The supplier of frequency converter supporting equipment reminds you that the reactor installed on the output side of the frequency converter to improve the power factor and suppress harmonic current can reduce the noise and vibration of the motor. When the connection between the frequency converter and the motor is long, it can suppress surges on the wires.
The following options can be added to the input side of the frequency converter:
1) InputReactor is an input reactor that can suppress harmonic currents, improve power factor, and reduce the impact of surge voltage and current in the input circuit on the frequency converter, as well as weaken the influence of power supply voltage imbalance. In general, a line reactor must be added.
2) The input EMC filter is used to reduce and suppress electromagnetic interference generated by the frequency converter. There are two types of EMC filters, A-grade and B-grade filters. EMCA level filters are used in the second category of industrial applications and meet the EN50011A level standard. EMCB level filters are commonly used in the first category of applications, namely civilian and light industrial applications, and meet the EN50011B level standard.
There are several options available on the output side of the frequency converter, including:
1) Output reactor: When the length of the cable output from the frequency converter to the motor exceeds the specified value of the product, an output reactor should be added to compensate for the charging and discharging effects of the coupling capacitance during the operation of the long cable of the motor, in order to avoid overcurrent of the frequency converter. There are two types of output reactors. One type is the iron core reactor, which is used when the carrier frequency of the frequency converter is less than 3KHZ. Another type of output reactor is ferrite type, which is used when the carrier frequency of the frequency converter is less than 6KHZ. The purpose of adding an output reactor to the output terminal of the frequency converter is to increase the distance between the frequency converter and the motor. The output reactor can effectively suppress the instantaneous high voltage generated by the IGBT switch of the frequency converter, reducing the adverse effects of this voltage on cable insulation and the motor. At the same time, in order to increase the distance between the frequency converter and the motor, the cable can be appropriately thickened to increase the insulation strength of the cable, and unshielded cables should be selected as much as possible.
2) Outputdv/dtfilter outputs dv/dt reactors. The purpose of outputting dv/dt reactors is to limit the rise rate of the output voltage of the frequency converter to ensure the normal insulation of the motor.
3) Sinusoidal filters are sine wave filters that approximate the output voltage and current of the frequency converter to sine waves, reducing the motor harmonic domain change coefficient and motor insulation pressure
Abnormal handling of series reactors
Capacitor series reactors generally adopt epoxy glass fiber multi encapsulated parallel structures. According to the characteristics of the installation site, three-phase vertical stacking, three-phase horizontal "△" and three-phase horizontal "-" distribution are adopted.
Multiple incidents of series reactor operation have occurred in substations in the southern region, where the outer insulation layer has cracked, and in severe cases, it has affected safe operation Under the organization of wind regulation, the manufacturer and operation management department conducted a detailed analysis Under the organization of the network dispatching, the manufacturer and the operation management department carried out a detailed analysis. By comparing different operating conditions and climatic reasons, it was found that because the capacitor bank was operating at rated load, the operating current was large, and the load current in normal operation was up to 1000A. Under the action of such large current, the operating temperature of the series reactor rose close to 100 ℃. If it was in rainstorm when exiting the operation, the reactor surface temperature dropped rapidly, and the change of thermal expansion and cold contraction in a short time was the main reason for the surface cracking of the series reactor Therefore, in the job requirements, the network debugging requires on-site duty personnel to minimize changes in the operation mode of capacitors during sudden weather changes.
There have been incidents of series reactors overheating and catching fire in the system. The cause analysis shows that the capacitor bank operates with a high load current, and when the contact between the conductor joints is not tight and the contact resistance is too high, overheating occurs. When the ignition point of the fiber material is exceeded, combustion occurs.
The hollow structure in the middle of the series reactor determines that it is an ideal resting place for various birds to build nests. If a large amount of hay and tree branches are not cleaned up in time, it may cause a fire or grounding short circuit in the reactor.