The PD Devices EMI Surge Protected Filters are designed to combat Electro-magnetic Interference, so lets explain what is Electro-magnetic Interference (EMI)?
Electro-magnetic Interference also called Radio-Frequency Interference (RFI) when in the radio frequency spectrum, it is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction.
The disturbance could degrade the performance of a circuit or even stop it from functioning completely. In the case of a data path, these effects can range from an increase in error rate to the total loss of all the data.
Both man-made and natural sources generate changing electrical currents and voltages that can cause EMI: ignition systems, cellular network of mobile phones, lightning, solar flares and auroras (northern / southern lights). EMI frequently affects AM radios, it can also affect mobile phones, FM radios and televisions, as well as observations for radio astronomy and atmospheric science.