What is an ideal transformer?

An ideal transformer is a hypothetical transformer that has the following properties:

Resistance of Primary Coil is zero
Resistance of Secondary Coil is zero.
The Core has infinite permeability.
Due to infinite permeability, there is no need for MMF to stablish flux in the core.
It has zero leakage flux and leakage inductance. Due to this, all the flux of the primary side is linked with the secondary side.
There is no energy loss due to resistance, hysteresis, and eddy current.
The efficiency of an Ideal transformer is 100 percent.

An ideal transformer does not exist in practical life. All real-life transformers have efficiency below 100 percent. But in electrical engineering, we assume every transformer is an ideal transformer to solve the numerical problem.

A Circuit Diagram of an iron core ideal transformer has been shown below. it consists of two coils wound in the same direction on a common magnetic core. The Winding which is connected to the Supply is known as the primary winding. Winding that is connected to the load is known as Secondary winding.

Due to zero impedance of primary and secondary winding, Emf induced in the primary winding is equal to the primary supply voltage and also secondary induced Voltage is also equal to secondary terminal voltage.

When the Primary side of the transformer is connected to the supply(V_p), a current(I_p) will start to flow and set up a magnetic flux (𝚽). When this magnetic flux will link with the primary and the secondary side of the winding, an EMF will induce the secondary winding (E₂) and primary winding(E₁).

When the Secondary winding of the transformer is connected to a load, a secondary load current(I_s) starts flowing in the secondary winding of the transformer.MMF(N_pI_p) set up by the primary side is now balanced by MMF(N_sI_s) set up by the secondary current.

Transformer Equation

From the above discussion, we have found that the Primary side MMF is equal to the Secondary side mmf hence it can be written as

(Primary Side MMF) = (Secondary Side MMF)

At any Instant Power given to primary winding will be equal to Power Consumed by the load connected to the secondary winding. Hence it can be written as

(Primary Side Power) = (Secondary Side Power)

For an ideal transformer, Primary Voltage is equal to primary induce voltage and Secondary voltage is equal to secondary Induce voltage.

Ideal Transformer phasor diagram on Load

In the Primary side of the transformer, By Lenz's law Induce voltage(E_p) is equal and opposite to supply Voltage(V_p). Since Primary winding induces Voltage (E_p) and Secondary Side Induces voltage (E_s) is induced by common magnetic flux(𝚽)hence these two voltages have the same direction but are opposite to primary supply Voltage(V_p).In every physical quantity of primary and secondary sides, magnetic flux(𝚽) is common. hence it will be taken as a reference while drawing a phasor diagram.