hi friends in this video we are going to see how a transformer is look like if I am not loading it that means if I am not providing any load at the secondary side from this we will be seeing how the equivalent circuit of a transformer will look like and phasor diagram of that so I will draw this transformer structure once again to the core this is primary winding because I am giving supply to this coin and this is secondary winding right now it is not loading so it is opening this is primary voltage v1 which will give rise to primary current i1 this primary current i1 is flowing through this winding which will give rise to magnetic flux which will pass through this core this diagram flux can be determined by right hand thumb rule it says holes are windings such a way that curved finger will vapor then the direction of current then outstretched thumb will give you direction of flux so this will be the direction of flux fine now this flux flies linked with this winding having N 1 terms will give rise to EMF E 1 maximum flux will pass through this code but some amount of flux is complete its path outside the core which we call as a leakage flux now same-sex Phi is linked with this winding and here also some amount of flux is going to be wasted in air like this and maximum part of the flux will linked with this winding having n to number of turns which will give rise to EMF E - now I am tipping this winding open circuited hence current flowing over here I to equal to zero because of which voltage which we call the terminal voltage v2 is same as secondary side induced EMF E - so this is what happening at no load there will be i1 current the job of i1 current is like this so this I 1 I will call as no lower primary current a zero very small value this eyes ero so two purposes or you can say it has two components first component so i0 has two components if you see properly there are two things happening over here one is magnetic flux is getting generated and which is passing through this core because of which magnetic losses will appear and those losses are nothing but hysteresis and eddy current so these are the power losses so some amount of current and some representation of this losses as a resistance will be there so current i0 has two so these core losses or you can say this iron losses and secondly flux Phi need to be created so the job of i0 is generation of magnetic flux the component which is responsible for generation of magnetic flux is called as magnetizing component of isay row we denote it as I mu magnetizing component of a zero is responsible for generation of magnetic flux and second is some amount of current should take care of core losses happening inside the core so component which is responsible for magnetic losses so what are the magnetic losses happening histories and eddy-current along with the magnetic losses there will be some primary side copper losses so the component which is responsible for magnetic losses and primary winding I square R losses is called as Cole offs component of a zero we denoted it as IC so core loss component of current is responsible for taking care of losses happening inside the code now suppose I want to analyze this circuit further it is not easy that every time I should have this diagram and then writing all the core passing through code is a flux current i1 and all that so better we can symbolically represent this so let's check how we are going to write equivalent circuit of a transformer so I will start from the primary side so primary side there are number of turns so obviously primary side or primary winding resistance will be there represented as R 1 so it will be like this now some amount of flux is getting licked in air in account of that I will represent that as leakage reactance at the primary side and there are two components always present one is this magnetizing component which is responsible for production of magnetic flux Phi and second component is this core loss component which will sell losses at no load or even if a transformer is loaded these two parts will always be there because we need a magnetic flux and because of that losses will be occurring so this two parts can be represented in a transformer like this so this is a primary side of a transformer why it is called as the primary because here I am going to connect a supply now at the secondary side I am having this winding where resistance is present and some leakage flux leakage reactance will be consider so the secondary side it will be secondary winding resistance and secondary side leakage reactance so this is equal circuit diagram at no load once again we will see this diagram this is V 1 voltage applied primary winding resistance primary winding leakage reactance core loss resistance magnetizing reactance this is no load primary current core loss component of a zero magnetizing component of i0 here secondary winding resistance secondary winding leakage reactance N 1 number of primary turns into number of secondary turns even primary side induced EMF E 2 secondary side induced EMF right now I 2 is a secondary current which is 0 and V 2 V 2 is the terminal voltage of a transformer so let us list out all this V 1 primary voltage our one primary winding resistance x1 primary leakage reactance Ivo is no lower primary current I see it is a core loss component of Phi zero I'm ooh it is magnetizing component of a 0rc core loss resistance XM magnetizing reactance II won is primary induced e-m-f and one number of primary winding turns our two secondary winding resistance x2 secondary leakage reactance n to number of secondary winding turns e to secondary induced e-m-f and finally v2 is the terminal voltage or secondary voltage now this is a h1 circuit diagram of a transformer at no load let's draw its phasor diagram so I will start with flux Phi this plus five is responsible for production of a1 and a2 primary side and secondary side induced EMF which will lag 5 by 90 degree that we have seen already while deriving EMF equation of a transform 1 so e1 and e2 will be like this I will consider n1 number of turns are less than that of n2 hence II 1 is less than e 2 now this works v is produced because of IMU so i mu is nothing but magnetizing component of a zero so the current which is the responsible for production of flux phi will come in phase with flux phi so this is i mu i mu is the current passing through this inductor whose voltage will be e 1 actually by Lenz's law it should be minus e1 that we have already seen so what if we want over here II 1 and its opposite phases is required which is minus e1 so equal and opposite to this e 1 will be minus e1 which will be like this now this minus e1 is the voltage across this resistance RC so I see will be in phase with minus e1 because for pure resistance voltage and current are in phase so this will be IC and we have seen over here eysie ro is the Knoller primary current which is nothing but addition of IC and IB obviously is the phasor aeration so if I add I see and I mu I will get current i0 like this which is no load primary current so no load primary current will pass through these two elements are 1 and X 1 so if it is pass through R 1 it will give rise to a voltage drop a 0 R 1 in phase or parallel to y 0 so parallel to I 0 I will draw a vector from tip up minus e1 like this same current i0 will be passing through this x1 giving rise to a voltage drop eyes ero X 1 which will be 90-degree leading for this phasor so 90-degree leading will be like this so this is 90 degree now if you see properly this circuit phasor addition of minus e1 is 0 X 1 and a 0 R 1 will be nothing but primary voltage v1 so phasor addition of minus e 1 a 0 R 1 either x1 will be nothing but this voltage which is primary voltage v1 so v1 is the primary voltage and a zero is no lower primary current angle between them is Phi zero no load phase angle so here we develop a phasor diagram based on the current circuit of a transformer at no load this is required because in subsequent videos we are going to see phasor diagrams of a transformer when it is loaded at that time as I said earlier whether transformer is loaded or not this part of equivalent circuit will always be there because we need to produce a flux and if flux is getting produced there will be core losses happening hence we always get this part of equivalent circuit diagram of a transformer whether it is loaded or not thank you