The low-pass filter can absorb most of the " burrs " of the power supply
The low-pass filter can absorb most of the " burrs " of the power supply . L1 and L2 in the figure are used to suppress high-frequency differential mode voltage . L1 and L2 are reversely wound on the same magnetic ring with equal-length wires , 50HZ The magnetic fluxes generated by the power frequency current in the magnetic ring cancel each other out, and the magnetic ring will not be saturated.
The magnetic flux generated by the common mode interference current in the two lines is superimposed in this ring, and the common mode interference is blocked by L3 and L4. In the figure, C1 and C2 are used to filter out the common mode interference voltage, and C3 is used to filter Differential mode interference voltage.
R is a varistor, and its breakdown voltage is slightly higher than the highest voltage of the normal operation of the power supply, which is usually quite open.(Allen Bradley 1756-L71S GuardLogix Controller, Siemens 6ES7134-4GB01-0AB0 ET200S Electronics Module,B&R X20CP1585 CPU New, Allen Bradley 1734-EP24DC Expansion Power Supply ) When it encounters a spike interference pulse, it is broken down, and the interference voltage is clamped by the varistor. At this time, the terminal voltage of the varistor is equal to its breakdown voltage.
The high-frequency interference signal is not transmitted through the coupling of the transformer windings, but through the distributed capacitance between the primary and secondary windings. Adding a shielding layer between the primary and secondary windings and grounding it together with the iron core can reduce the distributed capacitance between the windings and improve the ability to resist high-frequency interference.
Power filter products can also be used, such as the power filter of Beijing Zhongshi Company, which has good common mode filter, differential mode filter performance and high-frequency interference suppression performance, and can effectively suppress the line-to-line and line-to -ground. interference, its products can be used for AC single-phase, three-phase power and DC power. C/D series high-performance filters are suitable for electronic equipment with transient
The interested persons of mentioned parts may relate with me, price liberally. --
Vivi (sh_plc@163.com).