Last Updated on October 29, 2023 by Electricalvolt

Air gap power in an induction motor is the output power of the stator or input power to the rotor. The electrical power fed to the stator converts into the magnetic power that travels through the air gap of the motor, which is called the air gap power of the induction motor.

The motor converts electrical energy into mechanical rotational energy. The input voltage is fed to the stator of an induction motor. The stator coil opposes the applied voltage, and this opposition limits the starting current of the motor. The flux is generated in the stator, which travels through the air gap and gets linked to the rotor conductors. The air gap power is equal to the rotor input power.

The following formula expresses the input power drawn by the induction motor.

**P=√3* VL*IL* cosΦ ———-(1)**

Where,

VL-Line voltage

IL- Line current

cosΦ- Power Factor

The electric power drawn is converted into the magnetic power. The air gap between the stator and the rotor is unwanted but necessary for motor operation. Without having an air gap, the rotation of the rotor is not possible. However, the losses in the motor can be minimized by keeping the air gap length as minimum as practically possible. The following losses occur in the motor at no load.

**Core Losses or No Load Losses**

The loss comprises the eddy current and hysteresis loss. The loss is more or less constant, called the fixed losses.

**Stator**** I ^{2}R loss :**

The loss occurs due to heat loss in the resistance of the stator because of the current flowing through the stator coils.

Thus, the total losses in the stator at no load are given by;

**PstL=Ps(h+e)+Ps ————–(2)**

Where,

PstL – Total losses in the stator at no load

Ps(h+e)- Core losses-Eddy current and hysteresis loss

Ps- Copper loss in the stator

**The air gap power(Pg) can be calculated as;**

=Total Input power – Losses in the stator

**Pg=√3VL x IL cosΦ-[(Ps(h+e)+Ps)] ——(3)**

The air gap power (Pg) is transferred to the input to the rotor.

**The air gap Power= Rotor Input Power**

The air gap power gets converted into kinetic rotational power. **The following losses occur in the rotor.**

1. Rotor copper loss

2. Rotor core loss- Negligible

3. Friction, windage, and stray losses

**The air gap power(P _{g)} can also be calculated by following the formula.**

**P _{g }= The mechanical power output(**

**Pm**

**) + Rotor Ohmic loss + Friction and Windage loss**

**Calculation of Air Gap Power**

The equivalent rotor circuit of an induction motor is shown below.

The X_{2} and E_{2} are the rotor reactance per phase and EMF /Phase induced in the rotor circuit. R2/s is the rotor winding resistance.

**The rotor input power = Air Gap Power**

**The rotor copper loss = sPg****Mechanical power output(Pm)= (1-s)Pg**

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