In daily life, we can often see filters in various electrical appliances such as radios, televisions, and stereos. How much do you know about filters? How much do you know about single-phase power filters? This article mainly introduces the relevant knowledge about single-phase power filters.
filterThe filter is a frequency selection device that can pass specific frequency components in the signal while greatly attenuating other frequency components. Using the frequency selection function of the filter, interference noise can be filtered out or spectrum analysis can be performed. In other words, any device or system that can pass specific frequency components in a signal while greatly attenuating or suppressing other frequency components is called a filter.
1. Separate useful signals from noise to improve signal anti-interference and signal-to-noise ratio;
2. Filter out uninteresting frequency components to improve analysis accuracy;
3. Separate a single frequency component from the complex frequency component.
Single-phase power filterHigher insertion loss, smaller leakage current
Can effectively suppress EMI noise interference between line and line, line and ground
Used in various electronic equipment and electronic measuring instruments. Single-phase power filters are used in small electronic equipment and electronic measuring instruments.
Category: With lead filter
Scope of application:
Suitable for all kinds of electronic and digital equipment
The main parameters:
Working voltage 250VAC
Frequency 50/60HZ
Temperature 25/085/25
Single-phase power filter function
Take the above picture as an example. This filter mainly filters out the interference electromagnetic waves contained in the electrical method. The input is live and neutral, and the output is also live and neutral, so each has two connectors.
The purpose of the power filter is to suppress electromagnetic noise, and the influence of noise can be divided into the following two types:
Emissions: To reduce the noise generated by the equipment that affects the power supply or other equipment below the allowable value of regulations (such as FCC part 15), such as the noise generated by switching power supplies.
Immunity (Immunity): It is to reduce the noise entering the equipment to the extent that it will not cause abnormal actions of the equipment, such as the equipment used in the transmitting equipment of the broadcasting station.
The noise to be suppressed by the power filter can be divided into the following two types:
Common mode: The same noise in two (or more) power lines can be regarded as the noise of the power line to the ground.
Differential mode: The noise between the power line and the power line.
The ability of the same power supply filter to suppress common mode noise and differential mode noise will be different. Generally, it will be explained by the frequency spectrum corresponding to the suppression amount (expressed in decibels).
The function of the power line filter is to enable the equipment to meet the requirements of the electromagnetic compatibility standard for conducted emission and conduction sensitivity. The power line filter is also very important for suppressing the strong radiation interference of the equipment.
Strictly speaking, the function of the power line filter is to prevent electromagnetic interference generated by the device itself from entering the power line, and at the same time to prevent the interference on the power line from entering the device. The power line filter is a low-pass filter, which allows DC or 50Hz working current to pass, but does not allow the higher frequency electromagnetic interference current to pass. The power line filter is two-way, it can prevent the interference on the power grid from entering the equipment to have an adverse effect on the equipment, so that the equipment meets the requirements of conduction sensitivity; it can also prevent the electromagnetic interference in the equipment from passing. The power cord is transmitted to the power grid to enable the equipment to meet the requirements of conducted emission. Power line filters must be used for equipment that can produce strong interference and equipment that is sensitive to external interference.
The equipment that can produce strong interference includes: equipment containing pulse circuits (microprocessors), equipment using switching power supplies, equipment using thyristors, frequency conversion speed control equipment, equipment containing motors, etc. Sensitive circuits such as: devices using microprocessors, small-signal analog circuits, etc.
Single-phase power filter applicationSemiconductor Industry
The third harmonic in most semiconductor industries is very serious, mainly due to the large number of single-phase rectifier equipment used in enterprises. The third harmonic is a zero-sequence harmonic, which has the characteristic of converging on the neutral line, which leads to excessive pressure on the neutral line and even sparking, which poses a great potential safety hazard in production.
Harmonics can also cause circuit breakers to trip and delay production time. The third harmonic forms a circulating current in the transformer, which accelerates the aging of the transformer. Severe harmonic pollution will inevitably affect the efficiency and life of the equipment in the power distribution system.
Chemical fiber industry
In order to greatly increase the melting rate, improve the melting quality of glass, extend the life of the furnace, and save energy, electric flux heating equipment is commonly used in the chemical fiber industry, and the electricity is directly sent to the fuel-heated glass tank with the help of electrodes. These devices will generate a lot of harmonics, and the spectrum and amplitude of the three-phase harmonics are quite different.
Speech processing
This is the end of the introduction of the single-phase power filter. If there are any deficiencies, please correct me.
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