How manufacturers can save electricity with electric motors

1. JAVID IQBAL SODAGAR
DGM ELECTRICAL

2. The way an electric motor is designed and the way it is used are
the two determinants that can help save electricity. Let's look at
the design aspect first.
Using Copper Windings in Stator Coils

3. As far as the conductivity of the motor is concerned, it is always
better to go for copper coils rather than outdated aluminum
ones. This is because aluminum's conductivity is lower than
copper's. To keep up with copper coils, aluminum magnet wires
may need larger cross-sections so they can provide the same
level of conductivity. Windings wound with an aluminum wire
may have greater volume compared to a copper wire motor of
the same size.
If you're still using aluminum windings, ensure that the ends of
the aluminum magnet wire are properly connected. Aluminum
oxidizes much faster than other metals, and if powdered
aluminum is exposed to air, it will oxidize fully in just a few days
and leave behind a fine white powder.

4. To make a proper connection that ensures good conductivity,
the oxide layer of the aluminum magnet wire must be pierced
to prevent the aluminum from coming in further contact with
air.
Of course, achieving motor efficiency is more than just
deciding between aluminum and copper windings. Several
manufacturers have developed high-pressure-piercing crimp
connectors to enable better efficiency. This has been done to
help aluminum windings keep pace with their copper
counterparts. While it is possible for motors with aluminum
windings to match the power of copper ones, it takes time and
money. Aluminum also requires more turns and a larger
diameter wire, which may not always be economical.
If the motor is required to work occasionally or for a short
duration, and when efficiency and volume are not of the
essence, using aluminum magnet wires can make sense.
Otherwise, copper windings should always be preferred.

5. Using Copper Bars in the Rotor
When it comes to rotors, copper offers the advantage of efficiency
as well. Copper rotors are preferred for energy-conscious
industries in developed countries and in developing nations
where electricity is often in short supply and costly. Copper
rotors are a better bet compared to aluminum ones in terms of
motor quality, reliability, cost, efficiency and lifespan.

6. Machining Moving Parts with Precision
Machining entails removing material from a compartmental unit to a highly
tolerable substance. Precision machinery is necessary to achieve the highest
tolerance at the smallest measurable degree. Whether it is metal cutting or
coal mining, precision machinery can provide the accuracy needed to
produce materials in the desired quantities. The moving machine parts will
demand timely maintenance for maximum output and efficiency. Maintenance
should only be performed by experts, and an inspection of all parts should be
required.

7. Using High-quality Steel for Rotors and Stators
High-tech electrical steel is essential for manufacturing economical
stators and rotors used in an array of electric-motor applications. This
type of steel ensures high magnetic permeability and low power losses
for top-notch performance. However, power losses in electrical steel
may still occur. Eddy currents, also called Foucault currents, come into
play when a magnetic field is alternated.

8. Keeping the Rotor and Stator as Close as Possible
Through precision manufacturing, manufacturers can keep the rotor and
stator as close as possible without touching. When the rotational speed
reaches several thousands of revolutions per minute, the electrical steel in
the rotor may experience tremendous stress. High stress is especially felt in
areas near the magnet slots, where narrow equipment holds the magnets in
place.
.

9. Rolling steel to a thinner gauge controls these eddy
currents and reduces current losses. This is
especially true of application frequencies beyond the
standard 50 or 60 hertz. With induction motors, the
transfer of energy takes place through the air gap
between the stator and the motor. The air gap is
necessary to minimize resistance. A small air gap will
lead to less energy loss and higher efficiency. The
total flux linkage between the stator and rotor widens
as the air gap decreases. Higher flux linkage results
in decreased energy losses and heightened
efficiency. A smaller gap also helps to avoid noise.

10. The wires in the phase coils of small power motors are thinner.
However, the number of coil turns should be high to increase the
magneto motive force or current density. The resistance of the phase
windings and the power loss density are also higher than in high-power
motors. Therefore, low-power motors with high speeds will require
more magneto motive force. This means more coils will be needed
along with a higher number of turns with a thin wire that produces
higher current density.
More Coils Make Motors More Efficient

11. Using Variable-speed Drives
Variable-speed drives (VSDs) or adjustable-speed drives are heavy
industrial electric motors. Their speed can be adjusted with an external
controller. These drives are used in process control, as they help to
conserve energy in plants that utilize numerous electric motors.
VSDs typically are employed as energy savers in pump and fan
appliances, since they better process operations, especially where flow
control is necessary. They also provide soft-start capabilities, which bring
down electrical stresses and line voltage sags that are generally found in
voltage motor start-ups, particularly when driving high-inertia loads.