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Manufacturers : Power supplies : Power filters

Noise is typically an unwanted factor that interferes with clean power supply. A noise generated in an electric power line by operation of a device connected to the electric power line sometimes adversely affects other devices connected to the same line, even when the line is not used for telecommunications. There are several types of radiation, wherein the common types are electromagnetic interference (EMI) and radio frequency interference (RFI). EMI is caused by the generation of radiation that is induced by the charge difference between three electrical wires from an AC power source, neutral line and ground line. EMI noise is classified into two common types. One is common-mode noise, wherein this is the radiation that is caused by the charge difference between live and neutral lines with respect to ground line, and normal mode noises generated between two conductive lines. Based upon the known phenomena of transient voltage surges and harmful electrical interference or noise, a variety of filter and surge suppression circuit configurations have been designed to filter EMI or RFI interference or suppress large transient voltages appearing on an electrical line. Power line filters consist of some number of capacitive and inductive elements arranged in a low-pass configuration, capable of passing the required supply current but providing attenuation of all unwanted frequencies and spike signals. An active power filter includes a feedback resistor and a shunt capacitor, an operational amplifier equivalent subcircuit, and a voltage drop source. An EMI filter is generally formed as an LC filter (a filter comprising inductors and capacitors) in which discrete elements such as a common mode choke coil, a normal mode choke coil, an X capacitor and a Y capacitor are used in combination. Power terminals which include power filters are typically located at the top of the cabinet to supply power to the various modules within the cabinet.

Listings on Power supplies : Power filters

  • BH Electronics
    Designs and manufactures custom and standard transformers, inductors, filters, baluns, chokes, assemblies and related devices. These products are intended for use in baseband, broadband and power applications from 20 KHz to 1 GHz. USA.
  • KR Electronics, Inc.
    Manufactures all filter types and individually synthesizes filters for special applications. Products include lowpass filters, bandpass filters, video and HDTV filters, highpass and notch filters, root cosine filters, diplexer filters, group delay networks, coils and transformers. USA.

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