Environmental Engineering Reference
In-Depth Information
The
air-gap power P
g
can be estimated by:
(5.103)
Ohmic or copper losses in the stator
(5.104)
and iron losses in the stator
P
Fe1
further reduce the air-gap power. The
output
power
(5.105)
is finally fed into the mains.
Speed-Torque Characteristics and Typical Generator Data
The connection between torque and speed for an asynchronous generator is
also interesting because the rotor speed changes with the driving torque. The
intrinsic torque of the machine is used for the following calculations. It is
calculated from the air-gap power
P
g
and the synchronous speed
n
S
of the
stator field as:
(5.106)
The internal torque
M
i
is also given by the mechanical torque
M
(negative sign
in generator mode) and the friction torque
M
f
(positive sign):
(5.107)
With the equation of the current for the simplified equivalent circuit:
(5.108)
the internal torque becomes:
(5.109)
With
(5.110)
