How to control electric heating with CS3000
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This post was last edited by jl1502 on 2016-5-14 at 14:20. How is electric heating control implemented in the Yokogawa CS3000? What hardware is required, and which function block is used for control? Solid-state relays are used in the heating circuit, mainly to enable stable control at a specific temperature.
I don’t quite understand; I might not be able to help you :)
Electric heating is generally controlled by the electrical system; a 220V supply is provided. There is an on-site control panel where temperature alarm settings can be configured
Controlling electric heating mainly involves controlling thyristors; there are both current signals and voltage signals, and a PID function block is required, similar to controlling control valves
This post was last edited by normalboy on 2016-5-14 at 19:46. Electric heaters in hoisting equipment generally work in this way: the control center can also control the electric heater via this local panel from a distance, and receive feedback on any faults associated with that local panel; these signals are usually dry contact signals, of the DI/DO type. If there is also a remote heating temperature setting signal, an AO might be required as well. Normally, these functions are implemented by the on-site controller itself.
If I want to implement this in DCS now? I have an electric heating system here; currently, there is no controller on site – everything is connected to the DCS. I’m not sure how to control it
Electric heating equipment comes with a thermostat; the temperature of the heating rod is fed back to the thermostat, and thyristor-controlled power is supplied to the heating rod, thus forming a power control circuit for electric heating. How is the power of electric heating maintained using the 4-20mA signal from the DCS? As for the control loop of the DCS, the temperature to be monitored should be the temperature of the \"heated\" medium; the output of this TIC is sent to the temperature controller as the setpoint.
Can a DCS generate pulse signals to keep the solid-state relay in a continuous on/off state, thereby maintaining the temperature? If there is one, which functional block is it?
I haven’t tried this, but I think it’s a bit difficult. The tradition is as follows: Suppose you use a heating element to heat the air; then the temperature of the air at the outlet is the parameter you need to control, while the temperature of the heating element itself is essential for maintaining that air temperature (for example, if the heating element maintains a temperature of 600 degrees, then the air temperature will be around 200 degrees). Therefore, the temperature control of the heating rod is achieved using a thermostat, whose continuous output is used to adjust the power of the thyristor (a linear power relationship can be assumed). The temperature of the air, TIC, can be controlled via the DCS, and it can be considered as a cascade loop: air TIC -- cascade -- heating element TIC (thermostat); the temperature of the heating element is controlled first. When power is modulated using the on/off operation of solid-state relays, the air temperature lags behind (based on my personal understanding)