What are Electrical Isolators? Circuit Breaker vs Isolator I Electronicsinfos

What are Electrical Isolators? 

What are Electrical Isolators Circuit Breaker vs Isolator I Electronicsinfos

Electrical isolators, also known as electrical disconnect switches or isolation switches, are devices used to provide electrical separation between a circuit or equipment and its power source. 

The main function of electrical isolators is to interrupt the flow of current in a circuit and create an air gap between the power source and the equipment. This gap ensures that no electrical energy is transferred to the equipment, making it safe for personnel to work on or around it.

Isolators are usually installed in series with other protective devices such as circuit breakers or fuses to provide a complete isolation and protection system. When an electrical isolator is opened or switched off, it breaks the electrical circuit and physically separates the conductors, preventing the flow of current.

Types Of Isolators

There are several types of isolators used in electrical systems. The specific type of isolator selected depends on factors such as the voltage level, current capacity, and application requirements. Here are some common types of isolators:
  • Verticle Break Type isolators
  • Knife-Blade Isolators
  • Pantograph Isolators
  • Centre-Break Isolators: 
  • Double-Break Isolators
  • Semi-pantograph Isolators

Vertical-Break Isolators

Vertical-break isolators are primarily used in extra-high voltage transmission systems. They feature vertically oriented blades that move up and down to establish or interrupt the circuit. Vertical-break isolators are designed to handle high currents and provide reliable operation in demanding environments.

Knife-Blade Isolators

These are the most basic and commonly used isolators. They consist of a pivoting knife blade that can be manually opened or closed to establish or interrupt the electrical circuit. Knife-blade isolators are typically used for low-voltage applications.

Pantograph Isolators

Pantograph isolators, also known as gang-operated switches, are designed for medium to high-voltage applications. They consist of multiple blades that move in a scissor-like motion to establish or break the electrical connection. Pantograph isolators are often used in substations and transmission lines.

Centre-Break Isolators

Centre-break isolators are commonly used in medium to high-voltage systems. They have a central rotating post with two sets of contacts on either side. When opened, the contacts move away from each other, creating a visible air gap. Centre-break isolators are typically motorized for remote operation.

Double-Break Isolators

Double-break isolators are similar to centre-break isolators but have two rotating posts with sets of contacts, providing an additional breaking point. These isolators offer improved performance in terms of current interruption and are often used in high-voltage applications.

Semi-pantograph Isolators

Semi-pantograph isolators combine the characteristics of knife-blade isolators and pantograph isolators. They are commonly used in medium voltage applications and provide a compact and reliable solution for isolation.

Circuit Breaker vs Isolator

Circuit breakers and isolators are both important components of electrical systems, but they serve different functions. Here's a comparison between circuit breakers and isolators

Circuit Breaker


A circuit breaker is designed to protect electrical circuits from overloads, short circuits, and faults. It automatically detects abnormal current conditions and interrupts the circuit to prevent damage to the equipment and minimize the risk of electrical hazards.


Circuit breakers have built-in mechanisms that can trip or open the circuit in response to excessive current or faults. They can be either thermal, magnetic, or a combination of both, and they are often designed to be resettable after tripping.

Current Interruption

Circuit breakers are capable of interrupting and breaking the flow of current in a circuit. They are specifically designed to handle the task of interrupting high fault currents and protecting the circuit against excessive current levels.


Circuit breakers provide both overload protection and short circuit protection. They can trip in response to excessive current or a fault and quickly disconnect the circuit to prevent damage to the equipment and wiring.

Isolator (Disconnect Switch)


An isolator, also known as a disconnect switch or isolating switch, is primarily used for electrical isolation and physical disconnection of a circuit or equipment from the power source. Its main purpose is to ensure that a circuit or equipment can be safely de-energized and isolated for maintenance or repair work.


Isolators are manually operated switches that are opened or closed to establish or break the electrical connection. They provide a visible break in the circuit, physically separating the conductors and creating an air gap.

Current Interruption

Isolators are not designed for interrupting high fault currents like circuit breakers. Their main function is to isolate the circuit or equipment from the power source, rather than interrupting the flow of current during abnormal conditions.


Isolators are primarily used for safety purposes, providing a reliable means of electrical isolation for personnel working on or around the equipment. They allow maintenance or repair work to be carried out without the risk of electric shock or accidental energization.

In summary, circuit breakers are protective devices that monitor and interrupt the flow of current during overloads or faults, while isolators are switches used for the physical isolation and disconnection of circuits or equipment. Both components have distinct roles in ensuring the safety and proper operation of electrical systems.

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