The salient-pole construction for the field structure of an alternator is generally used for _______ machine.

• The salient-pole construction for the field structure of an alternator is generally used for 8 Pole machines.
• The salient-pole construction is a type of field structure used in alternators, which consists of a set of projecting poles on the rotor that interact with the stator windings to generate an electromagnetic field.
• While it is true that the salient-pole construction is commonly used in 8-pole alternators, it can also be used in machines with different numbers of poles.
• The choice of pole configuration depends on the specific application requirements, such as the desired output voltage and frequency, and the operating conditions of the machine.
• In general, the salient-pole construction is preferred for low-speed, high-power applications, as it provides better efficiency and stability than other types of field structures.

The a.c. the armature winding can be either star (Y) connected or delta (Δ) connected, depending on the specific design requirements and operating conditions of the alternator.

Star (Y) connection is commonly used in low voltage alternators where the line voltage is equal to the phase voltage. In this configuration, the ends of the three winding coils are connected together to form a common neutral point, which is then connected to the system neutral or ground. The line voltage is measured between the phase terminals and the system neutral, while the phase voltage is measured between any two phase terminals.

Delta (Δ) connection is typically used in high-voltage alternators where the line voltage is greater than the phase voltage. In this configuration, the winding coils are connected in a closed loop, with each coil connected to the next in a series. The line voltage is measured between any two phase terminals, while the phase voltage is equal to the line voltage divided by the square root of three.

The choice of winding connection depends on various factors, such as the required output voltage, the number of phases, and the operating conditions of the alternator.

• Drop-in alternator frequency is corrected by Increase Prime Mover Output.
• The frequency of an alternator is directly proportional to the speed of the rotor and inversely proportional to the number of poles in the machine.
• Therefore, any change in the speed of the rotor or the number of poles will result in a corresponding change in the output frequency of the alternator.
• When the frequency of an alternator drops below its rated value, it indicates that the rotor is turning slower than the synchronous speed, which can be caused by a variety of factors, such as increased load, mechanical losses, or a decrease in the prime mover output.
• To correct the drop-in alternator frequency, the prime mover output must be increased to compensate for the increased load or mechanical losses.
• This can be achieved by increasing the fuel supply to the engine, adjusting the governor setting, or increasing the input power to the prime mover.
• In some cases, it may be necessary to adjust the field excitation of the alternator to maintain a constant output voltage while increasing the prime mover output.
• This can be done by increasing the field current, which will increase the magnetic field strength and output voltage of the alternator.
• It is important to note that any changes to the prime mover output or field excitation must be carefully controlled to avoid overloading the alternator or causing other system issues.

• The pitch factor for a full pitch winding of a synchronous machine is 1.
• In a full-pitch winding, the coil span is equal to the pole pitch, which means that each coil spans one pole pitch and is wound around one pole before continuing to the next.
• This results in a sinusoidal distribution of emf along the stator periphery, which is similar to that of a single-phase alternator.
• Since the full-pitch winding has a uniform distribution of emf, the pitch factor is equal to 1.
• In other words, the actual emf induced in the winding is equal to the emf that would be induced if the winding were uniformly distributed over the stator periphery.

• In the case of Zero Power factor leading load on the alternator, the effect of armature reaction is to decrease the Induced EMF.
• When an alternator is operating under zero power factor leading load conditions, the current flowing through the armature winding leads the voltage across the winding.
• Under these conditions, the armature reaction of the alternator produces a demagnetizing effect on the main flux.
• This is because the armature reaction creates a flux that is perpendicular to the main flux and opposes its direction.
• As a result, the effective flux in the air gap is reduced, which leads to a decrease in the induced EMF.
• The demagnetizing effect of the armature reaction is more pronounced under leading power factor conditions because the armature current is in phase with the flux produced by the armature winding.

• In the synchronous motor rotor, copper losses are met by DC source.
• In a synchronous motor, the rotor is excited by a DC source, typically supplied by a separate DC excitation system.
• This DC source provides the necessary current to produce the magnetic field on the rotor and maintain synchronous operation.
• The copper losses in the rotor, which include both the resistance losses in the rotor winding and the eddy current losses in the rotor core, are typically small compared to the mechanical losses in the motor.
• Therefore, the DC source is primarily used to supply the field current to the rotor, rather than to directly compensate for the copper losses.
• However, in some cases, the copper losses in the rotor can become significant, particularly at high rotor currents or high speeds.
• Under these conditions, the DC source may need to supply additional current to compensate for the copper losses and maintain the required magnetic field strength.
• In general, the DC source for a synchronous motor is designed to supply enough current to maintain the required magnetic field strength and compensate for any copper losses that may occur.
• The specific design of the DC source depends on various factors, such as the size and rating of the motor, the operating conditions, and the type of DC excitation system used.

• In the case of the leading power factor, the terminal voltage of the alternator will Rise on removing the full load.
• In the case of a leading power factor, the current flowing through the load is leading the voltage waveform.
• This means that the current is reaching its peak before the voltage waveform reaches its peak.
• This results in a portion of the current waveform that is flowing in the opposite direction of the voltage waveform.
• When the load is removed, the current through the alternator becomes zero, and hence, the voltage waveform is no longer distorted by the leading current.
• As a result, the voltage waveform will rise slightly when the full load is removed.
• However, the amount of voltage rise depends on the design of the alternator and the characteristics of the load.

• When any one-phase of a 3-phase synchronous motor is short-circuited, the motor will refuse to start.
• If the short circuit is severe enough to cause a significant imbalance in the magnetic field, the motor may not start at all.
• In this case, the motor will draw excessive current and overheat, which may damage the motor winding insulation or other components of the motor.
• However, if the short-circuit is not severe, the motor may still start but with reduced performance.
• The motor will run at a reduced speed and torque because the shorted phase will not contribute to the magnetic field, resulting in an unbalanced field.
• If the short-circuit is not severe, the motor may still start but with reduced performance.
• The motor will run at a reduced speed and torque because the shorted phase will not contribute to the magnetic field, resulting in an unbalanced field.
• In either case, it is essential to address the short circuit promptly to prevent further damage to the motor.

The angular displacement between two interconnected stations is mainly due to the difference in rotor angles of the interconnected generators, which is caused by differences in mechanical torque inputs to the generators, such as changes in load.

The armature reactance of both alternators and the reactance of the interconnector can affect the magnitude of the torque developed between the interconnected generators, and hence, the rate at which the generators adjust their rotor angles to maintain synchronism.

The synchronous reactance of the alternators also affects the magnitude of the torque developed between the generators.

So, the correct answer is "All of the above" as all these factors can affect the magnitude of the torque and, consequently, the rate at which the generators adjust their rotor angles to maintain synchronism.