RADIO INTERFERENCE SUPPRESSION 1. Origin and Spreading of Interference: There are two main sources of radio interference: • Devices, which due to their construction produce RF energy. These include generators for use in industry, medicine and science, as well as oscillators, radio and TV receivers etc.
Can radio interference suppression capacitors be used in a mains application?
Before radio interference suppression capacitors can be used in a mains application, they must fulfil safety standards defined by national authorities. The basic world standard for these components is the IEC 60384-14 (ed.3).
The suppression capacitor is the most effective interference component. Its impedance decreases with the frequency, so that we have a short circuit between the mains terminals and/or between the terminals and ground at high frequency. Capacitors for applications between the mains terminals are called:
EMI suppression capacitors, as the name implies, are used to reduce electromagnetic interfer-ence. They are connected directly to line and are therefore exposed to overvoltages and tran-sients, which could damage the capacitors. For this reason, EMI suppression capacitors must comply with the requirements of the following safety standards:
Which X-capacitor is used for radio interference suppression?
Figure a) shows the radio interference suppression of the motor of a piece of electrical equipment (vacuum cleaner, portable drill, etc.) of protection class I. Capacitor Cx, which is used for reducing the symmetrical interference voltage, is located between the conductors of the mains and is therefore an X-capacitor.
Are X and Y capacitors effective against electromagnetic interference?
Depending on how they are connected, X and Y capacitors are effective against different kinds of electromagnetic interference. X capacitors connected between the line phases are effective against symmetrical interference (differential mode).
Can safety capacitors be used in a DC/DC converter?
More recently, capacitively-coupled DC/DC converter designs have appeared that use safety capacitors to provide input-to-output isolation. And safety MLCCs are finding use in antenna coupling applications. Since capacitors in EMI filters are connected to ac power lines, these capacitors can fail due to over-voltages and transients.