transformers electronic notes pptx in depth
- 1. TRANSFORMERS
- 2. An electrical transformer is a static device which is used for the transformation of AC electrical signal in one circuit to the electrical signal of the same frequency in another circuit with a little loss of power
- 3. How do transformers work? The operation of transformer mainly works on the principle of mutual inductance between two circuits linked by a common magnetic flux. A transformer is basically used for transformation of electrical energy. Transformers consist of types of conducting coils as primary winding and secondary windings. The input coil is called the primary winding and the output coil is called the secondary winding of the transformer
- 4. The windings are linked by an alternating magnetic field created in the soft-iron core of the transformer. Transformers waste very little power so the power out is almost equal to the power in. The primary coil and the secondary coil posses high mutual inductances. If one of the coils is connected to the source of alternating voltage, then an alternating flux will set up in the laminated core. This flux gets linked up with the other coil and an electromagnetic force is induced, as per Faraday’s law of electromagnetic inductance. e = M di/dt Where e is induced EMF M is mutual inductance If the second coil is closed then the current in the coil is transferred from primary coil of the transformer to the secondary coil.
- 5. Ideal power equation of transformer If the secondary coil is attached to a load that allows current to flow in the circuit, electrical power is transmitted from the primary circuit to the secondary circuit. Ideally, the transformer is perfectly efficient; all the incoming energy is transformed from the primary circuit to the magnetic field and into the secondary circuit. If this condition is met, the incoming electric power must equal the outgoing power: Giving the ideal transformer equation
- 6. Different Types of Transformers classified based on different criteria like function, core, etc. FUNCTIO N CORE BASED ON WINDINGS ARRANGEME NT OF THE COILS ACCORDING TO USE TYPE OF COOLING Step-up Core type Two winding Cylindrical type Power transformer Natural cooling Step-down Shell type Single winding Disc type Distribution transformer Oil immersed natural cooled Three winding Oil immersed natural cooled with forced oil circulation
- 7. Classification according to function: Step-Up Transformer A step up transformer is the one in which the primary voltage of the coil is lesser than secondary voltage. A Step-up transformer can be used for increasing voltage in the circuit. Step-down transformer is used for reducing the voltage. The type of transformer in which the primary voltage of the coil is greater than the secondary voltage. Most power supplies use a step-down transformer to reduce the dangerously high voltage to a safer low voltage.
- 8. The ratio of the number of turns on each coil, called the turn’s ratio determines the ratio of the voltages. A step-down transformer has a large number of turns on its primary (input) coil which is connected to the high voltage mains supply, and a small number of turns on its secondary (output) coil to give a low output voltage. TURNS RATIO = (Vp / Vs) = (Np / Ns) Where, Vp = primary (input) voltage Vs = secondary (output) voltage Np = number of turns on primary coil Ns = number of turns on secondary coil Ip = primary (input) current Is = secondary (output) current.
- 9. POTENTIOMETERS A potentiometer (also known as a pot or potmeter) is defined as a 3 terminal variable resistor in which the resistance is manually varied to control the flow of electric current. Principle of potentiometer: When a steady current flows through a wire of uniform cross section the potential difference of unit length of the wire is constant throughout the length of the wire across any two points if the wire is directly proportional to the length of the wire.
- 10. advantages Used to measure internal resistance More sensitive compared to voltmeter The accuracy of the potentiometer can be increased by increasing the length of the wire