Voltage transformer

This device is very common used in electronic/electrical industry in the world.Start from small transformer for electronic equipment until big transformer for High voltage  power transmission.Transformer is important device in our life every day.

The main purpose of voltage Transformer is a changing or “transform” the value of voltage ( single or three phase ) .

It can step up the voltage value ; example : 110VAC step up to 240VAC ( For power supply usage )  or 11 kVAC step up to 33 kVAC ( for power transmission).

It also can step down the voltage value ; example : 240 VAC step down to 24 VAC ( For rectifier power supply) or 11 kVAC step down to 415 VAC ( For Consumer power supply ).

What is a Voltage Transformer?

 

Voltage Transformer  CANNOT :-

• Convert AC to DC or otherwise
• Change the current and voltage of DC (Direct Current )
• Change the Frequency ( Hz ) of AC supply

Transformer description

Basically a transformer have a two(2) principals :-

1) The electric current can produce the magnetic field.

2) The changing of magnetic field within a coil of wire induce the voltage across the final of coil.

A simple transformer consists of two electrical conductors called the primary winding and the secondary winding.

If a time-varying voltage is applied to the primary winding of turns, a current will flow in it producing a Magnetic Force (MMF).

Just as an Electromagnetic Force (EMF) drives current around an electric circuit, so MMF drives magnetic flux through a magnetic circuit.

How to step up or step down the voltage for transformer?

Ok..to answer this question,firstly we must understand the formula for transformer.In an ideal transformer the formula is likes below :-

Vp /Vs = Np / Ns = Is / Ip

Vp = Voltage Primary Vs = Voltage Secondary

Np = Turn ratio Primary Ns = Turn ratio  Secondary

Ip = Ampere Primary Is = Ampere Secondary

1) For Step up transformer,The turn ratio for PRIMARY must greater than SECONDARY

2) For Step Down transformer,the turn ratio for SECONDARY must greater than PRIMARY

How to use a transformer formula?

From the formula,we can calculated the voltage,ampere and turn ratio in transformer.

EXAMPLE :

1) Calculate the value of secondary voltage if primary voltage = 240 VAC,primary turn ratio = 100 and secondary turn ratio = 50

Vp / Vs = Np / Ns

Vs = Vp x Np / Ns

Vs = 240 x 100 / 50

Vs = 120 VAC

2) Calculate the Ns ( secondary turn ratio ) if voltage primary = 11 kVAC, voltage secondary = 415 VAC and turn ratio for primary = 1800

Vp / Vs = Np / Ns

Ns = Np x Vs /Vp

Ns = 1800 x 415 / 11 k

Ns = 68 turn

Why  need EARTHING for transformer?

Earthing cable must be install at SECONDARY TERMINAL ( OUTPUT ).It important because for safety reason.The main objective is for avoid ” floating voltage ” when electric leakage happen.Then the RCCB can functioning properly to cut off the power supply.

That why the earthing system is very important in electrical wiring.I  call it the ” life protector cable” So..please ensure to connect the earthing cable for all electrical appliance or device..it can save our life.SAFETY FIRST