Short-Question

# How do you calculate no load current of a 3 phase induction motor?

## How do you calculate no load current of a 3 phase induction motor?

It means the three-phase motor will be connected in star connection (one end short and another end supply). The motor will take 10% of the full load current. therefore, No load current at star connection = 0.1 x Motor Full load current.

## Why is the power factor of a 3 phase induction motor low at no load?

When the motor is operated on no load, the motor draws very less load current. The load current is drawn to meet the torque requirement to drive its rotor. At no load, the rotor current is I2. The phase angle between the I2 and rotor induced voltage E2 is more hence the power factor of the rotor circuit is low.

What does the power measured in the no load test of an induction machine represent?

When applied voltage is zero the core losses and stator copper losses are zero. Therefore, power input at no load and zero voltage applied represents the windage and friction losses.

How do you calculate no load?

The calculation of no-load (Iron) losses is based on the ratio of the voltages being measured and the rated voltage squared and the results multiplied by the no-load value from the data sheet.

### Why is the power factor low under no load conditions?

At low load or no load condition because of presence of only magnetizing current in the stator windings, causes low power factor operation of the power system, since magnetizing current is highly inductive in nature.

### What is the no load power factor?

With no-load, a small amount of current is drawn from the primary side to set up the required magnetic flux in the magnetic core. This is known as the “no-load current.” The no-load current is approximately 3-5% of the full load current and accounts for the losses in the transformer.

Why no load current of induction motor is high?

Magnetic circuit of Induction motor has large reluctance than transformer due to air gap between stator and rotor, more mmf(magneto motive force is equal to product of current and number of turns) or more current is required to set up working flux in Induction motor, this is the reason of high no load current in …

What is no load current of induction motor?

The current drawn by the induction motor when it is not coupled to the driven equipment is called no-load current of the motor. The equivalent circuit of an induction motor at no load is as given below. The no-load current produces the magnetic field in the motor. There are two parts of no-load current.

## How does no load test on induction motor work?

The connection diagram for no load test on three phase induction motor is shown above. The wattmeter, ammeter and voltmeter, readings are taken. The total power input is given by the two wattmeters W 1 and W 2. At no load, the input power is supplied to meet out the losses.

## Why does the watt meter show a negative reading during the no load?

I’m considering that the question intends to understand about why a watt-meter (one of two) shows a negative reading with induction motor on no-load using two-watt-meter method. The reason why a watt-meter displays an negative reading is due to highly inductive nature of induction motor at low-loads/no-load (similar to transformer).

How is three phase power measured in two wattmeter?

The three methods are: In this post, we will discuss the Two Wattmeter Method for power measurement. Two Wattmeter Method: In two wattmeter method, a three phase balanced voltage is to a balanced three phase load where the current in each phase is assumed lagging by an angle of Ø behind the corresponding phase voltage.

What is the formula for no load test?

P constant = P i = P 1 + P 2 = Sum of the two wattmeter readings. Figure: Circuit diagram for no-load test on a 3-phase induction motor.