STOBER
5 | Technical data
05/2019 | ID 442790.01
37
5.1.3.2
Effect of the surrounding temperature
Derating as a function of the surrounding temperature is determined as follows:
§
0 °C to 45 °C: No restrictions (D
T
= 100%)
§
45 °C to 55 °C: Derating −2.5%/K
Example
The drive controller needs to be operated at 50 °C.
The derating factor D
T
is calculated as follows
D
T
= 100% − 5 × 2.5% = 87.5%
5.1.3.3
Effect of the installation altitude
Derating as a function of the installation altitude is determined as follows:
§
0 m to 1000 m: No restriction (D
IA
= 100%)
§
1000 m to 2000 m: Derating −1.5%/100 m
Example
The drive controller needs to be installed at an altitude of 1500 m above sea level.
The derating factor D
IA
is calculated as follows:
D
IA
= 100% − 5 × 1.5% = 92.5%
5.1.3.4
Calculating the derating
Follow these steps for the calculation:
1.
Determine the highest clock frequency (f
PWM
) that will be used during operation and use it to determine the nominal
current I
2N,PU
.
2.
Determine the derating factors for installation altitude and surrounding temperature.
3.
Calculate the reduced nominal current I
2N,PU(red)
in accordance with the following formula:
I
2N,PU(red)
= I
2N,PU
× D
T
× D
IA