10 - PVD 3661 MGV_ commisionning manual_March 2012.docx
3. TECHNICAL DATA
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
.
Recommendations regarding condensation issues are given at § 3.6.
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 about 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.
Illustration of the torque derating vs. temperature at low speed for a MGV motor:
Torque Derating vs. Inlet temperature
90
92
94
96
98
100
102
25
30
35
40
Inlet temperature [°C]
Tor
que
de
ra
ti
ng [
%
]
Torque derating at low speed [%]
