High Efficiency Motor

      Motor performance is determined by the output power (Watt Output) divided by power input (Watt Input), or in the way around. The other way, the input power subtracted by the loss power (Watt Loss) divided by input power, designating that 1 horsepower in mechanics domain equals to 746 Watt in electrics domain. The only way to enhance motor performance is to reduce the several losses. The losses from motor, when it does not receive burdens or works (No Load Losses), will be generated in the constant values while motor receives the input power, i.e., the friction loss appearing at motor ball bearing, the loss from air force from motor cooling fan, the loss form rotor air force (for Open Motor IP23), and the loss from metal core, consisting of Hysteresis loss and Eddy Current loss in the magnetic-motor circuit. The loss from motor without loads is around 30% of the overall of each motor loss, and occurs not whether motor spins freely or in the motor working mode. The loss when motor has to receive the burdens or loads     

      Load losses at stator or rotor are the result of resistance of materials used to produce the conductive stator. The conductor at rotor and magnetic circuit of motor can be controlled the loss by selecting the appropriate materials. For the loss from the burden of work process, it is the result from harmonics. And the loss caused by eddy current can be control by the design and the production control process.

Improve the properties of the metal core to be better
    General motor will use the laminated steel, low carbon, for the part of metal core at rotor and stator. The according steel has the electrical power loss 3 Watt per pound (weight). In case of high efficiency motor, it will use high-grade Silicon steel, which is the type reducing power loss from eddy current in half. In other words, there will be the remaining loss only 1.5 Watt per pound.

Use thinner coating steel
    The reduction of metal-sheet thickness used to make the cores of rotor and stator also reduces the power loss due to the eddy current to be less. Moreover, the improvement between the metal sheets will also help reduce these losses to be better.    

Increase the amount of copper conductor 
    The conventional old motor will use Aluminum wire as the conductor to fitting the size of maximum electrical current of motor. But high efficiency motor will use Copper wire as the conductor in order to decrease the resistance in the wire. Plus, the size will also be bigger than the old around 35-40%.

Improve the design of slot gap
    In order to provide the area for the more Copper coils and the more insulators as needed, the cross-section area of the slot gap has to be expanded out around 50%. To offset with the cross-section area, the stator core has to be extended as well. The more length of the core that is longer than the original gives the more important benefit of improving Power Factor of motor to be better.  

Improve the rotor insulator
   Some of the power loss will occur unintentionally from the motor manufacturing process, causing the undesirable electrical current path in the conductor at the rotor. Mostly, this will occur when the rotor conductor is made to be slant, which is the normal design for reducing noise and unstable toque in the small-size motor. In the manufacture of high efficiency motor, the edge of rotor slot will be used high-temperature insulator in order to reduce this loss.

Design more efficient fan
   Because high-efficiency motor will operate at the lower temperature than normal, resulting in the smaller cooling fan, power-loss reduction due to the wind, and less noise.

Motor selection for a replacement
   Another expensive lesson is the motor change by using higher-efficiency motor without consideration by not evaluating whether the current-used motor should be replaced or not. The criterion of changing the old motor with the better high-efficiency motor is detailed in section: motor selection for a replacement (Retrofit). 
Motor selection for a replacement (Retrofit
   The following various criteria should be taken into consideration for selecting priority for old-generation motor that can be replace by the high-efficiency motor. 
General conditions 
   Observe the damage on the body of the motor or insulation. If the motor has passed new wiring in several times or when operating, there is heat, damage history of ball bearing, or else, this type of motor is suitable to be replaced with high-efficiency motor. 

Characteristics of the load support 
  Motor working with full loads or almost is the type that should be selected most in principle. However, the replacement by a small type of motor or the motor sized close to the real load use instead of motor that has the bigger size than load a lot can also provide the energy saving as well







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