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SCR Triggering Cards for Phase Angle Control

SCR Triggering Cards for Phase Angle Control

Product Specification :
Model wise descriptions :

Model Product Description Size (mm.)
LTC-12 SCR triggering card (single or two phase load) 115 x 115 x 70
LTC-13 SCR triggering card with Current Limit and
Current Trip feature (single or two phase load)
125 x 165 x 70
LTC-13D Same as LTC-13 but in DIN rail mounting frame 110 x 180 x 80
LTC-15 3 Phase SCR Triggering Card 
(for star and 6 wire delta load)
125 x 160 x 70


Products Discription

Libratherm offers SCR triggering cards model LTC-12, LTC-13 and LTC-15, which are designed to fire or trigger back to back connected SCRs using synchronized phase angle control technique. The card accepts analogue control signals of (0-5) 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 of as high as 500Amperes. The card also provides built in regulated 5VDC supply to connect external potentiometer to manually control the SCR firing. The on card ramp up and ramp down settings allows gradual rise and fall of the voltage output across the load.

LTC-12 and LTC-13 are same in all respect, except the card LTC-13 accepts the feed back signal from the external current transformer for the current limit and trip features. This feature is useful for transformer load or inductive loads or heating elements like Silicone Carbide and Molybdenum, which exhibits significant change of resistance with increase in temperature. This feature will restrict the maximum load current to the value set using the on card current limit (CL) potentiometer. On sudden increase in the current the current trip feature will over ride over the current trip feature and the firing of the thyristor will stop instantly. The trip contacts are available on the terminals.

These cards are designed to be used for heating control applications to control the single phase, two phase and three phase AC power to the heating coils or to the star or delta connected transformer loads.

These cards 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.

DATALOG16 software

• Can easily fire 15 Amps to 500 Amps SCR-SCR or SCR-DIODE modules.
• Single phase / 2 phase / 3 phase versions.
• Suitable for 4 wire star with neutral and open delta 6 wire configuration.
Suitable for single phase or three phase DC rectifiers.
• Auto / Manual operation.
• Accepts (4-20)mA / (0-5)VDC / (0-10)VDC control input.
• Soft start for smooth control.
• Adjustable power and current limit.
•Ideally suitable for resistive, transformer, inductive or heating loads like Silicone Carbide and Molybdenum which exhibits significant changes of resistance with increase in temperature.

Technical Specifications :

Available Configuration Single phase, Two phase, Three phase (4 wire star and  6 wire delta)
Control Action Phase angle control (self synchronized)
Control Signal (4-20)mA / (0-5)VDC / External potentiometer (any one)
Output Suitable Triggering Gate – Cathode pulses to fire back-to-back connected SCRs. 4 pulses (G1K1+ G2K2) for single or two phase control and 
12 pulses for 3 phase control.
Smooth Control Adjustable Ramp Up and Ramp Down Time for soft increase and decrease of output voltage
Current Control Current Limit and Current Trip settings using on card presets.
Feedback is taken from external CT (LTC-13 and LTC-13D)
Settings For adjusting maximum and minimum voltage per phase.
Load Type Suitable for both resistive and inductive loads
(15A to 500A @ 230/415 VAC)
Supply Voltage 230 / 380 / 415 VAC, 50/60 Hz. (As required)
Sizes  in mm. / Mounting 115 x 115 x 70 (LTC-12) – On Flat plate mountable using 4 screws.
125 x 165 x 70 (LTC-13) - On Flat plate mountable using 4 screws.
110 x 180 x 80 (LTC-13D) – 35 mm. DIN rail mountable.
125 x 160 x 70 (LTC-15) - On Flat plate mountable using 4 screws.