What does a buyer check before selecting an electric motor?
Answer
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.
Information to make clear
Use the fields that affect this buying decision. Leave unsupported claims out.
- 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 to prepare
State what can be published, shared on request or issued with an order.
| Document | What it supports | Suggested handling |
|---|---|---|
| Motor datasheetMay be requested at: selection | Power, speed, current, efficiency, power factor and dimensions | Publish |
| Routine test certificateMay be requested at: acceptance | Electrical tests on the delivered motor | Issue per shipment |
| Efficiency class certificationMay be requested at: regulatory compliance | Conformity with the mandatory efficiency level for the market | Publish |
| Type test reportMay be requested at: technical evaluation | Full performance testing of the design | Share on request |
| Dimension drawingMay be requested at: mechanical design | Frame, shaft and mounting dimensions | Publish |
| Hazardous area certificationMay be requested at: hazardous installations | Certification for explosive atmospheres where required | Share on request |
| Declaration of ConformityMay be requested at: before sale in regulated markets | Conformity with the applicable directives | Publish |
Details to ask in an enquiry
Collect only the information needed to assess the request and respond.
- 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.
Related questions
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.
This is an editorial checklist, not a compliance standard. Requirements vary by market, customer and contract. Confirm current requirements with the responsible technical and commercial teams.
Plact Research. Plact's editorial desk for buyer-evidence guides. The guides organize common buyer questions, documents and enquiry fields. Requirements should be checked against current standards, regulations and contracts.