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Similar to Unit3 AC Series Circuit-RL, RC, RLC.pptx
Unit3 AC Series Circuit-RL, RC, RLC.pptx
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- 2. Objectives • Describe therelationship between current and voltage in an RL circuit • Determine impedance and phase angle in a Series RL circuit • Analyze a series RL circuit • Determine power in RL circuits
- 3. Circuit Diagram Let VRand VL be the voltage drop across resistor and inductor
- 4. Phasor Diagram • Step-I. Take current phasor as reference and draw it on horizontal axis as shown in diagram. • Step- II. In case of resistor, both voltage and current are in same phase. So draw the voltage phasor, VR along same axis or direction as that of current phasor. i.e VR is in phase with I. • Step- III. We know that in inductor, voltage leads current by 90o, so draw VL (voltage drop across inductor) perpendicular to current phasor. • Step- IV. Now we have two voltages VR and VL. Draw the resultant vector(V) of these two voltages. Such as, and from right angle triangle we get, phase angle
- 5. Waveform • In caseof pure resistive circuit, the phase angle between voltage and current is zero and in case of pure inductive circuit, phase angle is 90o but when we combine both resistance and inductor, the phase angle of a series RL circuit is between 0o to 90o.
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- 7. Power • Instantaneous poweris given by, Average Power = 𝑃𝐴𝑣𝑔 = ∫𝑃𝑖𝑛𝑠𝑡 =𝑽𝒎𝑰𝒎/𝟐 cosΦ = (𝑽𝒎/√𝟐)(𝑰𝒎/√𝟐) cosΦ = 𝑉𝑅𝑀𝑆 𝐼𝑅𝑀𝑆 cosΦ P = V I cosΦ
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- 12. Summary • Total currentin an RL circuit always lags the source voltage • In an RL circuit, the impedance is determined by both the resistance and the inductive reactance combined • The impedance of an RL circuit varies directly with frequency
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- 14. Objectives • Describe therelationship between current and voltage in an RC circuit • Determine impedance and phase angle in a Series RC circuit • Analyze a series RC circuit • Determine power in RC circuits
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- 16. Phasor diagram • Step-I. Take current phasor as reference and draw it on horizontal axis as shown in diagram. • Step- II. In case of resistor, both voltage and current are in same phase. So draw the voltage phasor, VR along same axis or direction as that of current phasor. i.e VR is in phase with I. • Step- III. We know that Capacitor, voltage lags current by 90o, so draw VC (voltage drop across Capacitor) perpendicular to current phasor. • Step- IV. Now we have two voltages VR and VC. Draw the resultant vector(V) of these two voltages.
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- 21. Summary • Total currentin an RC circuit always leads the source voltage • In an RC circuit, the impedance is determined by both the resistance and the Capacitive reactance combined
- 22. RLC Series Circuit Mrs.M R Yashwante MMIT Lohgaon
- 23. Objectives • Describe therelationship between current and voltage in an RLC circuit • Determine impedance and phase angle in a Series RLC circuit • Analyze a series RLC circuit • Determine power in RLC circuits
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- 25. Phasor Diagram XL˃ XC • Step- I. Take current phasor as reference • Step- II. Draw the voltage phasor, VR along same axis or direction as that of current phasor. i.e VR is in phase with I. • Step- III. We know that in inductor, voltage leads current by 90o, so draw VL (voltage drop across inductor) perpendicular to current phasor. Vc lags current by 90o • Step- IV. Draw the resultant vector VL and Vc along VL • Step- I. Draw the resultant vector (VL –Vc) & VR
- 26. Phasor Diagram XL˃ XC • If the inductive reactance is greater than the capacitive reactance, i.e XL > XC, then the RLC circuit has lagging phase angle • It behaves like inductive circuit
- 27. Phasor Diagram XL< XC • if the capacitive reactance is greater than the inductive reactance, i.e XC > XL then the RLC circuit have leading phase angle • It behaves like capacitive circuit
- 28. Phasor Diagram XL= XC • Step- I. Take current phasor as reference • Step- II. Draw the voltage phasor, VR along same axis or direction as that of current phasor. i.e VR is in phase with I. • Step- III. We know that in inductor, voltage leads current by 90o, so draw VL (voltage drop across inductor) perpendicular to current phasor. Vc lags current by 90o • Step- IV. Draw the resultant vector VL and Vc is zero • Step- I. Draw the resultant vector is only VR
- 29. Phasor Diagram XL= XC • It behaves like pure Resistive circuit • It is series resonance • Impedance is minimum. Z= R • Current is maximum I =V/R • Power factor is unity
- 30. Resonant frequency At acertain frequency called resonant frequency, the inductive reactance of the circuit becomes equal to capacitive reactance which causes the electrical energy to oscillate between the electric field of the capacitor and magnetic field of the inductor. At resonant frequency, XL = XC
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- 32. Definition • Admittance ofa circuit is defined as the reciprocal of impedance • Denoted by Y • Unit --Mho(℧) or siemens (s)
- 33. Importance • In parallelAC circuits it is more convenient to use admittance, to solve complex branch impedances especially when two or more parallel branch impedances are involved
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