Technical Reference

This Technical Reference will provide you the keywords and definitions associated with power filters. This should help you develop more of an understanding of EMI filters and what features you should consider when specifying your power-line filter.

Interference Modes
Noise conducting out onto the power line in which the noise voltage is referenced between each line and earth.

Noise conducting out onto the input power line in which the noise voltage is referenced between the phases or phase and neutral, independent of earth.

Insertion Loss
Insertion loss is a general measure of a filter's performance. Measurements are made using 50ohm source and load impedance's in a static or unloaded condition. insertion loss is not an absolute measure of performance, but is used as a comparison tool or to define a general performance level.

Voltage Ratings
In general, single phase filters are rated for a max voltage of 250VAC at 50/60Hz and 480VAC for three phase filters. Radius Power uses capacitors which conform to the latest IEC 384-14 standard permitting operation above these values by 10% and operation to 400Hz up to 250V max.

Leakage Current
Current into the ground/earth of a system at the line frequency. Directly related to the capacitance to ground in the filter.
Lk = 2*(PI) *F *C *V
F= Line frequency
C= Capacitance
V= L-G voltage



Current Ratings
Defined at a given ambient temperature. Single phase filters are generally tested at 40°C and three phase at 50°C.


High voltage Testing
Two categories; type and production. Type testing is once for a duration of 60 seconds. 100% Production tests are

carried out for a duration of 1-2 seconds.


Climatic Ratings
Radius Power filters are designed for the following climatic classifications: 

25 = -25°C lower temp limit
100 = 100°C upper temp limit
21 = 21 days humidity


Component Ratings
Inductance: -30%/+50%
Capacitance.: +/-20%
Resistance: +/-10%

Ambient Temperature
Air temperature surrounding a device.

Filter Temperature Derating
Iamb = IR*(sqrt((100-TD)/(100-TR)))

IR = Rated Current

TD = Desired Ambient Temp

TR = Rated Ambient Temp


Breakdown Voltage
Level of voltage causing a break down of a dielectric (e.g. air) resulting in the flow of excessive leakage current.