Hey Everyone,
I am currently working on a project that has a heating element used in it and would like to vary the current that can go through it based on the power supply that we connect. In order to do this the most logical way seems that we could take the resistance measurement of the element while a master relay ensures the supply is disconnected; additionally, I'd like to know the element resistance for maintenance purposes. However, the point of contention is how to protect the measurement circuits from the high voltage that will manifest on the line when the relay is closed for regular operation. The current plan is to use a micro on the high voltage side, digitize the signal, and then optically transfer the value over an isolation boundary. The max voltage that the element will see is 240V from two 120V supplies 180degrees out of phase. Since the micro will be the only thing I need to power on the high voltage side (besides the element) and am isolating everything, I plan on using a capacitive dropper to power it and the measurement setup. I think I can remove most of the noise and get good accuracy down to my goal of .1ohm.
If you guys think I'm going about this in the completely wrong way just let me know! The design is still open to be modified.
Best Regards,
Mezz
I am currently working on a project that has a heating element used in it and would like to vary the current that can go through it based on the power supply that we connect. In order to do this the most logical way seems that we could take the resistance measurement of the element while a master relay ensures the supply is disconnected; additionally, I'd like to know the element resistance for maintenance purposes. However, the point of contention is how to protect the measurement circuits from the high voltage that will manifest on the line when the relay is closed for regular operation. The current plan is to use a micro on the high voltage side, digitize the signal, and then optically transfer the value over an isolation boundary. The max voltage that the element will see is 240V from two 120V supplies 180degrees out of phase. Since the micro will be the only thing I need to power on the high voltage side (besides the element) and am isolating everything, I plan on using a capacitive dropper to power it and the measurement setup. I think I can remove most of the noise and get good accuracy down to my goal of .1ohm.
If you guys think I'm going about this in the completely wrong way just let me know! The design is still open to be modified.
Best Regards,
Mezz