Weq CTW900, Руководство пользователя

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Technical Specifications .
142 | CTW900
10.3 DIMENSIONING OF THE CTW900
In order to dimension the converter CTW900 correctly, it is necessary to take into account the DC motor used,
the load cycle characteristic and the environmental conditions of the application.
Thus, first you must check the rated voltage of the motor armature so as to determine the converter voltage
class, as per Table 10.1.
Then you evaluate the most critical load cycle of the application for a period of ten minutes, and you calculate its
effective current. With this value you determine the converter rated current, which must not be lower than the
effective current of this cycle.
Furthermore, the maximum current peak during the critical load cycle must not be over 125 % of the CTW900
rated current.
Finally, the converter operating ambient temperature and the altitude must be taken into account. In case of
operation at temperatures above 40°C and/or installation at altitudes higher than 1000m above sea level, you
must apply the ratio-corrector factors to the output current of the CTW900, according to Figure 10.1
Figure 10.1 – Ratio-corrector factors of the output current considering the ambient temperature and altitude
Example:
Assuming a motor with armature rated voltage of 400V, ambient temperature of 35 °C, altitude of 500 m and
load cycle as per Figure 10.2, determine the most suitable CTW900 for the application.
Figure 10.2 – Load cycle of the application
1. Considering the motor armature voltage (400 V), in Table 10.1 you can see that a converter class 05 is
enough for the drive.
2.
Analyzing the load cycle of the application, you can see that the motor must drive the load in both
directions (forward and reverse). In this case, the converter must be able to operate in the four
quadrants (4-Q), and thus the most suitable is the CTW900
A .
3. According to the load cycle graph, the period of ten minutes with the highest current corresponds to
periods T1 and T2, and the effective current in this period is calculated as follows: