Esson utilization factor

Esson's utilization factor , also Esson's number , Esson's coefficient of performance or Esson's factor , is often abbreviated with C and is used in the design and evaluation of electrical machines . It is defined as follows:

${\displaystyle C={\frac {P_{i}}{D^{2}\cdot l\cdot n}}}$

With

• C = Esson's utilization factor, unit: resp. ${\displaystyle {VA\cdot {\frac {min}{m^{3}}}}}$ ${\displaystyle {W\cdot {\frac {min}{m^{3}}}}}$
• P _i = internal power of the e-machine
• n = speed in 1 / min
• D = diameter of the rotor
• l = length of the rotor

An alternative rating number is the rotary thrust .

Factors influencing the utilization rate

• Size (more powerful machines achieve higher utilization)
• Type of construction (multi-pole electric machines have higher utilization)
• cooling

Typical values

Rated output up to 30 kW: 2–3 kVA min / m ³ With water-cooled motors, up to 10 kVA min / m ³ can be achieved.

Individual evidence

1. ↑ Increase in the utilization of small electrical machines (dissertation)

literature

• Rolf Fischer: Electrical machines , ISBN 978-3-446-40613-1