vfd wiring diagram
This is a free printable vfd wiring diagram: download the diagram as SVG or open it and print to paper or PDF.
Diagram checks and scope
- Components
- 6
- Wired connections
- 10
- Automated check
- Automated pin, route, source, and topology checks passed; this is not a safety certification.
A VFD wiring diagram provides comprehensive terminal assignments and signal routing for Variable Frequency Drive installations. The diagram maps hardwired inputs, analog speed references, three-phase motor terminals, and communication protocols for plant automation integration.
How to wire vfd wiring diagram
- Review the VFD manual for your specific model Terminal designations, control wiring, and parameter settings vary between manufacturers and models. Do not use a generic diagram for final installation — use the manual supplied with your specific drive.
- Size all cables and protection devices Use the VFD input current (nameplate) to size the incoming cable and MCB. Use the motor full-load current to size the output cable. Account for derating if cables are in conduit or high ambient temperature.
- Install the input isolator and protection Fit an appropriately rated isolator switch and MCB or fuse on the supply side of the VFD. The MCB must be sized for VFD input current — not motor full-load current.
- Mount the VFD with adequate clearance VFDs generate heat and require airflow above and below the unit. Follow the manufacturer's minimum clearance dimensions. Poor ventilation causes over-temperature tripping and premature failure.
- Connect input, earth, and output Wire supply to input terminals, earth to the chassis earth point, and shielded motor cable from output terminals to the motor. Keep input and output cables on opposite sides of the enclosure.
- Connect control wiring Wire all control inputs (start, stop, speed reference, fault reset) and outputs (run, fault relay) using screened cable. Reference the VFD's control terminal diagram for exact pin functions.
- Set motor parameters and perform a no-load test Enter the motor nameplate data (voltage, current, frequency, speed) into the VFD parameters. Run a no-load motor test before coupling the drive to the mechanical load.
Frequently asked questions
What is the difference between VFD input and output wiring requirements?
Input wiring carries standard mains frequency current and can use standard power cable. Output wiring carries high-frequency switched voltage and must use shielded motor cable to contain EMI. Output cable length also affects bearing currents in the motor.
Can I use a standard earth leakage (RCCB) circuit breaker on a VFD supply?
No — VFDs generate high-frequency earth leakage current through internal EMC filters that will nuisance-trip a standard RCCB. Use a Type B RCCB (which detects both AC and DC residual currents) or rely on the VFD's internal earth fault detection.
What is the purpose of a line reactor or input choke on a VFD?
A line reactor (input choke) on the VFD supply reduces harmonic distortion fed back into the mains, protects the VFD from supply voltage transients and notching, and reduces peak rectifier current — all extending VFD service life and improving supply quality.
How should I handle multiple VFDs in the same enclosure?
Run each VFD's motor cable separately — bundling multiple VFD output cables together multiplies the EMI interference. Each VFD needs its own dedicated earth conductor back to the earth bar. Share a common DC bus only if the drives are specifically designed for it.
What is a brake resistor and when does a VFD need one?
When decelerating a load with high inertia, the motor regenerates energy back into the VFD's DC bus, raising DC bus voltage. A brake resistor (connected to the VFD's braking transistor terminals) dissipates this energy as heat, preventing an over-voltage trip.
Sources and verification
Review status: Not independently reviewed. Automated topology checks confirm stored terminals and routes, not the correctness of manufacturer pin assignments, ratings, regional codes, or installation decisions. Verify those claims against the current primary documentation before use.
- IEC 61082-1:2014 — Rules for electrotechnical documents — International Electrotechnical Commission. Supports: General diagram, drawing, table, and reference-designation presentation conventions. Checked 2026-07-15.