circuit, so this can't increase the power.
When i have the coil on AC regime, it creates a self induction made by a opsition to the real currente that pass trough the wire, in that, we need to increase the voltage of the power supply to still with 1 amp (effective).

Can someone help me to understand why this occurs?
 
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Jucimar said:
CC

Do you mean DC?
 
anorlunda said:
Do you mean DC?

Yes, CC for me in Brazil is "Continuos Current" or in USA Direc Currente.
 
Jucimar said:
Then the power supply is changed to and AC power suplly, now the consumption was about 5,5W.
Welcome to the PF.

Do you know what the inductance was of the coil? What frequency was the AC applied? How were you measuring the current and voltage and power? What DC and AC voltages were used? What were the sources of those voltages?
 
berkeman said:
Welcome to the PF.

Do you know what the inductance was of the coil? What frequency was the AC applied? How were you measuring the current and voltage and power? What DC and AC voltages were used? What were the sources of those voltages?

The statement was made in a exam of my college...this data was all about we had...when you do some calculus by ohms law we can see the dc voltage is 5 volts, perhaps that on ac voltage its no simple, the frequency is 60hz... so my think is that to maintain the same currente of 1 amp (effective current) the only when to increase power is to increase ac voltage, makes any sense for you?
 
Power dissipation given the same DC and RMS voltage should be the same. The question is not well-formed, IMO.
 

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