What Is an AC Reactor?
An AC reactor is a type of element inserted into an AC electrical or electronic circuit.
They are mainly installed to improve the power factor of inverters and to suppress harmonics.
Uses of AC Reactors
AC reactors are used in AC circuits. Specific uses are as follows:
- Air conditioning equipment driven by inverters.
- Machine tools and trains.
- Electric vehicles.
To realize a decarbonized society, which has become a hot topic in recent years, more and more equipment in the industrial world uses electricity that does not directly generate CO2 emissions. AC reactors are in increasing demand for AC power transmission and AC to DC conversion devices such as inverters.
Principle of AC Reactors
The AC reactor consists almost entirely of a coil. It consists of a coil, insulation filler, girders, and other components. A coil is a component made by winding an electric wire multiple times. Coils inserted in power supplies are also called choke coils.
There are two types of reactors: an iron-core type reactor, in which the wire is wound around an iron core, and an air-core reactor, which does not have an iron core.
Insulating filler is a material used to insulate electricity. Mainly, insulating resin and oil paper are used for this purpose. Since coils and mounts are made of metal, the heat resistance temperature of the reactor is generally determined by the insulating filler.
Since a coil is a mass of metal wires wound several times, it is heavy compared to its volume. Therefore, they are supported by metal mounts, which in many cases have holes drilled in them to sew them to the floor or wall.
Other Information on AC Reactors
1. Difference Between AC Reactor and DC Reactor
The “AC” in AC reactors stands for “Alternating Current”. On the other hand, there is an element called a DC reactor that handles “Direct Current”. Both are used for inverters.
Inverters convert AC to DC internally and switch the DC to output AC.
DC reactors are typically connected to the internal DC circuit of the inverter. AC reactors are installed when harmonics are still a problem.
For small load circuits where lagging power factor and harmonics do not need to be taken into account, both reactors may be omitted.
2. Types of Reactors
Reactors have different names depending on their applications.
Current-limiting reactor
Electric circuits are equipped with circuit breakers that can safely interrupt the circuit in the event of a short-circuit accident.
Since reactors have current-slowing characteristics, current-limiting reactors are installed in series with the circuit to limit the current at the time of a short circuit.
Shunt Reactor
Shunt reactors are reactors for power factor correction. When power consumption is low at night, for example, the transmission and distribution lines may advance phase. By installing a shunt reactor in parallel with the circuit, the power factor of the power line can be improved by slowing down the phase advance.
AC / DC reactor
As mentioned above, these reactors are installed to improve the power factor of inverters and suppress harmonics. Although these reactors differ in scale and materials, there is no difference in structure. All reactors have a structure in which wires are wound in a coil.