VFD parameter setup: the five that matter

Every drive has a hundred parameters and you need about six of them. More importantly: parameter numbers are not portable between firmware revisions, so this page teaches the concepts and tells you where to find each one — rather than handing you a list to copy.

Why no number table. Search for any popular drive model and you will find three different parameter lists for it, all confident. The same model ships with different firmware; a number that sets rated voltage on one unit sets something else on another. A copied list that is 90% right is how you end up with a spindle that hums and trips. Find the parameter by name in your own manual, in the section your manual calls motor parameters or basic parameters.

The five, and what each one does

Motor parameters — take every value from the spindle nameplate, not from a seller's listing
Parameter	What it tells the drive	Wrong value looks like
Rated voltage	The output voltage to reach at base frequency	Too low: no torque and it trips on load. Too high: the motor saturates, overheats, and current climbs
Rated current	Where the overload protection sits	Too low: trips while cutting. Too high: no protection at all
Rated frequency	The base frequency — the top of the constant-torque region	Wrong base frequency skews the whole V/f curve
Poles, or rated speed	Converts output frequency into displayed rpm	Displayed speed wrong by a factor; nothing else affected
Maximum output frequency	The ceiling the drive will not command above	Spindle cannot reach its rated speed, or it is commanded past what its bearings allow

If your nameplate gives rated speed rather than poles, you can get the poles back from the synchronous speed relation — the speed calculator does it for you. Nearly all router spindles reaching 24,000 rpm at 400 Hz are two-pole.

The V/f curve, in one paragraph

Below base frequency the drive holds the ratio of voltage to frequency constant, which keeps the magnetic flux in the motor constant, which keeps the available torque constant — this is the constant-torque region. Above base frequency the output voltage has nothing left to rise to, so flux falls as frequency rises and available torque falls in proportion: the constant-power region, also called field weakening. Everything on the speed and torque page follows from that one sentence.

The other settings worth touching

Acceleration and deceleration time. Too short and you trip on overcurrent accelerating or overvoltage decelerating. A spindle has real rotating inertia; a few seconds is normal for a router spindle, more for a heavy one.
Carrier (switching) frequency. Higher makes the motor quieter and the drive hotter; lower does the reverse and slightly reduces leakage. There is no universally correct value — set it by ear and by drive temperature. See grounding and noise if you are chasing electrical noise.
Command source. Panel, external terminals, or analog input. When the control panel works but your controller does not, this is usually the setting.
Minimum frequency. Worth setting above zero on fan-cooled spindles: a self-cooled motor turning slowly moves little air while still carrying current.

A commissioning order that works

Restore factory defaults. Do this first, always — you cannot tell what a second-hand drive has in it.
Enter the five motor parameters from the nameplate.
Set command source to the panel.
Run at low frequency with no tool. Confirm direction.
Raise to maximum in steps; watch output current.
Set acceleration and deceleration by experiment, from generous downwards until it trips, then back off.
Switch the command source to your controller and confirm the analog reference behaves.

Symptom to parameter, quickly: trips with no load → rated voltage or rated current wrong. Trips when decelerating → deceleration time or brake resistor. Hums and does not turn → a missing phase or a wrong voltage. Speed display wrong → poles. Full triage on the fault codes page.

Parts

Control parts

Questions

Which parameters must I set before first power-up?

The motor nameplate values: rated voltage, rated current, rated frequency and rated speed, plus the maximum frequency. Everything else can wait until it runs.

Why is the spindle rough or weak at low speed?

Usually the V/f curve or the torque boost. A straight V/f line tuned for the top of the range leaves too little voltage at the bottom.

Do I need to run an autotune?

If your drive offers one and you are running in vector mode, yes. In V/f mode it is optional, and the numbers it needs come from reading the nameplate correctly first.

Sources and method

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

Derived — parameters are named by function and never by number — the numbers move between firmware revisions of the same model.
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 series — adjustable speed electrical power drive systems
IEC 60034-1 — rotating electrical machines: rating and performance
NEMA MG 1 — motors and generators
The manual for your own drive and spindle — the only valid source for maker-specific values