Isolation switches are commonly used electrical appliances in high-voltage switch cabinets, and they play an isolating role in the circuit.Its working principle and structure are relatively simple. It is generally used in the contact part of wall switches, relays, circuit breakers and other equipment to ensure the reliable on and off of the circuit. It is used in large quantities and has high requirements for working reliability. It has a great impact on the design, establishment and safe operation of substations and power plants. It plays an important role in the fields of electrical, electronic and mechanical fields.
Generally, a set of isolation switches are installed on the front and back sides of the circuit breaker. The purpose is to isolate the circuit breaker from the power supply and form an obvious disconnection point; because the original circuit breaker uses an oil circuit breaker, the oil circuit breaker needs to be frequently inspected, so there must be obvious disconnection points on both sides to facilitate inspection; Under normal circumstances, the outlet cabinet is powered from the upper busbar through the switch cabinet. A set of isolation switches is needed in front of the circuit breaker to isolate it from the power supply, but sometimes, there is also the possibility of incoming power behind the circuit breaker, such as reverse transmission through other loops, capacitors and other devices, so a set of isolation switches is also needed behind the circuit breaker.
The isolation switch is mainly used to reliably isolate the part of the high-voltage power distribution device that needs to be shut down from the live part to ensure the safety of the maintenance work. The contacts of the isolation switch are all exposed to the air and have a clear disconnection point. The isolation switch does not have an arc extinguishing device, so it cannot be used to cut off the load current or short-circuit current. Otherwise, under the action of high voltage, the disconnection point will generate a strong arc, which is difficult to extinguish by itself, and may even cause arcing, burn equipment, and endanger personal safety. This is the so-called serious accident of pulling the isolation switch with load. The isolation switch can also be used to switch certain circuits to change the operation mode of the system.
High and low voltage circuit breakers are a kind of electrical protection device. It has a wide variety of types and has arc extinguishing devices. The full name of the air switch is air-type low-voltage circuit breaker, which is a type of circuit breaker mainly used in low-voltage circuits. Because it uses air as a medium to extinguish the arc, it is called an air-type low-voltage circuit breaker, referred to as an air switch. The power distribution in our ordinary home buildings is basically air switches.
The isolation switch is a high-voltage switchgear mainly used in high-voltage circuits. It is a switchgear without an arc extinguishing device. It is mainly used to disconnect the circuit without load current and isolate the power supply. There is an obvious disconnection point in the open state to ensure the safe maintenance of other electrical equipment. In the closed state, it can reliably pass the normal load current and short-circuit fault current. Because it does not have a special arc extinguishing device, it cannot cut off the load current and short-circuit current. Therefore, the isolation switch can only be operated when the circuit has been disconnected by the circuit breaker. It is strictly forbidden to operate with load to avoid serious equipment and personal accidents. Only voltage transformers, lightning arresters, no-load transformers with excitation current not exceeding 2A, and no-load lines with current not exceeding 5A can be directly operated with isolation switches.
In power applications, circuit breakers and isolation switches are mostly used in conjunction, circuit breakers are used to switch on and off load currents, and isolation switches are used to form obvious disconnection points.
Summarize
Although isolation switches and circuit breakers are similar in some aspects, such as both are used for isolation functions in circuits, there are some important differences between their design, functions and uses. isolation switches are mainly used to isolate circuits, while circuit breakers are used to protect circuits and cut off current when a fault occurs. Understanding the difference between them can help you correctly select the device that is suitable for a specific application scenario and ensure the normal operation and safety of the power system.
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