Concept of AC single phase circuits.

AC CIRCUIT

                 AC voltage applied to a circuit call AC circuits. The Flow of electrons in AC circuits is bidirectional.AC circuits depends on load connected in it are four types. 1. Load as a resistance(R) 2.Load as a capacitive(C) 3. Load as an inductive (L) 4. Load as a (R-L-C)

1. Load as a resistance(R): 

Restive single phase AC circuit 

In ac circuit load is a resistance, the voltage and current are in same phase shown in figure below i.e. maximum value of voltage is reached at the same instant as peak current. In Phasor diagram the angle between voltage (V) and current (I) is zero.

(A)   v=Vm sin ωt value of alternating voltage.

(B)   i= Im sin ωt where Im= Vm/R value of alternating current.

(C)   P= Vm Im/2*(1-cos2ωt) Instantaneous power.

(D)  P= Vm/2 * Im/2 Average power.

2.Load as a capacitive(C): 

Capacitive single phase AC circuit

 In ac circuit which has only a capacitor is a device stored the charge the phase difference between voltage and current is 90 degree i.e. current lead the voltage by 90 degree in this image the peak value of voltage at 90 degree before the current reached the maximum in zero degree. In Phasor diagram the angle between voltage (V) and current (I) is 90 degree i.e. current leads the voltage by 90 degree.

(A) v=Vm sin ωt ,value of alternating voltage.

(B)  i= Im sin (ωt+ 90 degree), where Im=ωC Vm, value of alternating current.

(C)  P= Vm Im/2 *sin2ωt, Instantaneous power.

(D)  P= 0, Average power.

3. Load as a Inductive (L): 

Inductive AC single phase circuit 

If AC circuit purely inductive (a coil of wire wound on ferromagnetic material)  the phase difference between voltage and current again 90 degree but current legging 90 degree behind the voltage i.e. voltage reached the maximum or peak 90degree after the current reach the peak. In Phasor diagram the angle between voltage (V) and current (I) is 90 degree i.e. current lags the voltage by 90 degree.

(A)   v=Vm sin ωt ,value of alternating voltage.

(B)   i= Im sin(ωt- 90 degree),where Im= Vm/ωL,value of alternating current.

(C)   P= - (Vm Im/2* sin2ωt),Instantaneous power.

(D)   P= 0, Average power.

4. Load as a Restive, capacitive and inductive (R-L-C): 

R-L-C single phase circuit

Such type of circuit called RLC circuit. The overall resistance of the RLC circuit is known as impedance (Z). In this phasor diagram resistance along the X- axis and Inductive reactance (XL), Inductive capacitance (XC) along y –axis   90 degree phase difference to the resistance. Between Inductive reactance (XL) and Inductive capacitance (XC) phase difference is 180 degree opposite each other. The value of impedance Z is √(R^2 )+(XL-XC)^2 according to ohms law V=IZ. When (XL)> (Xc) the circuit is inductive, (XL) < (Xc) the circuit is capacitive (XL) = (Xc) the circuit is purely resistive.