Short Answer:

Reactive power is the part of electrical power that does not perform any useful work but is essential for maintaining voltage levels in AC power systems. It helps in creating and sustaining electric and magnetic fields in inductive and capacitive devices like motors, transformers, and capacitors.

The significance of reactive power lies in its role in ensuring the proper operation of electrical equipment, voltage control, and overall system stability. Without reactive power, AC systems would experience voltage drops, leading to poor performance or even failure of connected devices.

Detailed Explanation:

Significance of Reactive Power

In an AC electrical system, total power supplied is made up of two parts: real power (P) and reactive power (Q). Real power performs actual work like lighting a bulb or turning a motor. Reactive power, on the other hand, flows back and forth between source and load and is used to build up and collapse magnetic and electric fields in devices.

Reactive power is measured in volt-ampere reactive (VAR) and is essential for the functioning of devices like:

• Inductive loads (e.g., motors, transformers), which need magnetic fields to operate.
• Capacitive devices, which store energy in electric fields.

Though reactive power does not contribute to mechanical work or heat production, it is a vital support element in any AC network.

Key Roles of Reactive Power

1. Voltage Regulation:
   Reactive power helps maintain voltage levels in power systems. Low reactive power causes voltage drops, while excessive reactive power causes voltage rise. Balanced reactive power ensures all devices work within safe voltage ranges.
2. Stable Operation of Inductive Devices:
   Devices like motors and transformers rely on magnetic fields to function. These fields are created and maintained using reactive power. Without it, the equipment will not start or run efficiently.
3. Transmission Support:
   Reactive power supports long-distance power transmission by controlling voltage along the line. It helps in preventing blackouts and equipment damage due to over or under-voltage conditions.
4. Power Factor Control:
   Reactive power affects the power factor of a system. High reactive power lowers the power factor, making systems less efficient. Managing reactive power with capacitors or synchronous condensers helps improve power factor and reduce energy loss.
5. System Stability and Protection:
   Proper reactive power management enhances the reliability of the electrical grid. It supports system stability during disturbances like sudden load changes or faults.

Sources of Reactive Power

Reactive power can be both absorbed and generated by various components:

• Absorbed: By inductive loads like motors, coils, and transformers.
• Generated: By capacitors, synchronous condensers, and generators with excitation systems.

Reactive power compensation is the method used to balance reactive power in the system. Capacitor banks are commonly installed in industries to supply leading reactive power and neutralize lagging power from motors.

Impact of Poor Reactive Power Management

• Increased energy losses in transmission.
• Overloaded generators and transformers.
• Poor voltage regulation leading to malfunction of sensitive equipment.
• Higher electricity bills due to poor power factor.

Proper management involves continuous monitoring and the use of automation like automatic power factor correction (APFC) panels.

Conclusion:

Reactive power is crucial for the safe and efficient operation of AC electrical systems. It doesn’t do direct work but supports the functioning of inductive and capacitive devices by maintaining voltage and power balance. Its significance lies in voltage control, system stability, equipment operation, and power factor management. Without reactive power, the entire power system would be unreliable and inefficient.