What does a buyer check before selecting an electric motor?
They check power and speed against the driven load, the frame size and mounting against the machine, and the efficiency class, because minimum efficiency levels are now mandatory in most markets. Frame and mounting decide whether it is a drop-in replacement.
A maintenance engineer needs a motor that will bolt straight onto an existing machine without modification.
Reviewed 4 August 2026
Scope and specifications
- Rated power and speed
- The basic duty specification.
- Frame size and mounting arrangement
- Determines whether it fits without modification.
- Efficiency class
- Mandatory minimum levels apply in most markets.
- Enclosure and ingress protection rating
- Decides suitability for the environment.
- Insulation class and temperature rise
- Governs life at the operating temperature.
- Duty type
- Continuous, intermittent and short-time ratings differ.
- Voltage, frequency and connection
- Must match the supply and the starter.
Documents buyers may need
| Document | What it proves | Where it belongs |
|---|---|---|
| Motor datasheetAsked at: selection | Power, speed, current, efficiency, power factor and dimensions | Publish it |
| Routine test certificateAsked at: acceptance | Electrical tests on the delivered motor | Per shipment |
| Efficiency class certificationAsked at: regulatory compliance | Conformity with the mandatory efficiency level for the market | Publish it |
| Type test reportAsked at: technical evaluation | Full performance testing of the design | Name it, share on request |
| Dimension drawingAsked at: mechanical design | Frame, shaft and mounting dimensions | Publish it |
| Hazardous area certificationAsked at: hazardous installations | Certification for explosive atmospheres where required | Name it, share on request |
| Declaration of ConformityAsked at: before sale in regulated markets | Conformity with the applicable directives | Publish it |
Details for a useful enquiry
- Power, speed and voltage required
- The core duty.
- Driven equipment and load characteristics
- Starting torque requirements vary enormously.
- Frame and mounting required
- Determines fit.
- Environment and protection rating
- Wet, dusty and hazardous areas change the motor.
- Efficiency class required
- Often set by regulation or corporate policy.
- Motor being replaced
- The fastest route to a correct offer.
Questions suppliers ask
What is the most useful page for a motor manufacturer?
A dimension and frame table cross-referenced to the standard frame designations. Most motor purchases are replacements, and the buyer's question is whether yours fits the existing base. A table answers it in seconds and gets found by dimension searches.
How should efficiency be presented?
As the class under the standard the market recognises, with the measured efficiency at full and part load. Efficiency classes are regulated, so the class is a legal statement, and the part-load figures are what an engineer uses to estimate real running cost.
Do buyers need hazardous area information on the main page?
Enough to know whether a certified version exists and to which protection concept. Hazardous area buyers are a specific market with hard requirements, and being findable by them is worth far more than the space it takes.
Check which documents and standards your buyer needs; requirements vary by market, customer and contract.
Plact Research. Plact's editorial desk for buyer-evidence research. Industry standards, documents and buyer questions are researched and drafted with Plact's AI tools, then reviewed by Praveen Kavuri before publication. Every claim cites the standard, regulation or public source it rests on.
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