Transformer as a Constant Flux Device ( Transformer on LOAD )

Transformer ON Load

• When the supply voltage V₁ is given to the transformer primary winding, primary current I₁ flows through the winding which produces maximum flux F_m in the core. 

Transformer on NO Load

• When the supply voltage V₁ is given to the transformer primary winding, the no load current I₀ flows through the primary winding. This current sets up flux in the core. 

EMF Equation of the Single Phase Transformer

EMF Equation

• When an alternating voltage V₁ is applied to the transformer primary side, an alternating flux will set up in the core which links both primary and secondary winding.  

Principle of Transformer

• The transformer is a static device which transfers electrical power from one side to other side without change of frequency. 
• One or more winding of transformer are linked with common magnetic circuit. 

Static and Dynamic Characteristics of the SCR

Characteristics of SCR

In this post, static and dynamic characteristic of SCR is given. The static characteristic is related to voltage – current relation of the SCR during on state whereas the dynamic characteristic is related to current and voltage across SCR during its ON state and OFF state.

Structure, Equivalent circuit and Working of the SCR

• The full form of the SCR is silicon controlled rectifier. 
• It is a three junction, three terminal and four layer type PNPN semiconductor device. The terminals are anode (A), cathode (K) and gate (G).
• It allows current flow only one direction so it is called as unidirectional device. 

Speed Control of the DC Series Motor

• The speed of the DC Motor is related to following equations

         N α E_b / Ф

         N = K ( V – I_aR_a ) / Ф

• Therefore the speed of the DC Motor is controlled by varying

Torque and Output Power Equation of the DC Motor

• The term torque means ‘Turning movement of the force about an axis.’

        T = F × r Newton – meter

        Where T = Torque

                   F = Force in Newton

                    r = Radius in Meter

UJT As Relaxation Oscillator

• The UJT is often used in the timing and triggering circuits. 
• Figure A shows the circuit diagram for the UJT relaxation oscillator.
• When the switch S is kept closed, the capacitor C is charged through resistance R towards voltage V_DC. 

Structure, Working and Characteristic of the UJT

• The full form of the UJT is uni junction transistor. 
• It is a single PN junction semiconductor switching device. 
• It has three terminals : base 1 ( B₁ ), base 2 ( B₂ ) and emitter. The structure and symbol of the UJT is shown in the Figure A.

Structure, Working & Characteristic of the Triac

• The triac is a three terminal bidirectional switching device. 
• It is an AC switch which can conduct on both of the alternating cycle ( Positive as well as Negative ). 
• The triac word is combination of two words TRI and AC. 

Working and Characteristic of the Diac

Structure and Symbol

• The DIAC is a bidirectional, two terminal semiconductor device which can be turned on by either ( Positive or Negative ) polarity of alternating supply voltage. 

What is Back Emf ?

• As soon as the armature starts rotating, dynamically induced emf is produced in the armature conductors. 
• The direction of induced emf is found by Fleming's Right hand rule
  

Working Principle of DC Motor

Electrical Motor

An Electric motor is a machine which converts electrical input energy into mechanical output energy.   

• When a current carrying conductor is placed in magnetic field, it