4_IPS OM Manual Excerpt.pdf

1 THEORY OF OPERATION

The Influent Pumps operate in a Lead/Lag with Time Delay Start/Stop sequence.

The Pumps speed is controlled by a Level PID controller with redundant Level Transmitters. The PID controller output controls the speed of all Pumps that are running. The PID controller Gain and Integral values change based on the number of Pumps running. The moment that 2 or more Pumps are ON, the Pumps Speed will be changed to the preset value for 2 Pumps. When 3 or more Pumps come ON, the Speed will be changed to the preset value for 3 Pumps. Once the Speed has been changed to the preset value, the PID will modulate the Pumps Speed based on the Wet Well Level. All Pumps are interlocked with the Influent Wet Well High Gas Level detector and will shut off all pumps that are running. When the Wet Well Low-Low Level is detected the Lead Pump will shut off. In Automatic mode, when a pump is called to run and it is not available, then the next available pump in the sequence will take its place. If the current Lead or Lag pump fails, then the next available pump will be called to start after a time delay.

1.1 Lead Pump

The Lead Pump always operate based on the Influent Wet Well Level.

The Pump starts when the Level is above the Start Lead setpoint and stops when the Level is below the Stop Lead setpoint.

1.2 Lag Pumps Start Sequence

When the PID’s output is above the START NEXT setpoint, the next available Pump is requested to start. A Start Delay Timer is initiated and starts the Pump when it is done timing. The PID’s output changes to a preset Gain, Integral and Output so that all Pumps running ramp up or down together based on Wet Well Level. If the PID’s output is above the START NEXT setpoint again, the next available Pump will be requested to start. Below summarizes the Lag Pumps Start Sequence.

1. Lag Small Pump ON

2. Lead Large Pump ON and Lag Small Pump OFF

3. Lag Small Pump RESTARTS

4. Lag1 Large Pump ON

5. Lag2 Large Pump ON

Note: Lead Small is always on.

1.3 Lag Pumps Stop Sequence

Assuming the current conditions has all five Pumps running then the moment the speed drops below the STOP LAST setpoint, the last pump ON is requested to stop. A Stop Delay Timer is initiated and stops the Pump when it is done timing. The PID’s output changes to a preset Gain, Integral and Output as the number of Pumps running changes. If the PID’s output is below the STOP LAST setpoint again, the next available Pump will be requested to stop. Below summarizes the Lag Pumps Stop Sequence.

1. Lag Small Pump OFF

2. Lag2 Large Pump OFF

3. Lag1 Large Pump OFF

4. Lead Large Pump OFF and Lag Small Pump RESTART

5. Lag Small Pump OFF

2 CONTROLS DESCRIPTION

2.1 Influent Pumps Screen

Alarm Indicators Area

Start/Stop Delay Timer

Setpoint/Indicators

Influent Pumps Control Panel

Wet Well Level Indicator

Pumps Speed Indicator

Influent Pumps Status

Wet Well Alarms

Influent Pumps Controls Status

Influent Flow, Daily Flow

Totalizer and Max Flow Limit

Influent Sampler

Diversion Sampler

2.2 Alarms Indicators

When any Alarm as indicated in the Alarms area, is true, the background of that Alarm will blink RED.

Gas Detected

A High Gas level is detected in the Wet Well. All Influent Pumps will be shut off.

Pump Shut Down

This alarm will occur when a High Gas level is detected.

Wet Well High Level This alarm will occur when a Wet Well level is above the setpoint.

Wet Well Low Level

A Low Low Wet Well level will shut down the Lead Influent Pump.

Sampler Fail

The Influent Sampler has failed.

Sump Pump High Level

A High Level in the Sump Pump Well is detected.

2.3 IPS Control Panel

Changed Text of button - Inf. Pumps Step/Seq. to Influent Trend - done

The Control Panel holds all the control setpoints for the automatic operation of the Influent Pumps. Clicking any of the buttons will bring out the corresponding popup window as described below.

2.4 Influent Pump Lead/Lag Selector

The Pump Lead/Lag Selector popup provides controls for selecting which pump is lead and which is lag. A RED light indicates the selected sequence.

1 – 5

Pump 1 is lead and Pump 5 is lag.

5 – 1 Pump 5 is lead and Pump 1 is lag.

2-3-4 Pump 2 is lead, Pump 3 is lag1 and Pump 4 is lag2.

3-4-2 Pump 3 is lead, Pump 4 is lag1 and Pump 2 is lag2.

4-2-3 Pump 4 is lead, Pump 2 is lag1 and Pump 3 is lag2.

2.5 Manual Start Next/Stop Last

(Not sure if this function is working)

This popup provides a method to manually start or stop the next pump in the sequence. If the START NEXT button is selected, the next pump in the sequence will be started. If the STOP LAST button is selected, the last pump in the sequence will be stopped.

% Speed Start Next/Stop Last

This popup provides a data entry point for entering the Start Next and Stop Last setpoint.

Start Next

When the PID output, hence the Pumps speed, is above the Start Next setpoint, the next available pump is requested to start.

Stop Last When the PID output is below the Stop Last setpoint, the last pump started is requested to stop.

2.6 Influent Wet Well Alarm

This popup provides data entry for the Wet Well Level Alarms Low-Low and High-High. It also, provides data entry for the Lead Pump Start and Lead Pump Stop setpoints. The setpoints unit are in feet. The above numbers indicate the Lead Pump will start at 6 feet and will stop at 4 feet.

The Low-Low Alarm will shutdown the Lead Pump.

2.7 LEL Influent Pumps Shutdown

The Time Delay Shutdown function is not implement however, the Low- Low Level Alarm will shut down all Pumps without delay.

