How to Control a Frequency Converter with a Potentiometer in a Distribution Box

    Using a potentiometer to control a frequency converter in a distribution box mainly involves adjusting

 the output frequency of the converter via an analog voltage signal. Below are the detailed connection 

methods, parameter settings, and precautions:

 **1. Control Principle**  

The potentiometer divides the **10V reference voltage** provided by the frequency converter into a 

**0-10V analog voltage signal** by adjusting its resistance value. This signal is then input into the analog

 input terminal (AI) of the frequency converter to control its output frequency.

 **2. Wiring Steps**  

1. **Identify Frequency Converter Terminals**  

   Typical terminals on a frequency converter (using common labels):  

   - **+10V**: Reference voltage output (10V DC)  

   - **GND/ACM**: Common ground  

   - **AI1/AVI**: Analog voltage input terminal  

2. **Potentiometer Wiring**  

   A potentiometer has three terminals (assuming ①, ②, ③):  

   - **Terminal ①**: Connect to the converter’s **+10V**  

   - **Terminal ③**: Connect to the converter’s **GND**  

   - **Terminal ②**: Connect to the converter’s **AI1** (slider terminal, outputs adjusted voltage)  

   **Schematic Diagram**:  

   Potentiometer① ── +10V  

   Potentiometer② ── AI1  

   Potentiometer③ ── GND  

3. **Wiring Requirements**  

   - Use **shielded cables** with a length ≤ 2m. If longer, increase wire diameter and shield with 

a steel conduit.  

   - Avoid parallel routing with high-voltage lines to reduce electromagnetic interference.

 **3. Frequency Converter Parameter Settings**  

Take a common converter (e.g., EV510 series) as an example:  

1. **Enter Parameter Menu**: Press the **PRG** button.  

2. **Select Frequency Reference Source**:  

   - **P0-03**: Set to **2** (external analog voltage input).  

3. **Calibrate Voltage Range**:  

   - **P0-10**: Set maximum frequency (e.g., 50Hz for 10V).  

   - **P0-11**: Set upper frequency source to **1** (controlled by external analog input).  

4. **Save and Exit**: Press **DATA** to save and return to standby.

 **4. Precautions**  

1. **Potentiometer Selection**  

   - **Resistance**: Recommended **1-10KΩ** (follow the converter manual if specified).  

   - **Power Rating**: ≥2W; use 5-10× power for frequent adjustment.  

   - **Type**: Linear potentiometer (non-logarithmic).  

2. **Direction Adjustment**  

   If frequency decreases clockwise, swap the **+10V** and **GND** connections.  

3. **Safety Operations**  

   - Disconnect power before wiring to avoid electric shock or equipment damage.  

   - Gradually adjust the potentiometer after initial power-up and monitor motor operation.

# **5. Common Issue Troubleshooting**  

- **No Frequency Change**: Check loose connections and confirm the parameter is set to 

external analog input.  

- **Frequency Fluctuation**: Ensure shielded cable grounding is good and potentiometer 

resistance ≤10KΩ.  

- **Motor Not Starting**: Verify the converter is powered and the run command is provided 

via external terminals or the panel.

This method enables stable frequency control of the converter through a potentiometer, 

achieving speed regulation of motors in distribution boxes. Terminal labels and parameter 

codes may vary by brand—always refer to the specific manual.  

**Key Terms**:  

- Potentiometer  

- Frequency Converter (VFD)  

- Analog Voltage Signal  

- Shielded Cable  

- Parameter Calibration