Hi there,

We are a manufacturer of an ultrasonic imaging system, now we are performing CS(conductive susceptibility) test but failed till now.
The test is to couple a 150k~80MHz noise into AC power of the system under test, and because we use ultrasonic signal among 20~50MHz to form the ultrasonic image, the image is highly distorted by the CS noise around 20~50MHz.
We've asked a few of EMI filter manufacturers for help, however, all of them confirmed that they only design EMI filters for CE(conductive emission) test, no product for CS test, the main differences between CE and CS test are :

• CE(conductive emission) : prevent conductive emission from the system under test to other systems, test frequncy : 150Khz~30MHz
• CS(conductive susceptibility) : test the noise susceptibility from other system to the system under test, noise is coupled from AC power input, frequency range from 150Khz~80MHz

Basically a AC power filter to filter out 20~50MHz noise may work, but we cannot find a suitable part from the market.
Any comments ? Thanks a lot !!!

--- Below is part of the CS(EN61000-4-6) regulation for reference ---

CS(Conducted Susceptibility) :

 Regulation : IEC 61000-4-6 Immunity to conducted disturbances, induced by radio-frequency fields

 Test method :
 This test shall be performed on the AC mains power port (if any) of radio equipment and associated ancillary.
 The test level shall be severity level 2 as given in IEC 61000-4-6 corresponding to 3V rms unmodulated. The test signal shall
then be amplitude modulated to a depth of 80% by a sinusoidal audio signal of 1000Hz
 Frequency range from 150 kHz to 80 MHz with the exception of the exclusion band for transmitters, receivers and duplex
transceivers (see clause 4).

 

Hi Shengwuei,
Have you solved this problem?
Because I have a similar case, and also cannot find a solution.
Thanks!

 

If you can determine what input level of interfering signal over the frequency range you can tolerate then from that you can calculate the filter attenuation value you will need to meet the requirement. Then you can buy a power line filter that meets this required attenuation value. Since filters are generally bi-directional you should be able to use an appropriate filter designed to reduce conductive emission. If they are a directional type then you can connect it in reverse.

Google "military power line filters" to find several suppliers of such filters.

If you can't find a standard filter to do the job then you may need to have a filter company design a custom unit.