With new trends in furnaces and heating technologies, power electronics is playing important role in it. Gone are the days when we used contactor and two-point controller to control the temperature of furnace or oven. It is trend of thyristor or SCR controlled temperature control of furnace or oven.
Today, we shall see how it works.
The three phase resistive heaters can be of delta or star type. We can connect both types with SYCON kW controller. The heater is connected through SYCON KW controller to the power supply. In case of STAR connection, neutral is connected back to the SYCON KW controller. The control signal for SYCON KW controller is 4-20mA. At or below 4mA, the power output will be zero and at 20mA or above, the power output will be maximum i.e. 100%. From 4 to 20 mA, the power output will vary linearly from 0 to 100%.
A PLC is used to control the temperature. Temperature sensor is used to sense the temperature of furnace or oven. It gives feedback to the PLC which used PID (Proportional-Derivative-Integration) logic to control the temperature. It gives control output as 4-20mA signa;. This signal is given to SYCON KW Controller as input signal. According to this signal SYCON KW control adjust the power given to the resistive heater system. Thus temperature is controlled at very good accuracy.
Let us see how SYCON KW controller works. It senses the 4-20mA input signal. After that it computes the exact firing angle required. The firing angle is computed to match the power output asked via 4-20mA signal by the PLC or any PID controller used to control temperature of the oven or furnace. Exact zero crossing is detected and thyristors are fired at computed phase angle for all three phases. And we shall get desired power output at the resistive heaters.
SYCON KW controller can be used for any resistive heating element used in food, pharma or process industry. It can also be used in industrial ovens and furnaces where there are resistive heating elements. We can provide these controllers in any custom power (KW) value.
For more information, you may please contact us at info(at)sycon.co.in