Why Use a Pressure Sensor with VFD?
In industrial and agricultural water supply systems, maintaining constant pressure is critical. A Variable Frequency Drive (VFD) paired with a pressure sensor creates a PID closed-loop control system that automatically adjusts motor speed based on real-time pressure feedback. This eliminates pressure fluctuations, reduces energy consumption, and extends pump lifespan.
This guide walks you through the complete wiring and parameter configuration process using the LAKINELE VFD300 N/T Series as an example.
What You Need
- VFD: LAKINELE VFD300 N/T Series (or any model with analog input and PID function)
- Pressure Sensor: 4-20mA or 0-10V output type (4-wire or 2-wire)
- Water Pump: Matched to your VFD power rating
- Wiring: Shielded signal cables recommended
Step 1: Wiring the Pressure Sensor to VFD
The pressure sensor connects to the VFD analog input terminals. Follow these steps:
- Red wire (signal positive) → Connect to the PC terminal on the VFD control board. This provides the 24V power supply to the sensor.
- Blue wire (signal output) → Connect to the AI2 terminal (Analog Input 2). This carries the pressure feedback signal (0-10V or 4-20mA) back to the VFD.
- Shield ground → Connect the cable shield to the VFD ground terminal (GND/E) to prevent electromagnetic interference.
Important: Use shielded cables for all analog signal wiring. Keep signal cables separate from power cables to avoid noise interference.
Step 2: Parameter Configuration
After wiring is complete, configure the VFD parameters for constant pressure water supply mode:
Set Function Mode (Parameter 29)
- Press the PRG key on the VFD keypad to enter programming mode
- Navigate down to Parameter 29 (Function Selection)
- Change the value to 06 — this selects the Constant Pressure Water Supply mode
- Press ENTER to confirm
Set Full-Scale Pressure (Parameter b0)
- Continue navigating to parameter b0
- Set the value to match your pressure sensor full scale — for example, enter 10 for a 10 kg (1.0 MPa) sensor
- Press ENTER to confirm
Set Target Pressure (Parameter b1)
- Navigate to parameter b1
- Enter your desired target pressure — for example, 5.0 means 5 kg (0.5 MPa)
- This value can be adjusted anytime based on your system requirements
- Press ENTER to confirm
Verify Settings
Return to the main display screen. You should see:
- Left side: Your target pressure setpoint (e.g., 5.0 kg)
- Right side: Real-time pressure feedback from the sensor
Step 3: Video Tutorial
Watch the step-by-step wiring and configuration video below:
How Does PID Constant Pressure Control Work?
The VFD uses a built-in PID controller to maintain constant water pressure:
- The pressure sensor continuously measures the actual pipe pressure
- The VFD compares actual pressure with the target setpoint
- If pressure drops below target → VFD increases motor speed → pump delivers more water
- If pressure exceeds target → VFD decreases motor speed → pump delivers less water
- This loop runs continuously, maintaining stable pressure regardless of demand changes
This is far more efficient than traditional on/off pressure switch control, which causes frequent starts/stops and energy waste.
Common Application Scenarios
- Building water supply: Constant pressure for residential and commercial buildings
- Agricultural irrigation: Stable water pressure for drip and sprinkler systems
- Solar water pumping: Combined with solar panels for off-grid water supply
- Industrial process water: Consistent pressure for manufacturing processes
- Boosting systems: Maintaining pressure in high-rise buildings
Why Choose LAKINELE VFD300 Series?
- Built-in PID function — No external controller needed
- Multiple input configurations: Single-phase 220V and Three-phase 380V models
- Power range: 0.75kW to 720kW
- Sensorless vector control — Precise torque and speed control
- RS485 Modbus communication — Easy integration with SCADA systems
- Comprehensive protection: Overcurrent, overvoltage, overheat, overload
Need Help with Your Project?
Our technical team can help you select the right VFD and configure the optimal setup for your application. Whether you need a single unit or bulk orders for distribution, we offer factory-direct pricing and full technical support.