# What does V curves of synchronous motors indicate?

## What does V curves of synchronous motors indicate?

In power engineering & electrical engineering, V curve is the graph showing the relation of armature current as a function of field current in synchronous machines keeping the load constant.

What do you mean by V curve and inverted V curve of synchronous motor?

What is V Curve and inverted v curve? The graphical representation of armature current Ia vs field current If is called V-curve since the final view looks like English letter V. At the same time the power factor vs field current is called inverted V-curve of a synchronous motor.

What do you mean by V curves and Inveted V curves what information’s can be obtained from them?

As against this, if the power factor (cos ф ) is plotted against field current (If), then the shape of the graph looks like an inverted V. Such curves obtained by plotting p.f. against If, at various load conditions are called Inverted V-curves of synchronous motor. These curves are shown in the Fig: 2.27 (b).

### Why V curve shifts upwards as the load increases?

– Each V-curve is plotted for a particular load on shaft. – If load is increased, the plot shifts upwards, as the armature current increases, to supply more active power.

What is a generator V curve?

V-curve of Generator is basically a plot of variation of armature current with the change in field current. For a constant power, V-curve can only be obtained for generator connected to infinite bus / grid.

Why does the V curve shift upwards?

#### What is EMF equation of alternator?

V = 4.44 Kf KC KD f ΦT Volts. V = Actual generated Voltage per phase. KC = Coil Span Factor or Pitch Factor. KD = Distribution Factor. Kf = Form Factor.

What is synchronous motor?

A synchronous motor is one in which the rotor normally rotates at the same speed as the revolving field in the machine. The stator is similar to that of an induction machine consisting of a cylindrical iron frame with windings, usually three-phase, located in slots around the inner periphery.

What are the main characteristics of a synchronous motor?

Main Features of Synchronous Motors

• Synchronous motors are inherently not self starting.
• The speed of operation of is in synchronism with the supply frequency and hence for constant supply frequency they behave as constant speed motor irrespective of load condition.

## How the synchronous motor is used as a synchronous condenser?

A synchronous condenser is a conventional solution that has been used for decades for regulating reactive power before there were any power electronics compensation systems. A conventional synchronous condenser is an AC synchronous motor that is not attached to any driven equipment.

When synchronous motor works as a synchronous condenser it works as?

Working Principle of a Synchronous Condenser: A synchronous motor works on the principle of motional EMF that is, a conductor tends to rotate due to the effect of the magnetic field. To provide a magnetic field, two ways are used that is a three-phase AC supply and a constant DC power supply to the stator.

What is synchronous generator?

A synchronous generator is a synchronous machine which converts mechanical power into AC electric power through the process of electromagnetic induction. It is called synchronous generator because it must be driven at synchronous speed to produce AC power of the desired frequency.

### What are the V curves of a synchronous motor?

The V curves of a synchronous motor are shown below: The point at which the unity power factor occurs is at the point where the armature current is minimum. The curve connecting the lowest points of all the V curves for various power levels is called the Unity Power Factor Compounding Curve.

What is V-curve of armature current?

The graphical representation of armature current Ia vs field current If is called V-curve since the final view looks like English letter V. At the same time the power factor vs field current is called inverted V-curve of a synchronous motor. Just you connect, two three-phase wattmeters and an ammeter to the stator winding of the synchronous motor.

How to control the power factor of synchronous motor?

The power factor of the synchronous motor can be controlled by varying the field current I f. As we know that the armature current I a changes with the change in the field current I f. Let us assume that the motor is running at NO load.

#### What is the purpose of the inverted V curve?

V curves are useful for adjusting the field current. By controlling the field current, reactive power supplied to the motor can be controlled. A family of curves can be obtained by plotting the power factor versus field current at a constant load of synchronous motor. These curves are called Inverted V Curves.