Introduction:
A synchronous motor is an AC motor that operates at a constant speed determined by the frequency of the power supply. It is often used in applications where precise speed control is required, such as in industrial processes or power generation. One of the unique features of a synchronous motor is its ability to operate at a leading power factor.

Explanation:
A synchronous motor working at a leading power factor can be used as a phase advancer. This means that it can be used to improve the power factor of an electrical system.

What is a power factor?
Power factor is a measure of how effectively electrical power is being used in a system. It is the ratio of real power (in watts) to apparent power (in volt-amperes). A power factor of 1 indicates that all the power being supplied is being used effectively, while a power factor less than 1 indicates that there is reactive power in the system.

Leading power factor:
A leading power factor occurs when the current leads the voltage in an AC circuit. This can happen when the load in the circuit is capacitive in nature. In a capacitive load, the current waveform leads the voltage waveform. When a synchronous motor operates at a leading power factor, it means that it is acting as a capacitive load in the system.

Phase advancer:
A phase advancer is a device that is used to improve the power factor of an electrical system. It introduces a leading power factor to compensate for the lagging power factor caused by inductive loads. In this case, a synchronous motor working at a leading power factor can act as a phase advancer.

Advantages of using a synchronous motor as a phase advancer:
- Improved power factor: By introducing a leading power factor, the synchronous motor helps to correct the lagging power factor caused by inductive loads in the system. This improves the overall power factor of the system, leading to more efficient power utilization.
- Reduced reactive power: The reactive power in the system is reduced, leading to a decrease in the current flowing through the system. This helps to reduce the losses in the system and improve the overall efficiency.
- Voltage regulation: A synchronous motor operating at a leading power factor can also help to regulate the voltage in the system. It can act as a voltage booster, compensating for voltage drops caused by inductive loads.

Conclusion:
In conclusion, a synchronous motor working at a leading power factor can be used as a phase advancer to improve the power factor of an electrical system. It helps to compensate for the lagging power factor caused by inductive loads and improves the overall efficiency of the system. Additionally, it can also act as a voltage booster and provide voltage regulation in the system.