What Determines When A Synchronous Motor Is At Normal Excitation

October 11, 2024 Post a Comment

What determines when a synchronous motor is at normal excitation

Case 2 − Normal Excitation of Synchronous Motor If (Ef=V), the synchronous motor is said to be normally excited. Under this condition, the reactive power of the motor is zero (i.e., Q = 0), that is the motor is neither absorbing nor delivering reactive power. Thus, the power factor of the motor is unity.

How can a synchronous motor be made to produce a leading power factor?

A Synchronous Motor can be made to operate at unity and leading power factor by just increasing its excitation voltage i.e. by increasing the field current. This advantage of Synchronous Motor is used to improve the power factor.

What two factors determine the synchronous speed of a motor?

The synchronous speed of an AC motor is determined by the frequency of the source and the number of poles. The RPM is calculated by multiplying the frequency times 60 and dividing by the number of pairs of poles.

What will happen if the field of synchronous motor is under Excited?

The synchronous motor operates at a lagging power factor when the excitation is under excited. The motor operates at a unity power factor at normal excitation.

Does the excitation affect the power factor?

A change in the excitation of an alternator running in parallel with other affects only its KVA output; it does not affect the KW output. A change in the excitation, thus, affects only the power factor of its output.

What is excitation voltage in synchronous motor?

The excitation voltage of synchronous motor refers to the DC supply given to the rotor to produce the required magnetic flux. The excitation voltage (Ef) of a synchronous motor can be determined for different power factors using complex algebra.

How can you increase the power output of a synchronous motor?

Changing the energy flow-rate into the prime mover driving the generator is the ONLY way to change the output of the generator--because the generator is an electric machine for converting torque into amperes.

How can you change the power factor of a synchronous motor?

The fact that the field poles of a synchronous motor are magnetically in line with the stator flux allows dc current on the field to replace ac magnetizing current on the stator. Since power factor is determined by the magnetizing current, the power factor is adjustable by changing the field current.

Can a synchronous motor operate at any power factor?

A synchronous motor is capable of operating at all types of power factor i.e. either UPF, leading, or lagging power factor.

At which factors synchronous speed depends?

The speed of a synchronous motor is dependent on the frequency of the power source and the number of poles the stator has. RPM increases directly with frequency and inversely as the number of poles.

Does voltage affect synchronous speed?

With lower voltage, the power factor is likely to be better and hence the field current will be reduced by AVR. Synchronous motor cannot run at any other speed other than synchronous one. Hence, if the motor continues to run, it will be at rated / synchronous speed, i.e. there is no change in speed.

What will be the stability of a synchronous motor with increase in excitation?

Right Answer is: B By increasing its excitation, the stability of the machine will increase.

What is the effect of increasing the load of a synchronous motor running with normal excitation?

Detailed Solution. When a synchronous motor is operating with normal excitation, with the increase in load: The motor continues to run at a synchronous speed as it is a constant speed motor. The torque angle δ increases.

How is the field excitation of a synchronous motor increased?

For a constant field excitation, when the load on the synchronous motor increases the current drawn by the motor increases. But by keeping the load constant we can operate a synchronous motor at different power factors by varying the field excitation.

How do you excite a synchronous motor?

To excite the field winding of the rotor of the synchronous machine, direct current is required. Direct current is supplied to the rotor field of the small machine by a DC generator called Exciter. A small DC generator called Pilot Generator supplies the current to the Exciter.

What happens if you increase excitation power?

If we increase excitation that increase excitation current so magnetic flux increase and stator voltage increase. Increased stator voltage increase magnetic flux of all inductive load like motot etc.. connected with generator,so reactive power increase and power factor decrease.

How do you control excitation voltage?

This excitation voltage is then controlled by varying field current of main exciter through a pilot exciter. An automatic voltage regulator is then used to control both pilot and main excitation voltage according to the demand at the output terminal.

What happens if excitation is changed?

If the excitation or field current is changed, the armature current changes, and back emf also will be changed accordingly and hence power will remain constant. Field current or excitation is directly proportional to the torque, therefore torque will be change.

What are the requirements of excitation system?

The requirements of an excitation system include reliability under all conditions of service, a simplicity of control, ease of maintenance, stability and fast transient response. There are three main types for standard brushless self excited machines. Shunt or self excited, Auxiliary wound and Permanent Magnet (PMG) .

What is the principle of excitation?

excitation, in physics, the addition of a discrete amount of energy (called excitation energy) to a system—such as an atomic nucleus, an atom, or a molecule—that results in its alteration, ordinarily from the condition of lowest energy (ground state) to one of higher energy (excited state).