Split range control system or Duplex Control
Split range controller has one input and two output.
Split control divides the controller output in to two distinct functions.
Heat/Cool controllers are one example of split control.
The controller senses the value of PV and SP at its input.A proportioning signal is generated in block A. The signal varies from 0 to 100% depending on the size and direction of the process error.
When PV is equal to SP and error is zero,the H/C signal is at 50%.
If the value of the PV decreases below SP,the H/C signal increases proportionally.
If the value of the PV increases above SP,the H/C signal decreases proportionally.