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Current-limiting reactor

Generally used for power distribution lines. The branch feeders from the same bus usually have a series of current-limiting reactors in order to limit the short-circuit current of the feeder and maintain the bus voltage so as not to be too low due to the feeder short.


Inverter Reactor Working Temperature:-25~55℃
Inverter Power Reactor Material:Copper or Aluminum
Inverter Power Reactor Type:Dry type iron core
Inverter Power Reactor Rated Voltage:220V-380V


Current-limiting reactors are inductive components that limit the use of closing inrush currents, higher harmonics, and short-circuit fault currents in the system. Reactors are made of copper or aluminum coils. Cooling methods include oil-immersed and dry self-cooling methods. The structure of the support includes cement pillar type and clamping type.


1.Improve the input current wave resulted by capacitor harmonics

2.Reduce and prevent the rectification bridge being damaged and capacitor being overheating due to surging current.

3.Improve power factor, reduce DC busbar AC pulse.

4.Restrict the transient change of system voltage.

Function and role

(1) Line reactor. In order to use a light circuit breaker and reduce the cross section of the feeder cable, the line reactor is often connected in series to the cable feeder. When a short circuit occurs after the line reactor, it not only limits the short-circuit current, but also maintains a high residual voltage on the bus to improve the reliability of the power supply. Because the cable has a small reactance value and distributed capacitance, even if a short circuit occurs at the end of the cable, a short-circuit current about the same size as the bus short circuit will be generated.

(2) Bus reactor. The bus reactor is connected in series at the section of the generator voltage bus or the low-voltage side of the main transformer. It is used to limit the short-circuit current during short-circuits inside and outside the plant. It is also called a bus section reactor. When a short circuit occurs on the line or on one bus, it can limit the short-circuit current provided by the other bus. If the requirements can be met, the installation of a reactor on each line can be omitted to save engineering investment, but it has a smaller effect of limiting short-circuit current.

(3) Transformer loop reactor. It is installed in the transformer circuit to limit the short-circuit current so that the transformer circuit can use light circuit breakers.


The reactor used in the power grid is essentially a hollow coil without magnetically permeable material. It can be arranged into three types of assembly: vertical, horizontal and glyph. When a short circuit occurs in the power system, a large amount of short circuit current is generated. Without restrictions, it is very difficult to maintain the dynamic and thermal stability of electrical equipment. Therefore, in order to meet the requirements of the breaking capacity of some circuit breakers, a reactor is often connected in series at the outgoing circuit breaker to increase the short-circuit impedance and limit the short-circuit current.

Because the reactor is used, the voltage drop across the reactor is large when a short circuit occurs, so it also plays a role in maintaining the voltage level of the bus, making the voltage fluctuations on the bus smaller, and ensuring user electrical equipment on non-faulty lines.


Current-limiting reactors can be divided into concrete column-type current-limiting reactors and dry-type hollow current-limiting reactors according to different structural forms. They are also divided into ordinary reactors and split reactors.
(1) Concrete column type current limiting reactor. In indoor power distribution devices with a voltage of 6 to 10 kV, concrete column type current limiting reactors (also known as cement reactors) are widely used in China. It consists of windings, cement pillars and pillar insulators.
The winding consists of a multi-core aluminum wire insulated with gauze and paper wrapped in a spiral-shaped pie coil on the same plane. In order to avoid saturation of the magnetic circuit and keep the inductance value unchanged, a hollow inductor winding without an iron core is often used.
A bracket is provided at a uniform and symmetrical position along the circumference of the winding, and cement is cast on the bracket to become a cement pillar, which serves as the skeleton of the reactor, and the winding is fixed on the skeleton. After pouring and drying in a vacuum tank, the cement is highly hygroscopic. Therefore, it is necessary to paint after drying to prevent water from immersing in the cement.
The cement reactor has the advantages of simple structure, safe operation, high reliability, good linearity of the reactance value, simple maintenance, non-flammability, and cheap price. Its main disadvantage is its large size and bulk.

(2) Split reactor. In order to limit the short-circuit current and make the busbar have a higher residual voltage, a larger reactor is required; and in order to reduce the voltage and power loss in the reactor during normal operation, a smaller reactor is required. This is a contradiction, and the use of a split reactor can help resolve this contradiction.
The split reactor is similar in structure to the ordinary reactor, except that there is a tap in the center of the winding, and the winding forms two branches, and its rated current and self-inductance reactance are equal. Generally, the middle tap is used to connect the power supply, and the two branches are connected to two groups of approximately equal loads. Due to the magnetic coupling of the two branches, different reactance values ​​will be generated during normal operation and when one of the branches is short-circuited.
If the reactance values ​​of the split reactor and the ordinary reactor are equal, the current limiting effect of the two in the short circuit is the same. However, during normal operation, the voltage loss of the split reactor is only half that of ordinary reactors, and double the number of outlets than ordinary reactors, thereby reducing the number of reactors, reducing equipment investment and floor space, and is therefore widely used. .

(3) Dry-type hollow current-limiting reactor. This is a new type of current-limiting reactor developed in recent years. Its windings are wound with multiple parallel small wires and multiple strands in parallel. The inter-turn insulation strength is high, so the loss is much lower than that of cement reactors. It is encapsulated with epoxy resin-impregnated glass fiber and solidified at high temperature. Light weight, low noise, high mechanical strength, can withstand the impact of large short-circuit currents; there are ventilation channels between the winding layers, and the natural convection cooling performance is good, and the current is evenly distributed in each layer, with high dynamic and thermal stability; the outer surface of the reactor Coated with a special anti-ultraviolet weather-resistant resin coating, it can withstand the harsh weather conditions outdoors and can be used indoors and outdoors.





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