Understanding the Purpose and Applications of Reactors in Electrical Systems

Reactors, also referred to as inductors, are essential components in electrical and power systems. Their primary function is to manage current, voltage, and reactive power in various applications by utilizing their inductive properties. Below is a detailed explanation of their purpose, classification, and applications.

I. What is a Reactor?

A reactor is essentially a coil of wire designed to create inductance. When current flows through a conductor, it generates a magnetic field. In reactors, this magnetic field is intensified by increasing the inductance through specific structural designs:

1. Hollow Reactors:
   • Wound in a solenoid shape without an iron core.
2. Iron Core Reactors:
   • Insert an iron core into the solenoid to enhance inductance and magnetic field strength.

II. Types of Reactance

Reactance refers to the opposition to the flow of alternating current due to inductance or capacitance. Reactors are associated with inductive reactance, while capacitors are linked to capacitive reactance.

III. Classification of Reactors

Reactors can be categorized based on their structure, connection method, function, and purpose:

1. By Structure and Cooling Medium:

• Hollow Type: Simple solenoid without a core.
• Iron Core Type: Includes an iron core for increased inductance.
• Dry Type: Uses air for cooling.
• Oil-Immersed Type: Uses oil for cooling and insulation.

2. By Connection Method:

• Parallel Reactors: Connected in parallel with the load or power lines.
• Series Reactors: Connected in series to the circuit.

3. By Function:

• Current Limiting: Restricts the flow of fault or inrush current.
• Compensation: Balances reactive power to stabilize the system.

4. By Usage:

• Current Limiting Reactor: Limits short-circuit current to protect equipment.
• Filtering Reactor: Filters harmonic currents in power systems.
• Smoothing Reactor: Reduces ripple currents in DC circuits.
• Power Factor Compensation Reactor: Improves power factor by balancing reactive power.
• Arc Suppression Coil: Extinguishes arcs in grounding systems.
• Series and Parallel Resonant Reactors: Used in tuned circuits for resonance purposes.

IV. Applications of Parallel Reactors

Parallel reactors play a vital role in improving reactive power management and operating conditions in power systems. Key applications include:

1. Reducing Transient Overvoltage:

   • In lightly loaded or unloaded power lines, reactors counteract the capacitance effect to reduce transient overvoltages at power frequency.

2. Improving Voltage Distribution:

   • In long-distance transmission lines, parallel reactors stabilize voltage distribution along the line.

3. Balancing Reactive Power:

   • Reactors help prevent excessive reactive power flow and reduce power losses in the system.

4. Simplifying Generator Synchronization:

   • By reducing steady-state power frequency voltage on high-voltage buses, reactors make it easier to synchronize generators with the system.

5. Preventing Self-Excitation Resonance:

   • Reactors prevent self-excitation resonance in generators connected to long transmission lines.

6. Neutral Point Grounding:

   • Small reactors can compensate for line-to-line and line-to-ground capacitance, accelerating the automatic extinguishing of residual currents.

7. Current Limiting and Filtering:

   • Reactors limit excessive current during faults and filter harmonic currents to ensure smooth system operation.

V. Summary of Reactor Functions

Reactors are indispensable in modern power systems for:

• Current and voltage management.
• Reactive power balancing.
• Harmonic filtering and power quality improvement.
• Protecting equipment from transient or fault conditions.

By understanding the structure, classification, and applications of reactors, engineers and procurement professionals can make informed decisions in selecting the appropriate reactor for specific applications. This knowledge helps optimize system performance, improve reliability, and ensure compliance with electrical standards.