User manual

130 • vacon parameter descriptions
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9
NOTE! To comply with UL 508C requirements motor over-tempera-
ture sensing is required at installation if the parameter is set to 0.
Note: If you use long motor cables (max. 100m) together with small drives
(<=1.5 kW) the motor current measured by the drive can be much higher than
the actual motor current due to capacitive currents in the motor cable. Con-
sider this when setting up the motor thermal protection functions.
13.8 MTP:AMBIENT TEMPERATURE
When the motor ambient temperature must be taken into consideration, it is
recommended to set a value for this parameter. The value can be set between
-20 and 100 degrees Celsius.
13.9 MTP:ZERO SPEED COOLING
Defines the cooling factor at zero speed in relation to the point where the mo-
tor is running at nominal speed without external cooling. The default value is
set assuming that there is no external fan cooling the motor. If an external fan
is used this parameter can be set to 90% (or even higher).
If you change the parameter P1.4 (Motor nominal current), this parameter is
automatically restored to the default value.Setting this parameter does not af-
fect the maximum output current of the drive which is determined by param-
eter P1.7 alone.
The corner frequency for the thermal protection is 70% of the motor nominal
frequency(P1.2).
The cooling power can be set between 0 - 150.0% x cooling power at nominal
frequency. See Figure 9.18.