Basic Concepts related to AC circuit.

-

           

Basic concepts related to AC circuit :-Reactance :-

     Reactance is defined as the opposition produced in ac circuit by reactive element auch as capacitor or inductor.
It is mejores by 'X' and its unit is 'ohm'.

The reactance is devided into two parts:-
  • Inductive reactance (XL).
  • Capacitive reactance (XC). 
  1. Inductive reactance (XL):-
         Inductive reactance is defined as opposition produced in ac circuit by inductor.
                     XL = 2ฯ€FL
Its unit is ohm
2. Capacitive reactance (XC) :-
         Capacitive reactance is defined as opposition produced in ac circuit by capacitor.
                    XC  = 1/2ฯ€FC
It's unit is also 'ohm'.

Impedance :- 
    Impedance is defined as opposition produced by combination of resistance and reactance in ac circuit.
It's unit is 'ohm'
                    Z  = √ R^2 + X^2


Types of power :-
  1. Real or true or active power (P).
  2. Reactive or imaginary power (Q).
  3. Appearent power (S).
1. Active power (P):-
    It is defined as product of voltage, current and cos of angle between voltage and current.
                    P = V×I×cosฮฆ
It's unit is watt or kW.

2. Reactive power (Q):-
     It is defined as the product of voltage, current, and sin of angle between voltage and current.
                    Q = V×I×sinฮฆ
It's unit VAR or kVAR.(volt ampere reactive )

3. Apparent power(S) :-
     It is defined as the product of voltage and current.
                    S = V×I
It's unit is VA or KVA.

Power factor:- 
    It is defined as cosine angle between voltage and current.
    Power factor = real power /apparent power
                 Power factor = cosฮฆ

Admittance (Y):-
      Admittance is defined as the reciprocal of impedance or it is combination of conductance and susceptance.
                    Y = 1/Z
Its unit is mho or Siemens 

Conductance(G):-
      It is defined as the ratio of resistance to square of impedance.
                   G = R/Z^2
Its unit is mho or Siemens.

Susceptance(B):-
     The susceptance is defined as define as ratio of reactance to square of impedance.
                  B = X/Z^2


Comments

Post a Comment

Popular posts from this blog

Main parts of transformer.

-
Image
Transformer :-     Transformer is static device or which transfers AC power from one circuit to another without change in frequency. The main parts of transformer are as follows:-  Three limb core. LV winding. HV winding. Tapped winding. Tap leads. LV bushings. HV bushings. Frame. ON load tap changer. Conservator tank. Radiator. Breather. Test valve. Temperature and oil level indicators. Buccholz relay.   We transformer there is no change on frequency from No load to full load. The voltage level can be changed either it stepped up or down according to need. The transformer is very crucial device in electrical system now days, Without it we can't run our system efficiently. There are two main type of transformer:-  1. Power transformer. 2. Distribution transformer. Other some special types of transformer are there used for special purpose only like, isolation transformer, instrument and welding transformer etc.
Read more

Electrical terms.

-
Image
Basic electrical terms. Alternating Current (AC)  — An electric current that reverses its direction many times a second at regular intervals. Ammeter  — An instrument for measuring the flow of electrical current in amperes. Ammeters are always connected in series with the circuit to be tested. Ampacity  — The maximum amount of electric current a conductor or device can carry before sustaining immediate or progressive deterioration. Ampere-Hour (Ah)  — A unit of measure for battery capacity. It is obtained by multiplying the current (in amperes) by the time (in hours) during which current flows. For example, a battery which provides 5 amperes for 20 hours is said to deliver 100 ampere - hours. Ampere (A)  — A unit of measure for the intensity of an electric current flowing in a circuit. One ampere is equal to a current flow of one coulomb per second. Apparent Power  — Measured in volt-ampers (VA). Apparent power is the product o...
Read more

Why induction motor is self starting and synchronous motor ia not?

-
Image
Q - Why induction motor is self starting and synchronous motor is not ? Ans_    A 3- phase supply given to the armature of Induction Motor produces a rotating magnetic field. This rotating magnetic field rotates at synchronous speed Ns = (120xf)/P This rotating magnetic field links to the rotor coils and induces voltage which in turn produces current in the rotor. The current carrying rotor being placed in a magnetic field experiences a torque and hence begins to rotate in the direction of rotating magnetic field. Thus we see that Induction Motor is self-starting. It does not require nay external mean to rotate. Now we consider a 3-phase synchronous motor. A 3-phase supply is given to the armature of Synchronous Motor, produces a rotating magnetic field. However, in this case, the rotor has its own field produced by a DC current flowing through the rotor winding. This rotor field tends to align itself along with the rotating magnetic field produced by the stator i.e. armature ...
Read more