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Nairobi PowerENGINEERS · EST. 1984

SOLUTIONS / APPLICATION GUIDE

Electric motors

Match the motor to its load, mounting and duty. Compare energy use using your operating hours and tariff before considering a replacement.

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Illustrative electric motors equipment
AI-generated equipment illustration.

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CHOOSE YOUR APPROACH

Start with the application.

Like-for-like replacement

Check frame, shaft, flange, speed, voltage and mounting dimensions before ordering.

Long running hours

Compare efficiencies at the actual load, alongside installed cost and downtime.

Drive-fed applications

Check insulation, bearing protection, cooling and the permitted speed range.

BUILD A USEFUL BRIEF

Bring these details.

  • Clear nameplate and mounting photographs
  • Rated kW, rpm, voltage, current and duty
  • Frame, shaft and flange dimensions
  • Load profile, hours, ambient temperature and ingress protection
Send your project brief ↗
Is matching kW enough for a replacement?

No. Speed, torque, mounting, supply, starting method, duty and environmental requirements must also match.

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COMPONENTS THAT COMPLETE THE APPLICATION

Specify the whole working system.

Start with the equipment duty. Add the control, protection and measurement functions that your project needs; these are options to review, not a pre-approved assembly.

Images are AI-generated illustrations of equipment categories, not LOVATO model photographs. Confirm dimensions and ratings from the selected model datasheet.

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Industrial Electric Motors ↗IE3 Premium Efficiency Motors ↗Three-Phase Induction Motors ↗Single-Phase Electric Motors ↗

METHODS & WORKED EXAMPLES

Understand the estimate.

These examples use the default inputs. Change the live controls above for your own scenario; the reference examples below remain fixed.

Motor energy comparison — worked example

Annual kWh = rated shaft kW × load fraction × annual hours / efficiency fraction. Cost difference uses the entered energy tariff.

Example inputs

  • Rated shaft power: 30 kW
  • Shaft load: 75 %
  • Existing efficiency at duty: 88 %
  • Replacement efficiency at duty: 93 %
  • Annual running hours: 4000 h
  • Energy tariff assumption: 25 KES/kWh
  • Installed replacement cost: 150000 KES

Example result

  • Existing annual energy: 102,272.7 kWh
  • Replacement annual energy: 96,774.2 kWh
  • Annual cost difference: 137,463 KES

Assumptions & limits

  • Both motors deliver the same shaft duty. Use efficiency at this load, not an unrelated nameplate point.
  • Tariff is your scenario input, not a published utility rate.
  • Simple payback excludes finance, maintenance, downtime and tariff changes. Negative difference means higher operating cost.
  • Preliminary planning only. Final selection needs project-specific engineering verification.

Technical reference: US Department of Energy: motor systems guide. This reference does not certify the website calculation or an NPE assembly.

Motor starting current — worked example

Example inputs

  • Motor rating: 55 kW
  • System voltage: 415 V — industrial
  • Phase: 3Φ (three phase)
  • Starting method: Direct on line (DOL)
  • Efficiency: 92 %
  • Power factor: 0.86

Example result

  • Full load current: 96.7 A
  • Starting current: 580 A
  • Starting multiplier assumption: 6 × FLC

Assumptions & limits

  • Starting multipliers are illustrative, not measured inrush or guaranteed torque.
  • Verify motor nameplate, load acceleration, supply limits and starts per hour.
  • Preliminary planning only. Final selection needs project-specific engineering verification.
Geared motor speed & torque — worked example

Output speed = motor rpm / reduction ratio. Output torque (Nm) = 9550 × output shaft kW / output rpm.

Example inputs

  • Motor shaft power: 4 kW
  • Motor speed: 1500 rpm
  • Reduction ratio: 30 :1
  • Gear efficiency: 90 %
  • Service factor assumption: 1.5

Example result

  • Output speed: 50 rpm
  • Output torque: 687.6 Nm
  • Rated torque requirement: 1,031.4 Nm

Assumptions & limits

  • n₂ = n₁ / ratio; T₂ = 9550 × output kW / output rpm.
  • Service factor increases the required gearbox rating, not available torque.
  • Verify thermal capacity, peak torque, shock, mounting and shaft loads with the manufacturer.
  • Preliminary planning only. Final selection needs project-specific engineering verification.

Technical reference: SEW-EURODRIVE drive selection guide. This reference does not certify the website calculation or an NPE assembly.

METHODS & WORKED EXAMPLES

Understand the estimate.

These examples use the default inputs. Change the live controls above for your own scenario; the reference examples below remain fixed.

Three-phase voltage unbalance — worked example

Example inputs

  • L1–L2 voltage: 415 V
  • L2–L3 voltage: 410 V
  • L3–L1 voltage: 420 V

Example result

  • Average line voltage: 415 V
  • Maximum deviation: 5 V
  • Voltage unbalance: 1.2 %

Assumptions & limits

  • Unbalance (%) = 100 × maximum absolute deviation from the average / average.
  • Use line-to-line readings taken under the same operating condition.
  • No pass/fail limit or trip delay is selected. Check equipment limits and investigate supply conditions with a qualified engineer.
  • This method uses voltage magnitudes only; it is not an IEC negative-sequence calculation.
  • Preliminary planning only. Final selection needs project-specific engineering verification.

Method reference: US DOE — Energy Management for Motor-Driven Systems