After commissioning, the displayed level tracks the scheduled setpoint, the pump accelerates when the tank is low, and the drive enters a stopped or sleep state only after the upper condition is stable. Build that result one signal at a time: displayed value, sensor scaling, controller action, speed command, and run state.
What Is the Screen Telling You?
Start with the operator-visible values. A level that looks correct does not prove that the drive is using it. The displayed tag may be bound to the right sensor while the PChV1 PID block reads a different input. The tag is right; the binding is wrong.
| Displayed item | What it must represent | Failure indication |
|---|---|---|
| Process value | Scaled tank level or a pressure value proven to represent hydrostatic head | The value does not follow an independently measured level |
| Setpoint | The level required by the operating graph | The graph changes, but the controller setpoint remains fixed |
| Controller output | The PChV1 frequency or speed demand | Level error changes while output remains unchanged |
| Run state | Run, stopped, sleeping, or inhibited | A valid speed demand exists while a permissive blocks the pump |
Trace each item backward from the display to its tag, driver channel, controller register, and physical input. Watch raw and scaled values together while the level changes. If a scheduled value comes from another controller, confirm that the driver updates it and that the PID block references the same address.
Commissioning check: change the active setpoint by a small, safe amount and confirm that the displayed setpoint, controller error, and frequency demand respond in that order.
Does the Pressure Signal Really Represent Level?
A pressure sensor measures level only when its pressure changes predictably with liquid head. For a constant-density liquid, the relationship is h = P / (rho × g), where h is liquid height, P is hydrostatic pressure, rho is density, and g is gravitational acceleration. Scale the signal from known empty and full reference points rather than assuming that pressure units equal level units.
Sensor location decides whether this conversion works. A sensor connected to the tank bottom can measure static head. A sensor on the pump discharge may also see velocity, pipe loss, check-valve state, and pump pressure; that signal can change with motor speed even when tank level barely moves. In a closed tank, gas-space pressure also contributes to the reading unless the measurement removes that component.
- Place the tank at a known low level and record the raw input.
- Place it at a known high level and record the raw input.
- Enter those points in the input scaling used by the controller.
- Compare the displayed result with an independent level measurement at one intermediate point.
Configure sensor fault handling so an open circuit, short circuit, or out-of-range value cannot command unrestricted filling. Choose the safe pump response from the process risk assessment.
Commissioning check: at two stable tank levels, verify that the raw input and scaled level move monotonically in the correct direction and remain stable while pump speed is held constant.
Should PChV1 Use PID or Two-Position Control?
Both configurations can operate a filling pump, but they solve different control objectives. Select the method from the required level graph, not from the hardware already wired.
| Required behavior | Control method | Effect |
|---|---|---|
| Hold level near a continuously changing setpoint | PChV1 PID control | Modulates pump frequency as level error changes |
| Fill below a low threshold and stop above a high threshold | Two-position control with hysteresis | Runs and stops the pump between defined limits |
| Frequent filling cycles with reduced mechanical and electrical shock | Drive-controlled start and stop | Uses configured acceleration and deceleration instead of direct switching |
For a filling pump, increasing speed normally raises the process value. Configure the controller direction so a level below setpoint increases its output. Reversed action drives the level farther from target: the pump slows when the tank is low and accelerates when it is high.
If the graph calls only for upper and lower limits, two-position control is simpler. Its equivalent action energizes filling below the low threshold and removes the command above the high threshold. Set enough hysteresis to prevent rapid cycling from sensor noise or surface movement. If the objective is close tracking, use PID and tune it against the tank's slow response; aggressive correction can produce long oscillations because accumulated volume continues changing after speed changes.
Commissioning check: simulate a process value below and above the setpoint. The output must rise when the tank is low and fall when it is high.
How Do You Connect the Sensor, PID, and Pump Command?
