The operating structure of the high-voltage circuit breaker - Delixi

1. Classification of switch operation organization

At present, the switches we encounter are generally divided into many types, such as oil-rich type (old model, now you can't see it at all), oil-poor type (some user stations also have it), SF6, vacuum, GIS (combined electrical appliances) and so on. These are all about the arc extinguishing medium of the switch. For us, the operating mechanism of the switch is closely related.

The type of tissue can be divided into electromagnetic operation organization (relatively old, generally using circuit breaker in the case of more or less oil); Tension spring manipulation tissue (currently the most common, SF6, vacuum, and GIS are generally equipped with this structure); Recently, ABB introduced new permanent magnet operating organizations such as the VM1 vacuum circuit breaker.

　　 The operating structure of the high-voltage circuit breaker - Delixi

The operating structure of the high-voltage circuit breaker - Delixi

2. Organization of electromagnetic operation

The electromagnetic operation organization completely relies on the electromagnetic attraction generated by the closing current flowing through the closing coil to close and compress the tripping tension spring, which is mainly used to supply energy when tripping. Therefore, the tripping current of this type of operating organization is very small, but the closing current is very large, and it can reach more than 100 amperes in an instant.

This is why the DC system of the substation switches the bus on and off to control the bus. The closed bus supplies the switching power supply, and the control bus supplies power to the control circuit.

The closing bus is directly hung on the battery pack, and the closing bus voltage is the voltage of the battery pack (generally about 240V). When closed, the discharge effect of the battery is used to supply a large current instantaneously, and at the same time, the voltage drops sharply when closed. The control bus is connected by a silicon chain to step down and close the bus (generally controlled at 220V), and the voltage stability of the control bus will not be affected when closing. Because the closing current of the electromagnetic operation organization is very large, the maintenance closing circuit is not directly connected to the closing coil, but to the closing contactor. The trip circuit is connected directly to the trip coil.

The closing contactor coil is generally of the voltage type and has a large resistance (usually several thousand ohms). When cooperating with this circuit maintenance, it is necessary to note that the closing generally cannot be activated. It's not a big deal, though. The TBJ that sticks to the stroke can generally be activated, so the anti-jump function is still available. This tissue has a long closing time (120 ms - 200 ms) and a short disconnection time (60 - 80 ms).

3. Tension spring operation organization

This type of tissue is currently the most commonly used tissue, and its connection and disconnection rely on the tension spring to supply energy. The trip coil only supplies the energy to pull out the tension spring positioning pin, so the trip current is generally small. The tension spring is compressed by the energy storage motor to store energy.

As far as the flexible operation organization is concerned, the closing bus is mainly for the energy storage motor, and the current is not large, so there is not much difference between the closing bus and the control bus. In general, there is nothing special to pay attention to when it comes to maintaining and cooperating with it.

4. Permanent magnet operation organization

The permanent magnet operating structure is a kind of organization applied by ABB to the domestic market, and was first applied to its VM1 10kV vacuum circuit breaker. The principle is similar to that of the electromagnetic type. The drive shaft is made of permanent magnets with electromagnetic coils around the permanent magnets.

Under normal conditions, the solenoid coil is not electrified. When a switch is to be opened or closed, the principle of magnetic attraction or extrusion is used to drive the disconnection or closure by changing the polarity of the coil.

Although this current is not small, the switch "stores energy" through a large capacitor, and the capacitor discharges to supply the high current during operation. This kind of structure has the advantage of small size and few transmission mechanical parts, so its reliability is better than that of elastic structure.

In cooperation with our maintenance device, our trip circuit drives a high-impedance solid state relay, in fact, we only need to supply it with an action pulse. Therefore, regarding this switch, the insistence circuit must not be activated, and the maintenance anti-jump will not be activated (the organization itself has anti-jumping).

However, it should be noted that because the operating voltage of the solid state relay is high, the conventional planning TW negative circuit and closing circuit are connected together, which will not cause the solid state relay to operate, but may cause the azimuth relay to fail to start because the partial voltage is too large. This situation has also been encountered in the field, and the detailed analysis and processing process can be found in the debugging examples section of this article, which is depicted in detail.

There are also products of permanent magnet operating organization in China, but the quality has not been very good in the past. After the quality improvement in recent years, it has been gradually introduced to the market. Considering the cost, the domestic permanent magnet organization is generally not equipped with capacitors, and the current is directly supplied by the closing bus. Our operating organization drives the on-off contactor (generally selected for the current), which can generally be activated to insist and prevent jumping.

5. FS type "switch" and others

The above we are talking about circuit breakers (commonly known as switches), but in the process of power plant construction, you may encounter the FS switches that users say. FS is actually the abbreviation of load switch + fast fuse.

Because Delixi switch is expensive, in order to save money, this FS circuit is adopted. The normal current is intercepted by the load switch, and the current is blocked by the fast fuse when there is a fault.

This kind of circuit is very common in the power system of the 6kV plant of the power plant. Cooperative circuit maintenance often requires that when the fault current is greater than the breaking current promised by the load switch, it is forbidden to trip or delay, so that the fast fuse can block the current. Some power plant users may not want to maintain the sticking circuitry.

Because of the poor quality of the switch, the auxiliary contact may not be in place, and once the insistence circuit is activated, it is necessary to turn over the auxiliary contact of the circuit breaker before returning, otherwise the trip current will be added to the trip circuit until the coil is burned out.

The opening and closing coil is planned according to short-term energization, and it is easy to burn out when the current is applied for a long time. And we must have a sticking circuit, otherwise it is easy to burn out the maintenance contacts.

Of course, if the user in the field insists, the insistence circuit can also be removed. A simple way to do this is to block the connection between the normally open contacts of the latching relay and the positive control bus on the circuit board.

At the commissioning site, it is necessary to note that if the switch is flipped open and closed, the bearing indicator will be completely silenced. (If the tension spring is not stored when the tension spring is swept, and the panel shows the tension spring is not energy storage alarm), it is necessary to immediately close the control power supply to prevent the switch coil from burning. This is a fundamental principle to keep in mind in the field.

The operating structure of the high-voltage circuit breaker - Delixi

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