3. TRANSFORMER
• Transformer is a device used for changing low alteration voltage
at high current. It changes the alteration voltage without the loss
of energy
4. PRINCIPLE
• It works on the principle of electromagnetic mutual
• ELECTROMAGNETIC MUTUAL INDUCTION-
When the current is provided to the primary winding it behaves as
electromagnet due to this, the EMF induced in the area having magnetic
field lines to primary winding.
Vs =Ns.dɸ/dt
Vs= secondary winding voltage
Ns= secondary winding turns
5. CONSTRUCTION
i. Laminated core – Core are designed not to have current in it.
But still there is a leakages current or the eddy current in it to
minimize these current the cores are laminated.
ii. Winding – Made up of copper or aluminum coated with very
thin layer of insulation.
iii. Tank – The main function of conserstor tank of transformer is to
provide adequate space for expansion of oil inside the
transformer. It is usually cylindrical or cubicl
6. • ISOLATION – It is provided by using synthetic oil between core
and tank.
• BREATHER – When the temperature changes occurs in
transformer insulation oil, the oil expands or contracts and there
an exchange of air also occurs when transformer is fully loaded.
When transformer gets cooled the oil level goes down and air
gets absorbed within.
7. TYPES OF TRANSFORMER
• The transformer are divided into three types-
a. Static transformer
b. Variable transformer
c. Auto transformer
8. 1. STATIC TRANSFORMER
• The static transformer is based on the principle of electromagnetic induction and is
used to alter voltage of an alternating current and to render the current Earth free.
• Construction – It consist of two coils of insulated wire, the primary and the
secondary coils, wound on a laminated soft iron core, the iron coil
are completely insulated from each other and one usually contains more turns of wire
than the other. The frame is often rectangular in the shape and the coils may be
wound on opposite bars of the frame or one on top of the other on a central bar.
9.
10. WORKING OF THE STATIC TRANSFORMER
• An alternating current is passed through the primary coil and sets up a
varying magnetic field which cuts the secondary coil and induced on EMF in
it is essential that the primary varies in intensity otherwise there is no
movement of the magnetic field relative to the conductor and no EMF is
induced in the secondary coil. There is no electrical conduction between the
primary and the secondary coils, the energy being transmitted from one to
the other by electromagnetic field and is made of soft iron as thin material is
easily magnetized and demagnetized. It is laminated to prevent eddy current.
11. TYPES OF STATIC TRANSFORMER
I. Step-up transformer
II. Step-down transformer
III. Even ratio transformer
12. STEP-UP TRANSFORMER
• If the number of turns in the secondary are more than that the as the
primary, the voltage developed in the secondary will be increased or stepped
up such a device is called as step-up transformer.
13. STEP-DOWN TRANSFORMER
• If the secondary coil has fewer turns than the primary then the EMF or voltage in the
secondary will be less than in the primary.
14. EVEN RATIO TRANSFORMER
• If the number of turns in the primary and secondary coils is the same as that
of the secondary such as the device is called even ratio transformer.
15. VARIABLE TRANSFORMER
• It consist of primary and secondary coil, but is constructed so that one of them can
be altered in length. The primary coil has a number of tapings taken from it and a
movable contact can be made on any one of these by turning a knob the effect of
decreasing the number of turns in the primary coil relative to the secondary is to
cause a step-up voltage in the secondary coil. In this way a very crude control of
voltage is obtained.
16.
17. AUTO TRANSFORMER
• An auto transformer consist of a single coil of wire found contact points
coming from it can be used as a step-up or step-down transformer. When
used as the step-up, CD is the primary coil and AB is the secondary coil.
When the step-down, AB is the primary and CD is the secondary coil.
Although the autotransformers works on the disadvantage that, it allows only
a small step-up and does not render the current Earth free. It is used in the
starter circuit of ultraviolet lamp to strike the arc in the lamp.
18.
19. USES
• In most cases appliances are manufactured to work under some specific
voltage. Transformer are used to adjust the voltage to a proper level.
• The transformer are the basic components for the transmission of electricity.
• Transformer is used to increase the voltage at the power generating station
(step-up) and used to decrease the voltage (step-down) for house hold
purpose
• By increasing the voltage the loss of electricity in the transmission purpose is
minimized.
