What isa three-phase three-wire power filter and a three-phase four-wire filter?
Three-phase three-wire is the three live wires of ABC phase.
Three-phase four-wire is to add a neutral wire to three-phase three-wire to become four wires.
Circuit structure and filtering principle of three-phase power filter
The power supply filter is a filter circuit composed of capacitors, inductors and resistors, also known as LC filter, also known as: EMI power filter. It is a passive two-way network, one end of which is the power supply and the other end is the load. The principle of a power supply filter is an impedance adaptation network: the greater the impedance adaptation between the input and output sides of the power filter and the power supply and load sides, the more effective it will be in attenuating electromagnetic interference. The filter can effectively filter the frequency point of a specific frequency in the power line or the frequency outside the frequency point, obtain a power signal of a specific frequency, or eliminate the power signal of a specific frequency.
What does the three-phase power filter do?
The capacitor in the filter circuit is to filter out high-frequency clutter, and the coil is to stabilize the current and obtain clean voltage and stable power.
Some precision equipment has strict requirements on the frequency of the power supply when working. The frequency standard of my country’s mains power is 50Hz. However, when the power grid transmits and transforms electric energy, there will be more or less high-order harmonics. These harmonics are Caused by some non-linear components in the network, in order to ensure the normal operation of the equipment, installing a power supply filter will greatly reduce the high-frequency electromagnetic interference in the power supply, reduce the interference to peripheral equipment and signal transmission to the allowable range, and create Good electromagnetic compatibility environment.
The function of the power line filter is to enable the equipment to meet the requirements for conducted emission and conducted sensitivity in the electromagnetic compatibility standards. The power line filter is also important in suppressing strong radiated interference from the equipment. Strictly speaking, the function of the power line filter is to reduce the electromagnetic interference generated by the equipment itself from entering the power line, and at the same time reduce the interference from the power line entering the equipment. The power line filter is a low-pass filter that allows DC or 50Hz operating current to pass, but does not allow higher frequency electromagnetic interference current to pass.
Those electrical equipment can produce strong electromagnetic interference:
Equipment containing pulse circuits (microprocessors), switching power supplies, equipment using thyristors, variable frequency speed regulators, AC and DC motors. Sensitive circuits (equipment susceptible to interference) such as: equipment using microprocessors, small signal analog circuits, etc.
Manufacturing on EMI Filter
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