# Pspice AC analysis of an equivalent mono phase circuit

#### Venia

Joined Sep 17, 2020
3
Hi! I've solved and simulated on PSpice a balanced three phase circuit and now I'm considering the equivalent mono phase circuit. I've already done the transient analysis and I'd like to know if I can run other kind of analysis such as an AC SWEEP/NOISE (to simulate the behaviour of the system at different frequencies) or if I can consider the equivalent mono phase circuit (which is a LTI circuit with just resistors and inductors) to calculate the frequency response. Does it make sense to you? Any help would be appreciated!

#### Papabravo

Joined Feb 24, 2006
17,310
Everything you do with the simulator has some value in terms of enhancing your understanding of reality. Especially if the results deviate from your observations.
Let me ask you a return question. Does the mono phase power distribution system have any significant capacitive load? How would you know if it did? What happens if the load becomes primarily inductive? How would you know? Part of the answer lies in the phase relationship of the current and voltage waveforms.

#### Venia

Joined Sep 17, 2020
3
Thanks for your replay! In circuits with primarily inductive loads, current lags the voltage so observing the waveforms I can understand if there is a capacitive load (there must be a delay angle). Maybe simulating the circuit at different frequencies can help me. I presume that if frequency is higher, current is lower so with the simulation I may verify that. Am I right? I don't understand what's the sense of calculating the frequency response of the equivalent mono phase, in this case and if I can do that.

#### Papabravo

Joined Feb 24, 2006
17,310
Thanks for your replay! In circuits with primarily inductive loads, current lags the voltage so observing the waveforms I can understand if there is a capacitive load (there must be a delay angle). Maybe simulating the circuit at different frequencies can help me. I presume that if frequency is higher, current is lower so with the simulation I may verify that. Am I right? I don't understand what's the sense of calculating the frequency response of the equivalent mono phase, in this case and if I can do that.
In AC power distribution systems the frequency is very tightly controlled and the load current is NOT dependent on the line frequency. Using RMS values for voltage and current and Ohm's law tells you how voltage, current and resistance are related. when the load is purely resistive the voltage and current will be in phase. with any kind of reactive load there will be some amount of lead or lag between the two, but the RMS value remains the same.