2 Functions
74
7UM61 Manual
C53000-G1176-C127-3
Figure 2-18 Example of an Unbalanced Load Characteristic Specified by the Machine Man-
ufacturer
Cooldown Time The parameter 1705 T COOL DOWN establishes the time required by the protection
object to cool down under admissible unbalanced load I2> to the initial value. If the
machine manufacturer does not provide this information, the setting value can be cal-
culated by assuming an equal value for cool-down time and heatup time of the object
to be protected. The formula below shows the relation between the K asymmetry
factor and the cool-down time:
Example:
The following cool-down time results for a K = 20 s and an admissible continual unbal-
anced load I
2
/I
N
= 11 %.
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