How to Measure the Inductance of a 3 Phase Reactor?
Compared with the single-phase reactor, the 3 phase reactor can limit the current impact caused in the power grid voltage mutation and the overvoltage operation, so as to effectively protect the frequency converter and improve its power factor. In addition the difference in application, the structure of the three-phase reactor is characteristic as well. Its iron core adopts the high-quality low-loss imported cold-rolled oriented silicon steel sheet. The coil adopts H-grade or C-grade enamel-cover or glass fiber cover the flat copper wire for winding. The wires are arranged tightly and evenly, and the entire reactor is stoved in vacuum status after being immersed in H grade insulation varnish. It basically generates no noise in operation.
High-quality 3 phase reactor puts forward corresponding requirement to the application environment. In terms of temperature and humidity, temperature of the ambient air should not exceed +45℃, and the average maximum relative humidity of the wettest month is 90%. The altitude should not exceed 2000m. Meanwhile, it should be kept from the rain and snow invasion, free of strenuous vibration and impact. It must be placed in the medium without any explosion risk. The medium should have no gas or electric dust which will collide the metal or damage the insulation.
The technology about the 3 phase reactor is like this: its rated insulation level is 3KV/min; the temperature rise limit of various reactor components: coil less than 95K, iron core less than 85K. the reactance difference of any two phases of the three-phase reactor is no more than ±3%; the temperature resistance grade is H; and the noise is no more than 50dB.
In addition to the aforementioned fundamental knowledge, it is required to comprehend how to measure the inductance of the three-phase reactor. As a matter of fact, the impedance amplitude in measurement includes the resistance and inductance component of the impedance. However, the resistance component might be smaller than the inductance component. Assuming if the true effective value measuring instrument is used to measure the current and voltage of the 3-phase reactor, the impedance is estimated to be affected by the harmonic voltage generated by the power substation.
In addition, it can be compensated by measuring the resistance of the inductance and eliminating the component from the measurement. The resistance is probably too low, thus being unable to be measured by the ohmmeter easily. On the contrary, the inductance is disconnected with the AC, and the table-model DC power supply of constant flow is adopted, and a pair of DC current is forced through the inductance. And the DC current and voltage on the inductance will be measured. If it is still required to know the precision inductance resistance of the three-phase reactor, the pure sinusoidal voltage can be used, or the unknown inductance can be connected in parallel with the known precision capacitance, and the frequency of the resonance peak can be measured.
With the 3 phase reactor, in regulating the speed of the original power frequency excitation, the establishment of the feedback voltage maintains the excitation current in the excitation coil to be in a rather small amplitude, which will basically not exceed the maximum value. It can reach the maximum value unless it is in full-speed operation status. The three-phase reactor is widely used in the elevator, wind power generation, solar power generation, railroad engine, metro, machine tool, welding machine, industrial washing machine, airplane, ship, electromechanical laboratory of the university and other fields.
