Consider the principle that the torque in a rotating machine is proportional to peak of stator MMF(Fs), rotor MMF(Fr) and the angle between them(δ). Following statements relate to Fs,Fr and δ in different machine. Which of these statements are correct?(i) δ is fixed in DC machine(ii) Fs is fixed in DC shunt machine(iii) δ is variable in induction machine(iv) Fr is fixed in synchronous machne(v) Fr is variable in DC machine(vi) Fr is fixed in induction motor(vii) resultant of Fs and Fr is fixed in synchronous motor

Synchronous Machines topics include: Physical concepts, Emf Polygons, power angle and power factor control of synchronous machines, excitation systems for synchronous machines, flux and mmf phasors in synchronous machines,synchronous machine applications and measurement of xd and xq. A synchronous machine is an electrical machine that operates at synchronous speed. It is an AC machine that uses a rotating magnetic field to generate power.  Here are some characteristics of synchronous machines: Rotation speed: The rotor of a synchronous machine rotates at the same speed as the rotating... Show more

Synchronous Machines topics include: Physical concepts, Emf Polygons, power angle and power factor control of synchronous machines, excitation systems for synchronous machines, flux and mmf phasors in synchronous machines,synchronous machine applications and measurement of xd and xq.

A synchronous machine is an electrical machine that operates at synchronous speed. It is an AC machine that uses a rotating magnetic field to generate power. 

Here are some characteristics of synchronous machines:
Rotation speed: The rotor of a synchronous machine rotates at the same speed as the rotating field.
Magnetic field: The rotor side of a synchronous machine has a fixed magnetic field.
Power supply: Synchronous machines require an AC supply to work.

Power system applications: Synchronous machines are used in many power system applications, including:
Power generators
Power factor correction
Driving constant speed mechanical loads

Household appliances: Synchronous machines are used in small household appliances such as air coolers, refrigeration, fans, and air conditioners. 

Synchronous machines have several advantages and disadvantages:

Advantages
Synchronous motors have several advantages and disadvantages.
Synchronous motors can operate under any power factor, lagging as well as leading.
Synchronous motors are not self-starting and cannot be started on load.

Disadvantages
Synchronous motors have a higher cost per kW output than induction motors.
Synchronous motors require collector rings and brushes, which increases maintenance.
Synchronous motors cannot be used for variable speed applications or applications requiring frequent starting. 

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