Economics of Replacement vs' Repair

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Economics of Replacement vs. Repair

• Depends on many factors...
• Running hours
• Load
• Cost of electricity
• Cost of new motor
• Cost of motor repair

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Motor Management Policy
Replace
Annual Running Hours
Repair
Size (kW)
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The Real Cost of Rewinding a Motor It is
generally considered that repairing a motor is
the low cost option, but even a good rewind will
reduce motor efficiency by up to 0.5

• Example
• 15kW motor with an Efficiency of 90.0
• Annual running cost 5000.00
• Motor rewound with an Efficiency of 89.5
• Annual running cost 5,028

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The Real Cost of Rewinding a Motor
High Efficiency Motor Efficiency 92.5
High Efficiency Motor Cost Saving
Original Motor Efficiency 90.5
(-) 250
850
1,100
Capital Cost
Rewind Cost
12,973
Annual Running Cost
359
Annual Running Cost - Now 90.0
13,332
Total Cost in First Year
109
14,182
14,073
Total Cost after Two Years
468
27,514
27,046
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A Motor Management Policy

• All new motors to be HEMs
• Make the Repair / Replace decision basedon
  lifetime costs
• Consider replacing working motors with HEMs
• Watch for unnecessary over-sizing

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