What is loop checking ?
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Answer Posted / dnz_72
In simple terms it is a test starting at the process variable through the controller and back to the control device to see if everything is working properly.
As as example: You have a tank with a water level controlled by an inlet valve that opens or closes as needed to maintain the level.
The signal from a level device (let's say a level transmitter) goes to a controller. A signal then goes from the controller to the level control valve opening or closing it. That is the control loop.
The loop test determines if the proper signal is going from the level transmitter to the controller and then is the correct signal going from the controller to the control valve and is it opening or closing as it should.
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