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Thyristor Control- Using Logic Pulse

Hello,

We have requirement of 6 nos of single phase thyristor power controller in our heating application.

The control input to thyristor is logice pulse (3-32VDC) from PLC.

In PLC system there is only one PID control block and only one logic output which need to be connected to all 6 nos single phase thyrsitors.

My question is that is it possible to connect single logic output from PLC to 6 single phase thyristors individually so that all 6 thyristors can regulate the power as per control command from PLC.
Is it recommended or we need to have individual 6 logic outputs from 6 different PID blocks?

Please suggest.

Regards,
Sujit Jejurkar
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  • Bob Anderson (Technical Support Engineer) July 02, 2019 12:19
    Hello Sujit,

    It may be possible to connect to all 6 from one output just using one PID control block providing you do not want to control at different temperatures.
    So if you are happy they all turn on and off together that would be okay.

    However, the consideration is whether the output is capable of driving 6 units.
    Depending on your chosen SSR each input sinks current, this could be say 9mA or maybe higher, so with 6 that is at least 54mA and your PLC output must be capable of sorcing this current along with the pulsed output.
    Sometimes by placing the SSR's in a combination of parallel and series you can overcome such obsticles.

    Thought I mention it before you go ahead and order.
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  • Hello Bob,

    Thanks for your reply.

    There is only one process thermocouple input to the PID control block in PLC and corresponding to it one logic output.

    Can we use 2604 process controller with single thermocouple input and 6 individual PID controlled logic outputs (D1-D7) for respective 6 nos EPACK-Lite/1PH thyristors?

    Also please confirm the mA rating for the logic outputs (D1-D7) of 2604 controller.

    Can above will work successfully?
    Please advise.

    Regards,
    Sujit Jejurkar
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  • Hello Bob,

    Thanks for your reply.

    There is only one process thermocouple input to the PID control block in PLC and corresponding to it one logic output.

    Can we use 2604 process controller with single thermocouple input and 6 individual PID controlled logic outputs (D1-D7) for respective 6 nos EPACK-Lite/1PH thyristors?

    Also please confirm the mA rating for the logic outputs (D1-D7) of 2604 controller.

    Can above will work successfully?
    Please advise.

    Regards,
    Sujit Jejurkar
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  • Jon (Official Rep) July 09, 2019 11:16
    Hello Sujit,
    Yes, you can use the Standard digital outputs(D1 to D7) to drive the Epacks - These are open collector o/p's so you will need an external power supply 10 to 35v, each O/P is current limited to 40mA.
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