11 - PVD3627-August 2011
3. TECHNICAL DATAS
3.1. Motor selection
3.1.1.
From 0 to1000 m :
no derating
Altitude derating
From 1000 to 4000 m :
torque derating of 5% for each step of 1000 m
3.1.2.
Water cooled motor
Temperature derating
Typical values are given with a water inlet temperature of 25°C and a temperature
gradient Inlet-Outlet of 10°C. These references lead to a winding overheating of
90°C
corresponding to a winding temperature of
115°C
.
It is possible to increase a little bit the Inlet temperature up to 40°C, but the torque
must be reduced. The following formula gives an indicative of the torque derating at
low speed. But in any case refer to SSD Parker technical department to know the
exact values
At low speed
the torque derating is given by the following formula for an water Inlet
temperature > 25°C.
C
C
e
temperatur
Inlet
C
derating
Torque
°
°
−
°
=
90
)
_
115
(
*
100
[%]
_
At high speed, the calculation is more complex, and the derating is
much more important.
Please refer to Parker to know the precise data of Torque derating
according to water inlet temperature at high speed for a specific motor.
N.B.
No general rules can be applied concerning the torque derating of MGV motors
at high speed
. Please refer to Parker for each case.
In fact, the torque derating at high speed also depends on :
- the flux weakening ratio which leads to a short circuit current inherent in the
motor (no action can reduce its value),
- the maximal speed of the motor which determines the iron losses and
mechanical losses due to the rotation.