Configure one link at a time and use the installed PChV1 manual for terminal assignments and parameter identifiers. Those details vary by drive configuration and are not identified here.
| Setting | Location | Effect |
|---|---|---|
| Signal type and scaling | Analog-input configuration | Converts the sensor signal into engineering units |
| Feedback source | PID configuration | Connects the scaled level to the regulator |
| Setpoint source | PID or command configuration | Selects the schedule, local value, or external controller value |
| Frequency limits | Drive limits | Restricts pump operation to its permitted range |
| Acceleration and deceleration | Motor-control settings | Controls hydraulic and mechanical transients |
| Run permissive | Digital command logic | Prevents PID output from starting a blocked pump |
- Disable automatic operation and enter motor and pump limits from their nameplates and documentation.
- Wire and scale the pressure input, then verify its raw value before selecting it as feedback.
- Select the active setpoint source and verify that the scheduled value reaches the drive or supervising controller.
- Select the scaled signal as PID feedback and confirm the control direction.
- Configure initialization, filling, acceleration, and deceleration behavior for the hydraulic system.
- Test the pump in manual mode through its permitted speed range before enabling closed-loop control.
Commissioning check: in manual mode, command several allowed frequencies and confirm correct rotation, stable sensor readings, increasing fill rate, and no blocked run permissive.
How Should Sleep and Wake Operation Be Commissioned?
PChV1 sleep capability must be resolved against the manual for the installed unit. The configuration was described both as lacking a dedicated sleep mode and as having sleep-related settings in Appendix B. If Appendix B for the installed drive contains those settings, configure them there. If it does not, implement the state with available internal programmable logic or an external two-position controller.
A proposed arrangement used a sleep threshold of 49 Hz with almost no delay after maximum pressure. Treat 49 Hz as a proposed application value, not a universal setting. Measure the actual frequency, level, and flow at the full-tank condition. A sleep trigger must represent negligible filling demand or attainment of the upper level, not merely a frequency copied from another setup.
- Run the loop until the upper level condition is stable and record the frequency demand.
- Set the sleep condition from that measured operating state and add enough delay to reject acceleration, sloshing, and brief signal disturbances.
- Set wake from the required minimum level. If pressure is used, first prove that its scaled value represents that level.
- Coordinate wake logic with initialization and filling time so the controller does not interpret an empty line or delayed pressure rise as a failed response.
- Retest acceleration and deceleration after adding the state transitions.
Commissioning check: complete two fill-and-drawdown cycles without rapid restarting, false sleep entry, or failure to wake at the minimum level.
How Do You Verify the Complete Control Path?
Trend or record four signals together: setpoint, process value, frequency demand, and run state. Start below the lower target, pass through the control range, reach the upper condition, enter sleep or stop, then remove water until wake occurs.
| Observed symptom | Check next |
|---|---|
| Correct displayed level, wrong drive response | Feedback binding and PID action direction |
| Level changes when stopped | Sensor location, pressure reference, leakage, or external flow |
| Output saturates at a limit | Setpoint feasibility, scaling, pump capacity, and run permissives |
| Repeated sleep and wake | Hysteresis, delay, signal noise, and wake threshold separation |
| Schedule changes without controller response | Tag address, driver updates, and active setpoint source |
Commissioning check: verify the sequence low level → run → controlled filling → upper condition → sleep/stop → drawdown → wake, with every transition visible in the recorded signals.
FAQ
How do I choose between PID and on-off control for PChV1?
Use PID when pump speed must track a varying level setpoint. Use two-position control with hysteresis when the requirement is simply to start below a low limit and stop above a high limit.
How do I use a pressure sensor as a tank-level signal?
Record the raw signal at known low and high levels, scale those points into level units, and check an intermediate point. Mounting must measure static liquid head rather than pump discharge pressure.
How do I configure PChV1 sleep mode?
Check Appendix B of the manual for the installed drive. Where sleep parameters are absent, build the state with available programmable logic or an external controller; validate any proposed 49 Hz threshold against measured full-tank operation.
How do I prove the PChV1 level-control loop is working?
Record setpoint, level feedback, frequency demand, and run state through a full cycle. The final verification is low level → run → controlled filling → upper condition → sleep/stop → drawdown → wake.