Every rule, written down.

Four possible outcomes

Each specification you enter is judged separately against each motor, producing one of four outcomes.

A motor that fails a requirement outright is not shown at all. Excluded motors are not weak answers ranked low — they are not answers, and burying them in a long list would only make the real candidates harder to see.

The rules

Rated power

An exact kW match is confirmed. Within ±10% is reported as a difference, stating the percentage and whether the motor is larger or smaller, because that affects full-load current and therefore overload and cable sizing. Beyond ±10% the motor is excluded.

Poles

Matched exactly, or excluded. Pole count sets the speed, so a different pole count is a different machine rather than a near miss. There is no tolerance band here on purpose.

Voltage

Confirmed if your voltage is among those the registration is rated for. If it is not, but is within ±10% of a rated voltage, it is reported as a difference — induction motors generally tolerate about that much supply variation, but running off nominal affects torque, temperature rise and efficiency, so it is your call rather than ours.

Frame

An exact IEC designation such as 132M is confirmed. A motor with the same centre height but a different length letter — 132S against your 132M — is reported as a difference: the shaft sits at the same height, but the foot mounting holes are at a different spacing along the base and the motor is a different length overall. Any other frame size is excluded.

Mounting

Confirmed if the arrangement you asked for is among those the registration covers, and marked family-level if the registration lists several. Where a registrant simply wrote "All Mounts" without listing codes, BecSpec will not read that as confirmation — it is reported as something to verify.

Enclosure (IP rating)

Both IP digits are ordinal scales, so a rating at least as high on both digits satisfies your requirement: IP56 confirms a request for IP55. Where a motor is better on one digit and worse on the other, that is a genuine trade-off rather than a pass, so it is reported as a difference and you are told which way each digit went.

Checks that always appear

Six items appear on every result whether or not you asked about them, because the register cannot answer them and each one decides whether a motor is actually usable:

• Shaft dimensions — not recorded. For a standard IEC design the frame number fixes these, which is what makes frames interchangeable between manufacturers; but the dimension table sits in a copyrighted standard we cannot reproduce, and special-purpose motors depart from it.
• Terminal box position — not recorded. One of the most common replacement mistakes is a motor that is mechanically correct in every dimension but cannot be wired sensibly once bolted down.
• Full-load speed — not recorded. We show synchronous speed calculated from the pole count; the motor runs slower under load because of slip.
• Duty and starting — not recorded. No duty rating, permitted starts per hour or service factor.
• Variable speed drive suitability — not recorded. Nothing indicates whether a motor is rated for inverter supply.
• Registration currency — flagged where a registration has expired or carries no expiry date.

How results are ordered

Ordering is a consequence of the outcomes above, applied in this fixed sequence:

1. Most requirements confirmed at model-specific level.
2. Then fewest differences.
3. Then fewest family-level values.
4. Then fewest items to verify.
5. Then higher full-load efficiency, then manufacturer name alphabetically.

The same search always returns the same order. There is no hidden score, no personalisation, and no commercial weighting. See vendor neutrality.

When BecSpec cannot read what you typed

An entry the rules cannot interpret is not treated as a requirement nothing satisfies. If you enter a frame designation or IP rating in a form BecSpec does not recognise, that requirement is set aside, you are told so above the results, and matching proceeds on the criteria that were readable.

This matters because the alternative is worse than useless: an unreadable entry would otherwise exclude every motor in the register, and the tool would report "no matches" — a far stronger claim than "I did not understand that".

What was excluded

Above every result set is a count of how many motors were excluded and which requirement ruled each one out. Each motor is excluded by the first requirement it fails, so those figures show where a requirement is doing the most narrowing. If a search returns too little, that panel tells you which constraint to relax first.

Specification guide