Electrical Isolator: Types, Working and Applications (Guide)

In order to maintain the circuit, an isolator acts as a switching device that ensures that the circuit is not completely triggered. The circuits are also isolated by these switches. Industrial, distribution of electricity, etc., are some of the applications for these switches. For isolating equipment such as transformers and circuit breakers, high voltage isolation switches are used in substations. Circuit isolation is usually the purpose of disconnector switches rather than circuit control. Activation of isolators can be automatic or manual. Electrical isolators are discussed in this article along with their types and applications.

What is an Electrical Isolator?

As an electrical isolator or isolation switch, an electrical isolator controls the de-energization of a portion of an electrical circuit for maintenance or service. It prevents current from flowing through a circuit while it is being worked on by disconnecting it from the main power source. Maintenance personnel and equipment need to be protected from injury. A comprehensive safety mechanism for electrical systems can be provided by electrical isolators in conjunction with circuit breakers and other protective devices.

Isolators are commonly used in power distribution and transmission networks, as well as in industrial and high-voltage applications. Designed to handle high voltages and currents, they can be operated manually or automatically. During the open position, the isolator creates a visible gap between the contacts, which ensures that the circuit is unenergized. In addition to providing a reliable visual confirmation that maintenance activities can proceed safely, this visible gap is an important feature. The electrical isolators play an important role in preventing accidental energization of circuits and ensuring electrical safety in maintenance operations.

Working Principle

It is the safe disconnection and isolation of electrical circuits that is the principle behind electrical isolators. The devices prevent electrical shocks and short circuits from occurring while parts of an electrical system are being maintained. Physically breaking the electrical circuit is the main principle involved in preventing current flow.

By separating the electrical contacts, an isolator closes the circuit and stops electricity from flowing. For complete disconnection, there must be at least a small physical gap between the contacts. There is usually a visible and clear indication of whether the isolator is open or closed, such as a lever or switch. Having visual confirmation of the circuit's de-energization is essential for maintenance personnel.

Generally, electrical isolators need to be operated as follows:

• Opening Operation: A handle or lever is moved to the open position to open the isolator. During this process, the contacts are mechanically separated, resulting in a physical gap that disconnects the circuit from its power source.

• Closing Operation: By moving the handle or lever in the closed position, the operator closes the isolator. When the contacts are brought together again, current begins to flow through the circuit.

A motorized mechanism or a control system may operate the isolator in automated systems. Physical separation between the electrical contacts is critical to the operation of the isolator, which guarantees that there is no current flowing through the disconnected part of the circuit. Keeping the equipment and personnel separated is important for safety during maintenance operations. Learn more on Bliaki.

Types

Each type of electrical isolator has been designed for a specific application or operating environment. A brief description of each type of electrical isolator follows:

Single Break Isolator: A single break isolator consists of one breakpoint per phase and is the simplest type of isolator. Most of them are used in applications requiring low to medium voltages. In order to interrupt the circuit, the contacts of the isolator separate. In most cases, the operator opens or closes the contacts manually by moving a handle or lever. Disconnection is visually and reliably assured by physically separating the contacts. In industrial automation systems and distribution networks, these isolators are commonly used in isolation applications.

Double Break Isolator: They provide a higher level of isolation and are suitable for applications requiring higher voltages due to their two break points per phase. Dual-contact isolators create a larger isolation gap when their contacts open simultaneously. In addition to providing more effective isolation, this double break mechanism increases the distance between the contacts, increasing safety. High voltage transmission lines, substations, and other applications require double break isolators for enhanced isolation.

Pantograph Isolator: It is named as such due to its distinctive scissor-like operating mechanism, reminiscent of a pantograph, which is used in high voltage applications. When the isolator is opened, the pantograph mechanism provides a large clearance distance, enabling compact design. The design can be used in high voltage substations and other installations. In many cases, pantograph isolators are motorized, which allows them to be operated remotely and automatically. Substations and transmission lines with extra high voltage (EHV) need reliable isolation due to space constraints.

Vertical Break Isolator: An isolation point is clearly visible and clearly visible with vertical break isolators. High voltage applications commonly use these isolators. An isolation gap is created when the contacts separate vertically in a vertical break isolator. The isolator's vertical movement reduces its vulnerability to environmental factors, such as wind and debris, which can affect horizontal mechanisms. Substations and outdoor installations requiring high voltage break isolators are prevalent where environmental conditions are significant.

Horizontal Break Isolator: Horizontal break isolators separate contacts visually by opening horizontally. Medium- to high-voltage isolators are used in these applications. A straightforward and visible isolation mechanism is provided by the horizontal movement of the contacts. Remote control is available for these isolators or they can be operated manually. In substations and transmission lines, horizontal break isolators are commonly used when a clear isolation point is needed.

Applications

Power Distribution Systems: Ensure the safe maintenance and operation of power distribution systems by using electrical isolators. Parts of the network are isolated with them, including transformers, circuit breakers, and feeders. Isolators protect systems from electrical hazards by disconnecting these components from the live parts during routine maintenance or in the event of a fault. Electric shock is prevented by this type of isolation, allowing technicians to perform repairs or inspections safely.

High Voltage Transmission Lines: A high voltage transmission line often uses electrical isolators during maintenance or emergencies to ensure safe disconnection. Transmission lines are segmented into manageable sections with these structures at critical points, such as at the entrances and exits of substations. In addition to reducing downtime and improving power supply reliability, this segmentation facilitates fault isolation and maintenance.

Substations: Transformers, circuit breakers, and busbars can be isolated using isolators in substations. A substation is a crucial node of a power grid that changes voltage levels and routes power between parts. Substation isolation ensures that sectional de-energization for maintenance will not affect the substation as a whole. Additionally, they provide an additional layer of safety by creating a visible break in the circuit.

Industrial Applications: For safe maintenance and repair, electrical isolators are used in industrial settings. There are usually a lot of machines and control panels in factories and industrial plants with complex electrical systems. Isolators allow maintenance personnel to work without risk of electric shock by safely disconnecting individual machines from the power supply. As well as isolating faulty equipment, they protect the entire system by preventing damage.

Renewable Energy Systems: Among the most important components of renewable energy systems are electrical isolators. For maintenance or in the event of a fault, solar power systems use isolators to separate photovoltaics (PVs) from inverters. For safe servicing of turbines and other components in wind power systems, isolators are used. It is possible to maintain the system while it is still generating power without risking electrical hazards.

Railway Electrification Systems: A third rail or overhead catenary section of a railway system is isolated with electrical isolators. It is necessary to isolate the trains during maintenance work on the electrification infrastructure. It is possible to perform maintenance on isolated sections without interfering with the operation of the entire railway line, thus eliminating disruptions to train services and ensuring the safety of maintenance personnel.

Wrapping Up

Modern electrical systems require electrical isolators to ensure safety and operational efficiency. These devices are designed for the purpose of disconnecting electrical circuits for maintenance, repair, and fault isolation. It is important to note that each type of isolator has unique advantages tailored to specific requirements and environments, including the single break, double break, pantograph, vertical break, horizontal break, center break, and double side break isolators. 

Their essential role in power distribution systems, high voltage transmission lines, substations, industrial environments, renewable energy systems, railway electrification, and telecommunications is evident from understanding their principles. By selecting and applying electrical isolators properly, electrical infrastructure can be made more safe, reliable, and efficient, ensuring seamless network operation.