Single Phase Thyristor Triggering Card – LZF-10

Libratherm offers Single/Two-Phase Zero Cross Over SCR Firing Card Module LZF-10 for AC single phase/two-phase operated electrical resistive or inductive loads. This module is 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 the 180-degree phase angle of a single sinusoidal AC cycle, this leads to the generation of arcing on the contacts and may generate harmonics, which can cause an electromagnetic disturbance in the power lines and can also cause EMI to other electronic instruments on the panel. The Thyristor Triggering Card Module featured here eliminates the generation of voltage transients because of the zero cross over switching technique, also no arcing or audible noise will be observed during switching operation – since no mechanical contact movement is involved in the solid-state device.

This Burst firing Thyristor / SCR Control Card LZF-10 accepts a logic pulse of 12 to 36VDC from the temperature controller or from PLC and generates zero cross over single-phase gate cathode triggering pulses (G1K1+G2K2) for a pair of back to back connected SCRs.

Using LZF-10 module and external back to back connected SCR modules (such as Semikron make SKKT27, SKKT57, SKKT106, SKKT162, SKKT 273, SKKT 573) one can build solid-state relays rated for 25A to 500A @ 40 to 250VAC. We also offer RC snubber PCB for the SCR modules.