Which Formula Should I Use for Calculating Power in an AC Circuit?

Thread starter hquang001
Start date Mar 24, 2021
Tags

Ac Ac circuit Circuit Power

Click For Summary

SUMMARY

The discussion centers on the appropriate formula for calculating power in an AC circuit. Participants confirm that the correct formula is P = Vrms.Irms.cosφ, which calculates real power in watts (W). The formula P = V.I is identified as representing instantaneous power in volt-amperes (VA). This distinction is crucial for accurately determining power consumption in AC systems.

PREREQUISITES

Understanding of AC circuit principles
Familiarity with root mean square (RMS) values
Knowledge of power factor (cosφ)
Basic electrical engineering concepts

NEXT STEPS

Research the implications of power factor on energy efficiency
Learn about the differences between real power, reactive power, and apparent power
Explore the use of power analyzers for measuring AC power
Study the effects of harmonics on power calculations in AC circuits

USEFUL FOR

Electrical engineers, technicians working with AC circuits, and students studying electrical power systems will benefit from this discussion.

Mar 24, 2021

hquang001

TL;DR: When the teacher ask me to find real power of an AC Circuit, which formula should i use ?

Should i use P = V.I or P = Vrms.Irms.cosφ ?

Engineering news on Phys.org

Mar 24, 2021

Baluncore

Science Advisor

P = Vrms.Irms.cosφ

Mar 26, 2021

alan123hk

Real or average or active power = Vrms.Irms.cosφ (W)
Instantaneous power = V.I (VA)

Thread 'uA709 op amp compensation'

Most likely this can only be answered by an "old timer". I am making measurements on an uA709 op amp (metal can). I would like to calculate the frequency rolloff curves (I can measure them). I assume the compensation is via the miller effect. To do the calculations I would need to know the gain of the transistors and the effective resistance seen at the compensation terminals, not including the values I put there. Anyone know those values?

View full post »