When should you repair instead of replace?

The answer is simple in principle. Employ the services of Wearside Rewinds to rewind or otherwise repair a motor when it is cheaper than buying a new motor.

Implementing this is a little more tricky because you need to consider the total cost of ownership. Ideally, you have to consider:

• First cost of repair and a new purchase
• Efficiency of existing and proposed new motor
• Availability of a new motor
• Lifetime discounted cost of electric energy for each scenario
• Salvage value of existing motor
• Possible modifications to the mounting
• Cost in downtime and repairs from a possible early failure in either scenario

The key calculation for your decision is the annual energy savings from replacing the motor. This can be calculated by the following formula:

kW_saved = hp x L x 0.746 x (1/E_ex– 1/E_n)

 

where:

hp = Motor nameplate horsepower

L = Load as percent of full rated load

E_ex = Efficiency in percent of existing motor after repair

E_n = Efficiency in percent of replacement motor

Total Electric Dollar Savings =

(kW saved x 12 x Monthly demand charge) + (kW_saved x annual operating hrs x kWh rate)

For standard off-the-shelf motors, the repair scenario can rarely prevail unless the user is assured that the original efficiency is high, that it is maintained through repair, and the repaired motor is as reliable as a new one. These are possible, but not guaranteed.

For more information, please contact Wearside Rewinds at any time.