EMI/RFI Feedthrough Capacitors
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To introduce the EMI/RFI feedthrough capacitor series
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EMI/RFI Feedthrough Capacitors
- 1. EMI/RFI Feedthrough Capacitors Source: Tyco Electronics
- 14. Product Selection Tree Current Rating (10 - 300 Amps) Series Name Termination Style Filter or Capacitor Option 6 - Redundant Stud (AFC, DFC) 16 AFC 6 - CA (Refer to Individual Series)
- 15. Feedthrough Capacitors Selector Chart
Editor's Notes
- Welcome to the Tyco Electronics Corcom EMI/RFI Feedthrough Capacitors . This training module introduces the EMI/RFI feedthrough capacitor series.
- A filter is a combination of inductors and capacitors designed to take EMI/RFI noise off of the power line. EMI (Electro Magnetic Interference) is transmitted via radiation and by conduction over both power lines and signal lines. RFI (Radio Frequency Interference) is unwanted electro magnetic energy in the frequency range generally used for radio communications (150kHz - 30MHz). Filters remove two types of conducted electronic noise. Common mode noise which is the noise on both sides of the line (hot and neutral) in reference to ground and differential noise which is the noise between the two lines (hot and neutral).
- The power line cord going into any system can act as an antenna to bring EMI/RFI either into the system or out of the system, known as susceptibility and emissions respectively. A filter is typically located in a system right where the power cord comes into the piece of equipment, so the EMI/RFI will not affect the system or be emitted from the system back along the power line cord.
- Electronic equipment is susceptible to RFI noise problems as interference travels through the power line. It enters the equipment and can interfere with the logic within the equipment. Also, electronic equipment can cause emissions problems from RFI which is generated within the equipment and can exceed noise emission limits set by agency standards. This noise can then be conducted onto the power cord and out into the network, causing problems with other pieces of equipment.
- The major causes of EMI/RFI noise for emissions can be motors, switching power supplies, fans, digital circuits, relays, communications equipment, data transmission systems and other electronic noise created from components within a system.
- The emissions that come out of a piece of equipment are controlled by the FCC in North America and in Europe. The FCC has two classes, Class A which is industrial, commercial and light commercial, and Class B which is residential. CISPR/EN has both Class A and Class B under the same categorization.
- A filter is defined by many characteristics. One parameter is insertion loss. Insertion loss is the ratio of the signal voltage (in dB) without a filter, to the signal voltage with a filter in the same system. Insertion loss tables display the minimum insertion loss that can be expected utilizing these filters in a 50 ohm circuit throughout the frequency range.
- This insertion loss table depicts a series of parts that is available in 1, 3, 6, or 10A versions. For example, if you are using a 3A filter in a circuit and you have concerns about noise generated at 1 MHz frequency, you can expect a 36 dB reduction in the line-to-ground (or common mode) noise, and 14 dB reduction in noise on the line-to-line (or differential mode) noise at this frequency. You can help select the filter based on this insertion loss table by addressing the points of the scan that exceed the allowable threshold on the tables.
- The Corcom Feedthrough Filters and Capacitors are defined in the page. A Feedthrough Capacitor is a feedthrough terminal that provides a desired value of capacitance between the feedthrough conductor and the metal chassis or panel through which the conductor is passing. It is used chiefly for bypass purposes in ultra-high-frequency circuits. A Feedthrough Filter is a feedthrough device consisting of three elements -- an inductor positioned between two capacitors connected to ground. There are several styles of these filters (L, T, LL, Pi). We are offering Pi filters which are best suited for applications in which the input and output impedances are of similar value and high levels of attenuation are required.
- Feedthrough filters and capacitors offer a wide range of performance addressing AC and DC applications. The products are ideal for robust/corrosion resistant applications. They assure performance over specified temperature range. No soldering is required. The products meet EU directive and safety agencies’ requirements. The products offer a wide variety of off the shelf solutions (lower cost, shorter lead times). Custom solutions tailored to meet customer needs are also available.
- Two-terminal capacitors resonate with their lead inductance at 1-10MHz (depending on cap value) reducing their effectiveness at high frequencies. FT capacitors have no lead inductance due to the construction providing a much higher resonance frequency. FT capacitor performance (ideally) continues to increase with frequency. FT filters use FT capacitors so same benefit results. This graph compares the performance of a 1μF FT capacitor to a 1μF two-terminal capacitor.
- In high frequency applications, use feedthrough capacitors first (more cost effective). Use feedthrough filters when higher performance is needed through a broad range of frequencies. Filters perform better than capacitors when the noise source impedance is <50Ω.
- The part numbering system identifies each individual product in the Feedthrough line, indicating the current rating, series type, termination style, and filter or capacitor options.
- This Feedthrough Filter and Capacitor Selector Chart is a quick reference displaying the series within the product line, the current range, capacitor class, insertion loss data and the key benefit to each filter type. Use this selector chart to help determine which feedthrough filter or capacitor would meet your application needs.
- Feedthrough capacitors consist of a nickel plated brass metal case for good high frequency shielding, a tube wounded capacitor, molded insulator, sealing adhesive, and UL approved resin. These products are not required soldering for installation into a system to increase the reliability.
- Corcom feedthrough capacitors offer reliability and performance in high frequency applications. The use of the feedthrough capacitors are not limited in this highlight list.
- Feedthrough capacitors are designed for through-bulkhead mounting for offering high frequency filtering in line-to-ground applications. They should be mounted through a metal bulkhead or chassis. The bulkhead mounting surface should be clean and unpainted to offer a low impedance path from the capacitor or filter to the equipment chassis. Poor earth bonding will limit the available performance of the product and could compromise safety.
- Thank you for taking the time to view this presentation on “ EMI/RFI Feedthrough Capacitors ” . If you would like to learn more or go on to purchase some of these devices, you may either click on the part list link, or simply call our sales hotline. For more technical information you may either visit the Tyco Electronics site – link shown – or if you would prefer to speak to someone live, please call our hotline number, or even use our ‘live chat’ online facility.