The Differences Between Isolators and Circuit Breakers

Electricity is a powerful source of energy, allowing for countless systems, appliances, and devices to function with power. As electricity is volatile in its nature, it is important that various devices are used to mitigate its flow and protect systems from surges, faults, and other issues. Circuit breaker and isolator devices are two common types of equipment that are often used for dealing with electrical faults. As each device presents its own unique functionality, construction, and application, understanding the differences between the two can be very beneficial when searching for protection devices.

Circuit breakers are a form of automatically operated switch, and they are specifically designed to serve as a protection device for an electrical circuit. While there are many circuit breakers types that accommodate a wide range of applications, all share similar characteristics for their operation. Generally, the circuit breaker will first detect a fault condition in the circuit, and this can be achieved through a number of methods or parts. Once the fault is detected, however, the contacts of the device are forcibly opened, breaking the flow of current. As arcs tend to be produced from the separation of contacts, various systems may be put in place to quench any resulting arcs.

The operation of circuit breakers is often automatic, though the device will remain tripped until the fault condition is cleared and the contacts are closed again through manual means. If a circuit breaker trips as soon as the device is reset, the fault may still be present and appliances, connections, and other sections of the electrical circuit should be checked. As circuit breaker devices greatly vary in their configuration and ratings, they may be used for applications ranging from 125 A to around 72.5 kV depending on their type.

Electrical isolators, also known as disconnectors, are another switch type that is implemented within circuits or devices in order to isolate parts of power circuits or instruments. Through either physical or electrical means, the isolator removes the circuit or equipment piece from the supply of power. As isolators are a type of offload device, they cannot be operated while current is flowing through them. Instead, they must be manually operated during offload conditions, and they do not have any arc suppression capabilities like the circuit breaker. With their method of operation, an isolator is most often used during maintenance procedures to provide safety to workers. Depending on the application in question, primary electrical isolator types include the double break, single break, and pantograph type isolator.

With the various differences between circuit breakers and isolators, both devices serve their own applications while providing a somewhat similar use. With the circuit breaker, electronics and appliances can be well protected from faults while current is flowing during standard operations. With isolators, power is only impeded during maintenance or repair work. While isolators are only used during offload instances, the functionality of circuit breakers continues in both offload and on-load conditions. Lastly, the breaking capacity of isolators is much lower, while circuit breakers can have high values. Despite the circuit breaker seeming more powerful in its characteristics, its role for live circuit protection demands such abilities while the isolator is meant for repair or maintenance only.


April 29, 2022
December 6, 2021

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