Control for the booster pumping system is provided by RTU-800 located at the pump station with input from the PCS. The RTU will communicate with the MCC at the pump station to start and stop the pumps. In automatic (AUTO) mode, the pumps will start and stop based on water level in the Highland Reservoir.
RTU-800 controls the booster pumps based on a tank level signal and setpoints received from the PCS. The RTU will communicate with the MCC to start and stop the pumps and relay status and alarm signals to the PCS. An operator interface (OIT) will provide access to PCS functions and displays.
The MCC houses the VFDs for the pumps and will start and stop the pumps based on the signal received from RTU-800. The MCC has VFD keypads for manual control and display of VFD functions. The pump control valve solenoids are also be wired to the MCC and will coordinate pump starts and stop with operation of the valve. During normal operation, all signals are communicated to RTU-800 as required.
Local Control:
When the virtual HOA switch at the RTU-800 OIT is set to HAND, the pump will start immediately, accelerate at a rate set in the VFD, and run at the pump speed set at the PCS. The interlock with the pump control valve will cause the valve to open slowly after the pump starts. The valve may begin to open prior to complete VFD ramp up. Upon receiving a pump OFF signal, the interlock will keep the pump running while the valve slowly closes and allow it to stop when the valve is fully closed. The VFDs may ramp down to a preset minimum VFD speed prior to the valve being fully closed. The pump ramp down at the deceleration rate set at the VFD. The pump may be shut OFF by setting the virtual HOA to OFF. A HIGH pressure ALARM will stop a pump that is operating in HAND.
PLC Pressure Control:
The pressure control mode of operation was used during construction to maintain system pressure when Highlands Reservoir was offline. The general setup of pressure control mode includes allowing the VFDs to adjust to meet the setpoint pressure. The operators also need to open the altitude valve which allows flow to bleed off to the 7th Street Reservoir and circulate 150-250 gpm from the Highland main. Operators also need to add pressure blowoffs to select hydrants in the system to relieve pressure.
PLC Reservoir Control:
When the HOA is set to AUTO at the MCC, the pumps are controlled by RTU-800. The RTU will start the pumps when the Highland Reservoir level drops to the pump ON setpoint and will stop the pumps when the reservoir level has risen to the pump OFF setpoint. Interlock with the pump control valves are as described for HAND operation.
Only one pump is called at a time. If operators would like to run two pumps, they may turn on a second pump by hand and manually turn it off when pumping is complete. Operation setpoints may be adjusted during operation of the facility.
| Set Point (Tag) | Initial Summer Level | Initial Winter Level |
| Reservoir Low Low Level Alarm | 7 ft | 7 ft |
| Reservoir Low Level Alarm | 15 ft | 15 ft |
| Reservoir Pump ON level | 20 ft | 20 ft |
| Reservoir Pump OFF Level | 35 ft | 30 ft |
| Reservoir High Level Alarm | 35.5 ft | 30.5 ft |
| Reservoir High High Level Alarm | 36 ft | 31 ft |
| Discharge Pressure High Alarm | 112 psi | 110 psi |
| Discharge Pressure High High Alarm | 114 psi | 112 psi |
| Discharge Pressure Setpoint | 105 psi | 100 psi |
Pumps are alternated by RTU-800 with each pump start or after 24 hours. If the lead pump fails or AUTO is not selected, the standby 1 pump will become the lead pump and the standby 2 pump will move to standby 1 position. When an alarm is cleared and a pump is placed back in service, RTU-800 will allow it into the rotation again. The pump VFD speed will modulate to maintain the discharge pressure setpoint.
Excessive motor current or motor overload will cause the pump motors to be stopped immediately. These faults must be reset by pressing the virtual RESET button at the OIT. A VALVE CLOSED alarm will be generated at the PCS, if a pump runs for 10 seconds with the associated discharge valve.
PLC / HMI Configuration:
- Status Display:
- Pump HAND / OFF / AUTO (HOA) indication (each).
- Pump RUN / OFF status (each).
- Pump Speed (each).
- Pump station discharge flow indication.
- Pump station suction pressure indication.
- Pump station discharge pressure indication.
- Highland Reservoir level indication.
- Room Temperature indication.
- Generator RUN/FAIL status.
- Generator Low Battery status.
- Generator Low Fuel status.
- ATS Generator Position.
- ATS Utility Position.
- Operator Entries:
- Pump HOA virtual switch (each).
- Highland Reservoir level alarm setpoints (HIGH-HIGH, HIGH, LOW, LOW-LOW).
- Highland Reservoir level operational setpoints (Pumps ON/OFF).
- Pump station suction pressure alarm setpoints (HIGH-HIGH, HIGH, LOW, LOW-LOW).
- Pump station flow alarm setpoints (HIGH-HIGH, HIGH, LOW, LOW-LOW).
- Pump station discharge pressure alarm setpoints (HIGH-HIGH, HIGH, LOW, LOW-LOW).
- Building temperature alarm setpoints (HIGH, LOW).
- Minimum VFD frequency.
- Alarms:
- Pump FAIL (each).
- Highland Reservoir level ALARM (HIGH-HIGH, HIGH, LOW, LOW-LOW).
- Pump station suction pressure alarm (HIGH-HIGH, HIGH, LOW, LOW-LOW).
- Pump station discharge pressure ALARM (HIGH-HIGH, HIGH, LOW, LOW-LOW).
- Building Temperature ALARM (HIGH, LOW).
- Entry ALARM.
- Water on the floor ALARM.
- Generator FAULT.
- Generator Battery Low ALARM.
- Generator Fuel Low ALARM.
- Historical Trending:
- Booster pump room temperature.
- Highland Reservoir level.
- Pump station discharge flow.
- Pump station discharge pressure.
- Pump station suction pressure.