This kind of heaters, MoSi2 Element ( Kanthal Super Elements TM* ), increase resistivity sharply with temperature. The value of the resistance at ambient temperature is very low and increase its value up to 10 times as a function of temperature. To don’t oversize in current the Thyristor unit it’s necessary to limit the current to the load reducing the voltage with phase angle firing and current limit. When the resistance value reach a setted value are possible two types of working method that can be selected from HMI:- Phase Angle plus current limit all the time long Or- Phase Angle plus current limit when the resistance is cold and transfering to Delayed Triggering if load is coupled with transformer. CD Automation can drive this kind of elements with REVO CL and Multidrive 1ph Units.