The wiring of a frequency converter

1. Power Supply Wiring (Main Circuit)

• Input Power (L1, L2, L3 / R, S, T)
  • Connect the three-phase AC power supply to the input terminals of the frequency converter (marked as L1, L2, L3 or R, S, T). Ensure the voltage and frequency match the converter's rating (e.g., 380V/50Hz).
  • For single-phase input (e.g., 220V), connect to the specified terminals (often L1 and L2), and leave L3 unconnected (check the manual for specific models).
• Output to Motor (U, V, W)
  • Connect the converter's output terminals (U, V, W) to the motor windings. The phase sequence determines the motor rotation direction; swap any two wires to reverse the direction if needed.
  • Use shielded cables to reduce electromagnetic interference (EMI), and keep the cable length within the recommended range (e.g., ≤50m for standard motors).

2. Control Circuit Wiring

• Analog Inputs (e.g., 0-10V, 4-20mA)
  • Connect the analog signal source (e.g., potentiometer, PLC output) to terminals marked "AI1," "AI2," etc. Use twisted-pair cables and ground the shield at one end.
  • Set the converter parameters to match the signal type (e.g., voltage/current mode).
• Digital Inputs (DI1, DI2, etc.)
  • Connect switches or PLC digital outputs to these terminals for functions like start/stop, speed selection, or direction control.
  • Common wiring types:
    • Sinking Input: The signal wire is connected to the negative terminal (COM).
    • Sourcing Input: The signal wire is connected to the positive terminal (24V).
• Relay Outputs (RO1, RO2, etc.)
  • These terminals provide dry contacts for alarms (e.g., overcurrent, overvoltage) or status indication. Connect to a control circuit or indicator light.
• Communication Interfaces (RS-485, Modbus, etc.)
  • For bus communication (e.g., Modbus RTU), connect the data wires (A, B) to the corresponding terminals. Use twisted-pair cables and add termination resistors (e.g., 120Ω) at the bus ends.

3. Grounding and EMI Protection

• Ground Terminal (PE/GND)
  • Connect the converter's ground terminal to a dedicated earth ground with a thick wire (e.g., ≥2.5mm²) to prevent electrical shock and reduce interference.
  • Ensure the grounding path is short and has low resistance.
• EMI Filter and Choke
  • Install an EMI filter at the input to reduce interference to the power grid.
  • Add a reactor or choke at the output for long cable runs (e.g., >100m) to protect the motor from voltage spikes.

4. Safety Precautions

• Power Off Before Wiring: Wait for the DC bus voltage to drop to a safe level (often ≤30V) before connecting wires to avoid electric shock.
• Fuse and Circuit Breaker: Install a suitable fuse or circuit breaker at the input to protect against short circuits.
• Wire Gauge: Use wires with a current rating 1.5–2 times the converter's rated current to prevent overheating.
• Label Wires: Mark each wire for easy troubleshooting and maintenance.

5. Typical Wiring Diagram (Example)

Terminal Type	Function	Connection Example
L1, L2, L3	AC power input (3-phase)	Connect to 380V/50Hz grid via circuit breaker
U, V, W	Motor output	Connect to motor windings (U→T1, V→T2, W→T3)
DI1	Start/stop control	Connect to a normally open switch + 24V COM
AI1	Speed setting (0-10V)	Events news Cases Contacts Contacts: Mrs. Huang Tel: +86-15920127268 Fax: +86-755-23283620 Contact Now Mail Us Send About Us Company Profile Factory Tour Quality Control Contact Us Sitemap Privacy Policy products MPPT VFD Solar Pump Inverter Single Phase Solar Pump Inverter Hybrid Solar Pump Inverter VFD Frequency Inverter VSD Variable Speed Drive Medium Voltage Inverter Contact UsShenzhen ZK Electric Technology Co., Ltd. cindy@zundrive.com +86-15920127268 Guanlida Building, NO. 269 of Qianjin Road, Xin'an street,Bao'an,Shenzhen,Guangdong,China tiktok China Good Quality MPPT VFD Solar Pump Inverter Supplier. Copyright © 2021-2025 Shenzhen ZK Electric Technology Co., Ltd. . All Rights Reserved.