2.8 Influent Trending

Changed Text of button - Inf. Pumps Step/Seq. to Influent Trend - done This popup provides Influent Flow Trending data.

2.9 Loop Tuning

Clicking on the Loop Tuning button will bring out the Loop Tuning/Controlling screen. On the PID graph, the correct information begins to display from the right hand side. If no other popup window is opened after closing the PID popup, then the PID graph will continue to display correct information.

Auto

Sets the PID Controller for automatic operation.

Manual Sets the PID Controller for manual operation.

PV – Process Variable

The current Wet Well Level value.

SP - Setpoint

Sets the PID Controller to maintain the Wet Well Level at this Setpoint value when in Auto.

Output The PID Output is the speed of the pumps when they are operating in automatic. It is the speed the pumps run at to get to or to maintain the Wet Well Level at the Setpoint value. If the PID is in Manual, the Operator can manually control the pumps speed by entering a value from 0 to 100 here.

Gain A value entered to control the PID reaction to a change in the Wet Well Level. The higher the value, the faster the PID response.

Typical value for Gain is 0.003. See Dynamic Tuning for more information.

Integral As the number of pumps change, the PLC will write once, the Integral to the Output. See Dynamic Tuning for more information.

2.10 Dynamic Tuning

Text has been changed:

2 Sm. Pumps 14.8 MGD 1 Lg. and 1 Sm. Pump 25.4 MGD 2 Lg. and 1 Sm. Pump 43.4 MGD 3 Lg. and 1 Sm. Pump 61.4 MGD

(need to be verified)

The PLC changes the Gain and Integral values based on the number of pumps running. The objective of the Dynamic Tuning is to provide a gradual increase or decrease in pumps capacity as more pumps are starting and stopping. The Integral value applies as a one-shot based on the number of pumps running while the Gain value applies to the PID continuously. Example: Assume that a small pump is running and then a large pump comes on. The PLC will write once to the PID’s Integral a value of 75. The PID’s Output value is now 75% Speed for all pumps running. The PID then modulates the Output based on the PV and SP values.

2.11 Wet Well Level and Alarms

The current Wet Well Level is display here. The Operator can enter the Alarm Setpoints by clicking on the corresponding box and enter the value.

When the level is at the Alarm Setpoint, the background will blink RED.

2.12 Pump Controls Status

The Pump Controls Status provides the current operating mode of the pump. Clicking on the Pump object will reveal the Pump’s Start/Stop and Speed Control popup window.

REMOTE

The HOR switch is in Remote. The pump is receiving its controls from the PLC/HMI.

AVAIL

The pump is available for automatic operation, when the pump’s controls are in Remote, Pump Mode Control is in Auto, Enabled and not Failed and Manual Speed Control is also in Auto.

AUTO

The pump is in Automatic. The pump Start/Stop is controlled by the PLC.

MAN

The pump is in Manual. The pump Start/Stop and Manual Speed Control is controlled by the Operator through the popup window.

DISABLED

The pumps Disabled from operation is represented by a red circle with a slash.

Pump Object RED - The pump is running.

GREEN - The pump is off.

Blinking GREEN -The pump has failed.

% SPEED

The current pump speed. The speed is controlled by the PID Controller when in Auto.

2.13 Pump Controls Popup

The Influent Pumps popup window provides the controls for controlling the pump’s start/stop and speed. The Pump can be started manually by clicking on the MAN button and then click on the START button. The Pump’s speed can also be controlled manually by clicking on the MAN button under the Pump Speed Control box and enter the desire speed in the Manual Speed Input box.

Pump Mode Controls

Sets pump for automatic controls.

Sets pump for manual controls.

START

Starts the pump when in manual mode.

STOP

Stops the pump when in manual mode.

DISABLE

Renders the pump inoperable.

RESET

Resets failed pump.

Pump Speed Controls

Sets the pump to receive its speed from the Wet Well Level PID Controller.

Sets the pump to receive its speed from the Manual Speed Input box.

Pump Status

See Pump Controls Status for more information.

2.14 Influent Flow

Displays the calculated Influent Flow, Daily accumulated Flow and Sets the plant Influent Flow Limit.

3 STARTUP PROCEDURE

1. Set the Start/Stop Time Delays.

a. LEAD 60

b. 1LAG 180

c. 2LAG 180

d. 3LAG 180

e. 4LAG 180

2. Set the Max Flow Limit: 50 MGD

3. Set the Pump Lead/Lag Sequence.

a. 1Lead/5Lag or 5Lead/1Lag

b. 2-3-4 or 3-4-2 or 4-2-3

4. Set the Start Next/Stop Last Speed.

a. Start Next 90

b. Stop Last 50

5. Set the Influent Wet Well Alarms.

a. High-High Alarm 15

b. Start Lead 6

c. Stop Lead 4

d. Low-Low Alarm 3

6. Set the Pumps Controls and Speed Controls to Auto.

a. Pump 1

b. Pump 2

c. Pump 3

d. Pump 4

e. Pump 5

7. Enter the Setpoints for the PID’s Gain and Integral.

a. 2 Sm. Pumps 14.8 MGD Gain = 0.003 Integral = 70

b. 1 Lg. and 1 Sm. Pump 25.4 MGD Gain = 0.003 Integral = 75

c. 2 Lg. and 1 Sm. Pump 43.4 MGD Gain = 0.004 Integral = 80

d. 3 Lg. and 1 Sm. Pump 61.4 MGD Gain = 0.004 Integral = 80

8. Enter the Setpoint for the PID and set it to Auto.

a. SP = 7.5

b. Click on the Auto button.

Note: All operator inputs are adjustable and may not be the current values.

3 STARTUP PROCEDURE