What are the advantages of large air gap length in synchronous machines?

What are the advantages of large air gap length in synchronous machines?

Therefore longer air gap length improves the voltage regulation of synchronous machine. Synchronizing power is inversely proportional to the synchronous reactance Xs. Therefore with increase in air gap length, the synchronous reactance decreases and hence synchronizing power increases.

What is an air gap line in synchronous machine?

In the plot above, the air gap line (dotted blue) gives the relationship between mmf and flux density in the air gap. (Induced voltage is proportional to flux density). At higher field current levels, the iron in the machine saturates and the percentage of field mmf applied to the air gap is reduced.

Why the length of air gap in induction motor is kept minimum possible where as in a DC machine it is larger?

The smaller the air gap is, the lower that reluctance, and thus the higher the magnetic flux (which is the magnetic analog of current), allowing the motor to work more efficiently and at a higher power.

What happens if the air gap length is doubled?

What happens if the air gap length is doubled? If the air gap of an induction motor is doubled then the mmf and magnetizing current approximately doubles. Also increase in air gap length increases the overload capacity, offers better cooling, reduces noise and reduces unbalanced magnetic pull.

What are the disadvantages of closed slots?

The disadvantage of a closed slot stamping will be the delay in production as it may take upto couple of days to completly sew the coil on its core.

Why do we use open circuit test on 3 phase ALternator?

As the DC field excitation of an alternator is increased, its speed being held constant, the magnetic flux, and hence, the output voltage, will also increase in direct proportion to the current. …

When air gap is increase in induction motor?

If the air gap of an induction motor increases, 1) The permeability of the magnetic circuit rotor-to-stator will decrease. 2) The magnetizing inductance of the motor thus decreases. 3) The magnetizing current will increase; This will cause a poor power factor at all loads.

What is the relation between the power factor and air gap length?

What is the relation between the power factor and the air gap length? Explanation: If the air gap length is small, the dispersion coefficient decreases. As the dispersion coefficient decreases, the power factor increases.

Why is the air gap in a synchronous machine larger than in induction?

Synchronous machines have a separately excited field in the rotor, it is fed through other means and does not have to jump across the air gap, so the gap is bigger to facilitate manufacturing. According to me the stability of synchronous machine is indirectly related to air gap length. So to improve stability air gap is more for sync machines.

Why is the length of the air gap important?

Length of the air gap is a very important parameter as it greatly affects the performance of the machine. Length of the air gap is a very important parameter as it greatly affects the performance of the machine. Air gap in synchronous machine affects the value of SCR and hence it influences many other parameters.

Why is an air gap needed in a rotating machine?

Air gap in rotating electrical machine is a coupling medium to transfer electrical energy from stator to the rotor or vice versa. It is also required for free rotation and proper cooling of the machine.

Why is the air gap in an induction motor larger than in a transformer?

Therefore, the no-load current of an induction motor becomes 30 to 40 per cent of full-load current, which is remarkably larger than the no-load current of a transformer for a given kVA rating. The air gap in an induction motor should be made small so that the induction motor gives better performance.