Bus disconnector. Who can introduce me? Can anyone who knows the inside story tell me?

Isolating switch is different from idling switch.

Disconnector means that there is an insulation distance between contacts that meets the specified requirements, and the switch has obvious disconnection signs when it is in the separation position; When closed, it can withstand the current under normal circuit conditions and the current under abnormal conditions (such as short circuit) within the specified time.

The disconnector we mentioned generally refers to the high-voltage disconnector, that is, the disconnector with rated voltage of 1kv or above, which is usually referred to as the disconnector. It is the most widely used high-voltage switchgear with simple working principle and structure. However, due to its large usage and high reliability requirements, it has a great impact on the design, construction and safe operation of substations and power plants. The main feature of circuit breaker is that it has no arc extinguishing ability and can only open and close the circuit without load current. The main functions are:

1) After the brake is disconnected, establish a reliable insulation gap, separate the equipment or line to be repaired from the power supply, and have obvious disconnection points to ensure the safety of maintenance personnel and equipment.

2) Switch lines according to operation needs.

3) It can be used to shunt and merge small currents in lines, such as the charging current of bushings, buses, connectors and short cables, the capacitance current of switching voltage equalizing capacitors, the circulating current when switching double buses and the excitation current of voltage transformers.

4) According to the specific conditions of different structural types, it can be used to divide and combine the no-load excitation current of a transformer with a certain capacity.

According to different installation methods, high voltage disconnectors can be divided into outdoor high voltage disconnectors and indoor high voltage disconnectors. Outdoor high-voltage disconnector refers to a high-voltage disconnector which can withstand the influence of wind, rain, snow, pollution, condensation, ice and thick frost, and is suitable for installation on the terrace. According to the different structure of insulation pillar, it can be divided into single-column isolating switch, double-column isolating switch and three-column isolating switch. Among them, the single-column circuit breaker directly uses the vertical space below the overhead bus as the electrical insulation of the fracture. Therefore, the advantages are obvious, that is, the floor space is saved, the leads are reduced, and the opening and closing state is particularly clear. In the case of EHV transmission, the effect of saving floor space is more obvious after using single-column circuit breaker in substation.

Among low-voltage equipment, it is mainly suitable for low-voltage terminal distribution systems such as houses and buildings. Main function: disconnect and connect the line with load.

Isolation function

Selection of isolating switch:

The disconnector is arranged on the main wiring to ensure that the obvious fracture is isolated from the live part when the line and equipment are overhauled. Because the disconnector has no arc extinguishing device, its breaking ability is low. When operating the disconnector, the switching operation sequence must be observed, that is, the disconnector on the bus side should be closed first, then the disconnector on the line side should be closed, and finally the circuit breaker should be closed. In case of power failure, the opposite is true.

Configuration of disconnector:

1, disconnectors should be installed on both sides of the circuit breaker, so as to form obvious fracture and power isolation when the circuit breaker is overhauled.

2. Ordinary transformers whose neutral points are directly grounded shall be grounded through disconnectors.

3. The lightning arrester and voltage transformer on the bus should share a set of isolating switch to ensure the maintenance safety of electrical appliances and buses, and each bus should be equipped with 1-2 grounding breaker.

4. The lightning arrester connected to the outgoing line or neutral point of the transformer need not be equipped with an isolating switch.

5. When there is no power supply on the user side of the feeder, the disconnector shall not be installed on the side of the circuit breaker leading to the user. But in order to prevent lightning overvoltage, it can also be installed.

Air switch is a kind of switch that will trip as long as there is a short circuit.

There are three tripping modes: thermal tripping, electromagnetic tripping and compound tripping.

When the line is generally overloaded, the overload current can not make the electromagnetic trip work, but it can make the thermal element generate a certain amount of heat, make the bimetal bend upward when heated, push the lever to make the hook disengage from the lock, disconnect the main contact and cut off the power supply.

When the line is short-circuited or the current is seriously overloaded, the short-circuit current exceeds the instantaneous tripping setting current value, and the electromagnetic release generates enough suction force to attract the armature to impact the lever, so that the hook rotates upward around the rotating shaft seat and disengages from the lock catch, and the lock catch disconnects three pairs of main contacts and cuts off the power supply under the action of the reaction spring.

The tripping mechanism of the switch is a set of connecting rod devices. When the main contact is closed by the operating mechanism, it is locked in the closed position by the locking hook. If there is a fault in the circuit, the related trip will release the lock hook in the trip mechanism, so the main contact will be quickly disconnected under the action of the trip spring. According to the different protection functions, the release can be divided into overcurrent release and pressure loss release.

Under normal circumstances, the armature of the overcurrent release is released; When serious overload or short circuit fault occurs, the coil connected in series with the main circuit will generate strong electromagnetic attraction, which will attract the street rail downwards and push the unlocking hook to disconnect the main contact. The working principle of undervoltage release is just the opposite. When the voltage is normal, electromagnetic attraction attracts the armature and the main contact is closed. Once the voltage drops seriously or the power is cut off, the armature is released and the main contact is disconnected. When the power supply voltage returns to normal, it must be switched on again to work, thus realizing voltage loss protection.

Because there are many insulation methods, such as oil switch, vacuum switch and other inert gas (sulfur hexafluoride gas) switches. Air switch is a switch that uses air to extinguish arc, so it is called air switch. Air is used to extinguish the arc generated during the switching process. So it's called an air switch.