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Electric Motor Selection24
Reading the nameplate, the power–speed–torque relationship, efficiency classes, frame and mounting dimensions, and choosing the right motor for the machine.
- 1. What does the information on an electric motor nameplate mean?
- 2. Does the kW on the nameplate show power consumption or shaft power?
- 3. Why do two electric motors of the same power draw different currents?
- 4. Why is the actual speed of a 1,500 rpm electric motor different?
- 5. What changes if I choose a 2-, 4- or 6-pole electric motor of the same power?
Electric Motor Connection and Starting20
230/400 V and 400/690 V ratings, star-delta connection, starting methods, phase and voltage problems, thermal protection.
- 1. Should a 380 V electric motor be connected in star or delta?
- 2. What happens if an electric motor is wrongly connected in delta instead of star (or the other way round)?
- 3. Can a 50 Hz electric motor be used on a 60 Hz supply?
- 4. How does low supply voltage affect an electric motor?
- 5. What happens if an electric motor is left running on two phases (phase loss)?
Using Electric Motors with Inverters18
Speed control with an inverter, torque and cooling at low and high speed, motor cable, filters, bearing currents and choosing an inverter for the application.
- 1. How does an inverter change an electric motor's speed?
- 2. Can HEM Motor electric motors be used with an inverter (frequency converter)?
- 3. Should an electric motor on an inverter be connected 230 V delta or 400 V star?
- 4. Can a single-phase (220 V) electric motor be driven by an inverter?
- 5. What happens to electric motor torque and cooling when speed is reduced with an inverter?
Electric Motor Maintenance and Overheating20
What IP55 and class F mean, why a motor overheats, signs of faults, bearing maintenance and commissioning a motor after long storage.
- 1. What does IP55 on the electric motor nameplate mean, and can higher protection be ordered?
- 2. What does class F insulation mean?
- 3. At what ambient temperature and altitude does an electric motor deliver full power?
- 4. What changes in selection if the electric motor will run inside a closed cabinet or a narrow compartment?
- 5. How is cooling maintained for an electric motor running in a dusty environment?
Gearbox Selection and Use21
Choosing the gearbox type and ratio, output speed and torque, service factor, motor–gearbox coupling, oil, noise and heating.
- 1. Should I choose a worm gearbox or a helical gearbox?
- 2. What is the difference between bevel-helical, foot-mounted helical and parallel-shaft gearboxes?
- 3. Should I buy the gearbox together with the electric motor, or can I use my existing one?
- 4. Does a worm gearbox hold the load by itself, can it replace a brake?
- 5. How do I choose the gearbox ratio?
Price, Quotation, Order and Delivery15
Prices and VAT, information needed for a quotation, stock and delivery, payment, invoicing, documents and factory visits.
- 1. What information should I send to get an electric motor price quote?
- 2. Do the electric motor prices on the website include VAT?
- 3. What determines the price of an electric motor?
- 4. Which payment methods can I use when ordering an electric motor?
- 5. How can I buy electric motors wholesale or apply to become a dealer?
Electric Motor Faults1
Burnout, tripping, humming, speed and current problems: practical answers from symptom to cause, safe checks and choosing a replacement motor.
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Electric Motor Power, Current and Calculations1
Motor current, kW to HP conversion, torque and power sizing: formulas, tables and worked examples based on HEM Motor catalogue values.
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The Right Electric Motor for Each Machine and Plant1
Practical answers on choosing the right speed, mounting and starting method for pumps, extractor fans, compressors, saws, extruders, presses and other machines.
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This page groups the questions we are asked most often about HEM Motor electric motors and gearboxes under six topics. Click a question to open its answer on its own page; to see every question on a topic, click the topic title or the “show all” link.
Send the motor power, speed, mounting type and quantity on WhatsApp. If you are replacing an existing motor, you can also send a photo of its nameplate.
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