Modify existing PLC Program
Budget: £20 – £250 GBP
Using RS Logix 5000 v13
The Site A Flow Control Valve will be controlled by the Supply A Control System using FIT01001 to control to Flow Control Valve Setpoint [F11].
The Site A Flow Control Valve Setpoint [F11] shall be theved using this following calculation:
( ( Site A Level Derived Flow Setpoint + Site B Flow Request ) + [FITXXXX2] ) - Site B Flow Request - Site C Flow Request
The new Site A Control Valve will ensure that priority is given to supplying Site A. Site B is second priority and is only granted water if it is available.
Due to output constraints of the RGF plant, only two flow requests can be fulfilled at any one time. With Site A being priority, the new total flow setpoint will be either of the two summations:
• Site A level-derived flow setpoint + Site B requested flow
• Site A level-derived flow setpoint + Site C level-derived requested flow
As Site B is second priority, controls shall be put in place to ensure Site B gets water when it requests. This will mean that the supply to Site C will be stopped if they are both requesting supply at the same time.
If water is being requested from Supply B by Site A, thereby increasing site outflow, there is a possibility to supply all three sites. If Site A and Site B flow setpoints are being met, then flow will be directed to Site C to meet the flow setpoint. Any excess flow after all three sites flow-setpoints have been met will be directed to Site A.
This control will be performed by an external controller which will be monitored at the PLC. The control from the external controller will be as follows.
If the Flow setpoint is 0l/s the Valve will be called to close (Should be the case on a High Level at Site A)
Provided the Flow setpoint is greater than 0l/s the Valve will be controlled by a PID block to achieve the required flow (As measured at the new Site A Line Flowmeter)
In the event of the new Flowmeter being faulted the Flow Control Valve will be driven fully open. The valve will be considered faulted if the watchdog pulse fails.
The external controller will receive a Flow setpoint from the PLC, while the Valve Position will be monitored.
The Site A Flow Control Valve will be controlled by the Supply A Control System using FIT01001 to control to Flow Control Valve Setpoint [F11].
The Site A Flow Control Valve Setpoint [F11] shall be theved using this following calculation:
( ( Site A Level Derived Flow Setpoint + Site B Flow Request ) + [FITXXXX2] ) - Site B Flow Request - Site C Flow Request
The new Site A Control Valve will ensure that priority is given to supplying Site A. Site B is second priority and is only granted water if it is available.
Due to output constraints of the RGF plant, only two flow requests can be fulfilled at any one time. With Site A being priority, the new total flow setpoint will be either of the two summations:
• Site A level-derived flow setpoint + Site B requested flow
• Site A level-derived flow setpoint + Site C level-derived requested flow
As Site B is second priority, controls shall be put in place to ensure Site B gets water when it requests. This will mean that the supply to Site C will be stopped if they are both requesting supply at the same time.
If water is being requested from Supply B by Site A, thereby increasing site outflow, there is a possibility to supply all three sites. If Site A and Site B flow setpoints are being met, then flow will be directed to Site C to meet the flow setpoint. Any excess flow after all three sites flow-setpoints have been met will be directed to Site A.
This control will be performed by an external controller which will be monitored at the PLC. The control from the external controller will be as follows.
If the Flow setpoint is 0l/s the Valve will be called to close (Should be the case on a High Level at Site A)
Provided the Flow setpoint is greater than 0l/s the Valve will be controlled by a PID block to achieve the required flow (As measured at the new Site A Line Flowmeter)
In the event of the new Flowmeter being faulted the Flow Control Valve will be driven fully open. The valve will be considered faulted if the watchdog pulse fails.
The external controller will receive a Flow setpoint from the PLC, while the Valve Position will be monitored.