Electrical Isolator in Substation-Types and Importance

1. Electrical Isolator in Substation: Types and Importance

2. An important component often overlooked in substations is ‘isolators’. An isolator in substations plays a significant role in ensuring the safety, efficiency, and reliability of the power system.  The complex and interconnected landscape of substations is where power generation, transmission, and distribution occur at a large scale. It isolates the electrical network from human contact to avoid accidents, regular system maintenance, and improve the system's overall stability. In this article, we will look deep into the world of isolators in substations, their types, and their importance in the system operation. What is an Isolator? An isolator (disconnector) is a form of mechanical switch used to isolate a particular section of an electrical circuit from the power source. This component ensures the circuit is completely de-energized as a safety precaution during maintenance hours. An isolator in substations is good at preventing accidents and providing a safe working environment.

3. The working principle of Isolator Isolators operate differently according to the need. It can work manually, semi-automatically, or fully automatically. Each serves a different cause. Isolators can be used as switches, allowing for the opening and closing of circuits based on specific needs.  However, in most cases, they are installed in a fixed position to maintain permanent isolation between components such as transformers or different sections of transmission lines. The primary function of an isolator is to isolate a specific circuit by preventing the electricity flow. This isolation is achieved by separating the circuit from the power source. Isolators are widely used in various electrical applications, including industrial equipment, household appliances, and power grids. Difference between electrical isolator and circuit breaker It is often observed that people mix up the concept of isolator and circuit breaker. However, both of them are designed to serve different requirements. Below are the differences between an isolator and a circuit breaker:

4. Device type based on loading condition • Isolator: Designed for off-load conditions, which means it's intended to be operated when the circuit is not carrying current. It's primarily used for maintenance and isolation purposes. • Circuit Breaker: It is designed to operate on-load conditions, which means it can interrupt the flow of current even when the circuit is carrying a load. It's primarily used to protect against faults and overloads in the power system. • Operation • Isolator: It requires human intervention to open or close the circuit. • Circuit Breaker: It is an automatic operation that senses faults or overloads and trips to isolate the affected circuit. • Device Action • Isolator: It is similar to a mechanical switch, which physically disconnects the circuit from the power source. • Circuit Breaker: An electronic device that uses semiconductor components like BJT or MOSFET to interrupt the current flow.

5. Safety • Isolator: It provides a safety measure by de-energizing the circuit before working on it. • Circuit Breaker: Protects the electrical system and equipment from getting damaged by quickly isolating faults. • Speed • Isolator: Isolator is typically slower in operation, as it requires manual intervention to operate. • Circuit Breaker: It is designed for quick operation to minimize the impact of faults on the system. • Additional Considerations • Isolators and circuit breakers are often used in pairs to create a safe and reliable electrical system. Isolators segregate specific sections for maintenance while circuit breakers provide ongoing protection. • The choice between an isolator and a circuit breaker depends on the requirements. For example, if frequent maintenance or isolation is needed, is more suitable. If rapid fault protection is critical, a circuit breaker would be preferred.

6. Types of electrical isolators • The isolators hold a crucial role in the smooth operation of a substation. These electrical isolators are primarily classified into three different categories. Here are the three types of isolators in substation.  • Double Break Type Isolators • Construction: It is made up of three post insulators with a flat male terminal in the center. • Operation: The central post insulator rotates, creating a horizontal space between the terminals. This is done through a lever mechanism. • Benefit: It ensures a clean and distinct separation of circuits. • Single Break Type Isolators • Construction: An arm contact is divided into male and female parts, connected to a post-insulator. • Operation: The movement of the post-insulator causes the arm contacts to move, opening or closing the circuit. • Benefit: It is very simple in design and makes it easier to operate.

7. Pantograph Type Isolators • Construction: It’s a compact design with a post-insulator and an operating insulator. • Operation: The pantograph structure allows for efficient movement and operation, especially in complex systems. • Benefit: It is a space-saving design, suitable for modern power systems. • Conclusion • From industrial uses to residential applications, isolators come in various types, each designed for specific applications, voltage levels, and system configurations. The choice of electrical isolators depends on the specific need. • You certainly need to reach out to an industry expert to know which isolator is suitable for your substation. You can contact KP Green Engineering Limited, a well-known manufacturer and supplier of isolators that offers a wide range of reliable and energy-efficient disconnectors (isolators) ranging from 12 kV to 420 kV.

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