Single/Two Phase Thyristor Triggering Card – LTC-13

Libratherm offers SCR Firing / Thyristor Triggering Card LTC-13, which is designed to fire or trigger back to back connected SCRs or SCR/Diodes using synchronized phase angle control technique. This card accepts analog control signals of (0-5)/(0-10)VDC or (4-20)mA and provides proportional gate/cathode triggering pulses G1K1 + G2K2. These pulses can be used to trigger back-to-back connected SCRs up to 1000Amps with gate current up to 300mA. This card also provides a built-in regulated 5VDC supply to connect an external potentiometer to manually control the SCR Firing. The on-card ramp up and ramp down settings allows a gradual rise and fall of the voltage levels across the load.

Many times it is required to limit the current flowing through the load. Such a current limiting feature is available in LTC-13 – for single-phase, two-phase load, and three-phase. The load current or Line current feedback is derived from the external CTs. This feature is useful for transformer load or inductive loads or for heating elements like Silicon Carbide and Molybdenum Disilicide, which exhibits a significant change of resistance with an increase in temperature. This feature will restrict the maximum load current to the value set using the on card current limit (CL) potentiometer. On the sudden increase in the current, the current trip feature will over-ride the current limit feature and the firing of the thyristor will stop instantly. The trip contacts are available on the terminals.

This Thyristor Firing Card Module is designed for heating control applications to control the single-phase, two-phase, and three-phase AC power across the heating coils to control the star or delta connected transformer loads.

This Phase Angle SCR Triggering Card Module can also be used for half-wave, full-wave, or bridge rectifiers using SCR-DIODE or SCR-SCR Bridge, where the rectified DC output can be gradually varied to the desired level using the control signal or the potentiometer.