Low Voltage: These isolators are designed to withstand voltage up to 11KV.These are used in combination with a circuit breaker. In case the main bus side isolator is unavailable due to some fault/maintenance transfer bus isolator is used. Transfer Bus Side Isolator: In an electrical system for reliability main or transfer bus is used.A feeder is a line that carries power from the Substation to the distribution system. Lineside Isolator: These are connected between the line and any feeder.Whenever there is a need for repair or replacement of any bus, they are operated. Bus Side Isolator: These are connected to the main buses in the substation.So, the isolator on both sides of the circuit breaker allows essential replacement and services requirements to be performed safely. Isolators are generally used on both sides of the circuit breaker, this measure is taken just to ensure extra safety and protection because in a power system incoming and outgoing lines can have multiple sources of power, and disconnecting one side is sometimes not enough. Horizontal double break isolator in substations use is abundant. It is designed in small compact cases so that it can be used in domestic scale wiring systems. Miniature circuit breaker (MCB) as apparent from the name is designed for low power requirements such as homes and offices. This type of pantograph isolator is widely used in electric trains to obtain electricity from overhead transmission lines. In a pantograph type isolator, both terminals at each side connect and disconnect only because of the forces of stress or tension, and usually is no locking mechanism. In a single break isolator, only one terminal connects and disconnects whereas in a double break isolator both terminals at each side connect and disconnect because the central terminal is moveable. Lineside isolator: It is generally located at the line side of the feeder.Transfer bus side isolator: It directly connects to the transfer bus.Bus side isolator: It directly connects to the main bus.Isolators based on Application can be classified into four types.ĭepending upon the position in the power system, the Isolators can further be categorized into the following three types according to their placement in the power system. Choice of electrical isolators depends upon the requirement and application and based on the placement in the system. There are various kinds of isolators available in the market. And It can be operated manually or it can be actuated automatically. It can be seen that it is a physical and mechanical system. The picture below shows the isolators in a disconnected state within a power substation. And for the reverse process, the first isolator is closed then the circuit breaker is closed and the circuit is reconnected. In high-voltage power systems, isolators are used in conjunction with circuit breakers to provide an extra layer of safety.Ī first circuit breaker is opened which disconnects the circuit then the isolator is also opened. Commonly used isolators are not intended to stop current during a fault to eliminate high voltage arcs, which occur due to disturbance in electric conductors. Isolator switches, in particular, are used in power grids and substations to efficiently isolate very high voltage apparatuses such as transformers and circuit-breakers when they are due for maintenance. And here isolators are particularly useful in eliminating grounding loops, such as lowering the risk of accidental paths for electric current to flow towards the ground. This figure shows isolators being used as insulators in transmission lines to isolate transmission towers from the conductor.
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