Taken from the DCC Supplies website for those who couldn't be bothered reading..
The popular Electrak 2 now has a fixed version, the Electrak 3.
This DCC Compatible track cleaner works just like the popular DC only high frequency cleaners, but is safe to use with DCC equipped locomotives.
We have tested this device with popular decoders, (including sound) without any problems!
The Electrak works by generating a high voltage, high frequency signal that is current limited to about 2 mA.
Due to the current limit, almost anything that is attached to the rails (e.g. a motor in DC or a decoder in DCC) will act as a short circuit to the Electrak. Thus, loads on the rails normally short the generated signal. Current flows from the generator, out one wheel set, across the rail load, into the other wheel set, and back to the generator.
Due to the low impedances involved, there is very little voltage in this loop (hence its safety and compatibility with DC and DCC). When the Electrak encounters a spot in the track that does not provide a good connection to the Electrak wheels (i.e. a dirty spot), the full 216 volts of the generator appears across this high impedance.
This high voltage acts to break up the contamination, and thus clean the track.
The Electrak is particularly good at destroying oxide films. Any exposed metal will form a surface oxide coat. Some of these metal oxides are insulators (such as brass) while some oxides do have conductive properties (such as ???nickel silver??? rails). Most metal oxides, however, do not conduct as well as the base metal. This is why abrasive pads work well. The abrasive action destroys the oxide coating allowing metal contact to the engine wheels. The dielectric withstanding voltage of thin oxide layers is on the order of 10-50 volts depending on the oxide and the oxide thickness. The Electrak has sufficient voltage to ???punch through??? the oxide (called defritting), destroying the oxide and exposing the base metal. The ability of the Electrak to remove track oxides is particularly handy if you have an outside layout or one exposed to high humidity.