Siemens SINAMICS S120 Equipment Manual page 30

System overview
1.4 Derating factors
Example 1
A drive system comprising Line and Motor Modules is to be operated at an altitude of
2500 m at a maximum ambient temperature of 30 °C.
Since the ambient temperature is below 40 °C, a compensation calculation (installation
altitude/ambient temperature) can be carried out.
Reason:
If the Modules are operated at installation altitudes between 2000 m and 4000 m, the air
density and thus also the cooling capacity of the forced-cooled devices decreases. However,
as the ambient temperatures at the site of installation are often lower, a compensation factor
can be calculated for the units in this case. The reduction in current can be balanced by
correction factor K
greater than 1, the rated current can be used in the calculation. If the multiplication result is
<1, the rated current must be multiplied by this value to yield the maximum permissible
continuous current.
The following formula is used:
I ≤ I
Installation altitude: 2500 m; max. ambient temperature: 30 °C
● Correction factor K
● Correction factor K
● Correction factor K
I ≤ I
I ≤ I
I ≤ I
however I ≤ I
Result:
● Since the result yields a factor of > 1, the current does not have to be reduced
● However, IEC 60664-1 stipulates that voltage derating is required at installation altitudes
● Devices in the voltage range 380 V – 480 V 3 AC can be operated with a maximum
● Devices in the voltage range 500 V – 690 V 3 AC can be operated with a maximum
30
. If the result of multiplying correction factor K
T
x K x K , I ≤ I (I = permissible continuous current, I
N I T N
= 0.965
I
= 1.133
T
= 0.94
U
x K x K
N I T
x 0.965 x 1.133
N
x 1.094
N
N
> 2000 m (6562 ft).
voltage of 0.94 x 480 V = 451 V.
voltage of 0.94 x 690 V = 648 V.
by correction factor K
T
= rated current)
N
Manual, (GH3), 10/2008, 6SL3097-2AE00-0BP3
is
I
Chassis power units