VFD to spindle wiring diagram

One schematic covering power, earth, brake resistor, run/stop control and speed reference — plus the five wiring mistakes that account for most dead drives.

Power and earth

Single-phase 220 V supply → 220 V three-phase spindle

  Supply                     VFD                          Spindle
  ──────                     ───                          ───────
   L (live)   ───────────►   L1 / R
   N (neutral)───────────►   L2 / S
   PE (earth) ────┬──────►   PE  ──────────────────────►   frame / earth pin
                  │                                          │
                  └──────────────────────────────────────────┘  (bonded, low impedance)

                              U  ─────────────────────────►   U
                              V  ─────────────────────────►   V
                              W  ─────────────────────────►   W
                          (screened 4-core: 3 phases + PE, screen clamped at the drive end)

                             B1 ────┐
                             B2 ────┴──[ braking resistor ]──  (only if fitted)

Substitute L1/L2/L3 for L1/L2 if you have three-phase in. Nothing else about the power wiring changes. The output is still three phases.

Control and speed reference

Run/stop from a controller, speed from 0–10 V

   VFD                              Controller / panel
   ───                              ──────────────────
   FOR  ──────[ relay or switch ]──────  spindle on
   REV  ──────[ relay or switch ]──────  reverse (optional)
   COM  ───────────────────────────────  common for the above

   AI1  ◄───── 0–10 V analogue  ───────  spindle speed command
   GND  ◄───── analogue 0 V     ───────  reference for AI1 (NOT chassis earth)
   +10V ─────► potentiometer top ──────  only for a manual pot
   GND  ─────► potentiometer bottom
   AI1  ◄───── potentiometer wiper

   FA / FB ───[ fault relay ]──────────  to an E-stop chain or indicator

Analog ground and protective earth are different things. Joining them at the wrong point is a reliable way to inject noise into the speed reference — the spindle speed will wander or jump when the drive switches.

Five mistakes, in the order they happen

Wiring faults, symptom, and the cost
Mistake	What you see	Cost
Supply landed on U/V/W	Nothing, then a bang, then nothing	Drive is scrap
Earth not carried to the spindle frame	Works, until someone touches the frame	Safety, and a noise floor you cannot debug
Screen floating or earthed at the spindle end only	Works, but USB/limits drop out under load	Hours of chasing the wrong fault
Brake resistor on the wrong terminals	Overvoltage trip on decel, or a short across the bus	Drive or resistor
Output switched by a contactor	Works a few times, then an output fault	Drive

Sizing the protective conductor

The earth conductor has to be able to carry a fault current long enough for the supply protection to operate, so it is normally specified at least as large as the phase conductors on small drives, and by code above that. Use the sizing calculator for the phase conductor size and match the earth to it as a minimum. Local wiring rules override anything here.

On the brake resistor: the ohms matter in two directions. Too high and it cannot absorb the energy fast enough, so you still get an overvoltage trip. Too low and it draws more current than the braking transistor is rated for, which damages the drive. Every drive has a minimum allowable resistance in its documentation — that number wins over any calculation. See braking resistor sizing.

Checking the work before power

Supply disconnected. Continuity from the supply plug's earth pin to the VFD chassis and to the spindle frame: should be near zero ohms.
Continuity from each of U, V and W to the spindle frame: should be open (or megohms if you have an insulation tester, with the drive disconnected).
Resistance U–V, V–W, W–U: three roughly equal, low readings.
Control wiring: nothing except intended dry contacts across FOR/COM. No voltage sources.
Brake resistor: measured resistance equal to what is printed on it, and not below the drive's stated minimum.

The ten minutes this takes is the cheapest insurance on the whole build. Every one of these checks is a failure that would otherwise present as a mysterious trip weeks later.

Parts

Connectors and cable

Control parts

Questions

Where does the brake resistor go?

Across the drive's DC bus terminals, never on the output. The terminals are usually marked with a + and a brake or B designation — confirm them in your manual, because the letter is not standard.

How do I wire the 0–10 V speed reference?

Analogue reference and analogue common, on a screened twisted pair, routed away from the motor cable. Noise on this pair is the single most common cause of speed that wanders under load.

How big does the earth conductor need to be?

Sized for the prospective fault current of the supply, not for the spindle's load current. On long runs it goes up with the phase conductors rather than staying small.

Sources and method

Three kinds of statement appear on this page, and each is labelled where it occurs:

Derived — the schematic is the conventional one; terminal labels are given by function because the printed labels differ between makers.
Rule of thumb — workshop practice, not a standard. Given with the range it is meant to hold over, and it loses to your manual wherever the two disagree.
Maker-specific — parameter numbers, connector pin numbers, minimum brake resistance, maximum cable length, bearing speed limits. Not published here. They move between firmware revisions of the same model, and a wrong one is worse than none.

Standards and documents

IEC 61800-5-1 — adjustable speed drives: safety requirements
IEC 60204-1 — electrical equipment of machines
IEC 61000-6-2 — EMC immunity for industrial environments
The manual for your own drive and spindle — the only valid source for maker-specific values