Heating element is in direct contact with the section of rail to be heated. Current is applied to the element which heats up and passes heat to the section of rail to which it is attached through thermal conduction
Heating element is not in direct contact with the rail section to be heated but is separated by a plastic tube or coating. AC is applied to the element which generates an alternating magnetic field which, through interference in the rail, induces heat inside the rail.
Capable of controlling heater activity based on ambient air temperature, rail temperature and local precipitation.