4 ms·

> What practical electric motor is even close to 30% efficient? This is laughably low. I think that means 30% over existing performance.

by mjhay 2y ago

imbusy111 2y ago
Got it, missed that part. Still, assuming efficiency can't get past 100%, 100% boost can be achieved only on something that already has only 50% efficiency.
- kraftman 2y ago
  I assume that they are looking at in laymans terms, and saying that if an electromagnetic motor is 80% efficient, an electrostatic motor could increase efficiency of the remaining 20% by 30% to 100% (86-100% total efficiency). Not that it makes any sense, but I think that was their intention.
  - exe34 2y ago
    i wish people would just always use percentage points and never deviate from that.
    - DoctorOetker 2y ago
      I wish people would just explicitly state they can't believe their eyes that 100% efficiency can be asymptotically reached, i.e. no known law of the universe prevents us from building electromotors that are 90%, 99%, 99.9% etc... absolute efficient. Then we could just remind them that Carnot efficiency does not apply to electrical / mechanical energy conversion.
- DoctorOetker 2y ago
  This is absurd, detecting that a wrong interpretation is inconsistent (because it would result in overunity violation of energy conservation) and instead of rejecting the misinterpretation of the parent, concocting an even more convoluted interpretation. All because people refuse to believe 100% energy conversion between electromagnetic domain and mechanical domain is impossible? Turbosets have been doing this for a long time already, the Carnot efficiency limit does not apply to non-thermal energy conversions...
DoctorOetker 2y ago
THey are in fact talking about absolute efficiency. Conventional electromotors are designed with high efficiency... at a certain range of RPM and torque. For lower RPM's permanent magnet electromotors suffer dramatic decreases in efficiency and torque, unless you use a gearbox, which also produce heat due to frictional loss. These electrostatic motors can achieve quasi reversible performance (i.e. asymptotically close to 100% efficient, not a violation of thermodynamics, since neither electrical nor mechanical energy are thermal forms of energy). Turbosets also reach nearly 100% conversion efficiency. Electrostatic motors started their niche with miniature motors, since they were more compact and it becomes progressively harder to miniaturize winding coils. Where a simple electrode surface would be more space efficient. Pay attention to Macroscale in the title, its these miniature-niche low RPM motors slowly capturing larger torque and higher RPM lebensraum from the gearboxed permanent magnet electromotors.

> What practical electric motor is even close to 30% efficient? This is laughably low. I think that means 30% over existing performance.

by mjhay 2y ago

> What practical electric motor is even close to 30% efficient? This is laughably low. I think that means 30% over existing performance.

imbusy111 2y ago

Got it, missed that part. Still, assuming efficiency can't get past 100%, 100% boost can be achieved only on something that already has only 50% efficiency.

kraftman 2y ago
I assume that they are looking at in laymans terms, and saying that if an electromagnetic motor is 80% efficient, an electrostatic motor could increase efficiency of the remaining 20% by 30% to 100% (86-100% total efficiency). Not that it makes any sense, but I think that was their intention.
- exe34 2y ago
  i wish people would just always use percentage points and never deviate from that.
  - DoctorOetker 2y ago
    I wish people would just explicitly state they can't believe their eyes that 100% efficiency can be asymptotically reached, i.e. no known law of the universe prevents us from building electromotors that are 90%, 99%, 99.9% etc... absolute efficient. Then we could just remind them that Carnot efficiency does not apply to electrical / mechanical energy conversion.
DoctorOetker 2y ago
This is absurd, detecting that a wrong interpretation is inconsistent (because it would result in overunity violation of energy conservation) and instead of rejecting the misinterpretation of the parent, concocting an even more convoluted interpretation. All because people refuse to believe 100% energy conversion between electromagnetic domain and mechanical domain is impossible? Turbosets have been doing this for a long time already, the Carnot efficiency limit does not apply to non-thermal energy conversions...

DoctorOetker 2y ago

THey are in fact talking about absolute efficiency. Conventional electromotors are designed with high efficiency... at a certain range of RPM and torque. For lower RPM's permanent magnet electromotors suffer dramatic decreases in efficiency and torque, unless you use a gearbox, which also produce heat due to frictional loss. These electrostatic motors can achieve quasi reversible performance (i.e. asymptotically close to 100% efficient, not a violation of thermodynamics, since neither electrical nor mechanical energy are thermal forms of energy). Turbosets also reach nearly 100% conversion efficiency. Electrostatic motors started their niche with miniature motors, since they were more compact and it becomes progressively harder to miniaturize winding coils. Where a simple electrode surface would be more space efficient. Pay attention to Macroscale in the title, its these miniature-niche low RPM motors slowly capturing larger torque and higher RPM lebensraum from the gearboxed permanent magnet electromotors.