Feedthrough Filters

The easiest way of preventing EMI is to enclose the electrical equipment (if possible) in a metal case. This is popularly known as 'Faraday Cage' and is good at minimizing Radiated Interference (RMI). Additionally, most electrical and electronic systems need a sequence of Inductor-Capacitor (LC) filters to remove EMI. These filters are called as Feed-through (FT) capacitors and FT filters.

FEEDTHROUGH FILTERS: A feed-through device consisting of an inductor positioned between two capacitors connected to the ground. L, T, LL and Pi are different types of feed-through filters.

Performance characteristics:

  • Provides filtering in high frequency ranges (> 1 GHz)
  • Can provide EMI protection in standard, high and extended performance ranges
  • 10 – 300 A, 130 V DC / 250 V AC
  • FT capacitor performance increases with higher frequency, thus providing better cost benefit
  • FT filters can be used when higher performance is required over broad range of frequencies
  • FT filters have better performance than FT capacitors when the noise source impedance is less than 50 Ohms

Applications of FT Filters:

  • Home appliances
  • Telecom Systems - Base Station Racks, Routers, Broadband Communications
  • Medical Systems - MRI Rooms, Screened rooms
  • Power Systems - Main Power Supplies, Power Amplifiers and generators, high current SMPS
  • Industrial Systems - High Frequency welding equipment, Rolling Mills, Variable Speed Drives, Frequency converters, Electric drives. Industrial controls
  • Military Systems - Military vehicles and equipment
  • Office Automation
  • Non-Conventional Energy


  • EMIS feed-through components support a wide range of current ratings, capacitance, thread sizes and mounting options
  • Components are compact in size, have high contact reliability and are easy to install
  • EMIS filters are available in voltage ratings of 110/230/440/520/680 VAC & with current rating up to 2500Amps
  • EMIS developed Military grade Chamber filters with >80dB suppression from 14KHz to 30GHz. Filters rated for 400Hz AC applications are also covered in this range. These products are under safety certification.
  • EMIS filters have International Safety Certification as per CSA/C-US /NEMKO. EMIS is the only brand manufactured in India with this Certification.
  • EMIS is associated with Indian Military R&D in developing and certifying HEMP filters rated up to 1500amps in 3ph AC as per MIL 188-125.
  • EMIS has developed Power line feed through Capacitors & feed through filters Up to 600 Amps for 250V AC application. These are approved by both Indian & international customers and are available as filter plates. These products are under safety certification.
  • Custom built feed-through components are available at customer request.
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  • Voltage Range

    440 VAC

  • Current Range


  • Application

    Telecom Systems