Libratherm offers single phase zero cross over SCR firing cards for AC single phase operated electrical resistive or inductive loads. This card is basically developed to replace the electro-mechanical contactor with the solid state switch using silicon controlled rectifiers (SCRs). When the electrical load is operated through contactors – the AC cycle is switched ON or OFF at any point of 0 to 180 degree phase angle, this leads to generation of arcing on the contacts and may generate harmonics, which can cause electromagnetic disturbance in the power lines and can also cause malfunctioning of other electronic instruments on the panel. The card featured here eliminates generation of voltage transients because of zero cross over switching technique, also no arcing will be observed during switching operation – since no mechanical contact movement is involved in the solid state device.