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5.2.9 Derating for Air Pressure
Below 1000 m derating is not necessary.
Above 1000 m the ambient temperature (T
AMB
) or max. output current
(I
MAX
) must be derated in accordance with the diagram below:
1.
Derating of output current versus altitude at T
AMB
= max. 40 °C.
2.
Derating of max. T
AMB
versus altitude at 100% output current.
5.2.10 Derating for Running at Low Speed
When a motor is connected to a frequency converter, it is necessary to ensure adequate cooling of the motor. At low rpm values, the motor fan is not
able to supply an adequate volume of cooling air. This problem occurs when the load torque is constant (e.g. with a conveyor belt) across the full regulating
range. The reduced amount of ventilation determines the permissible torque in continuous operation. If the motor is to run continuously at an rpm lower
than half the rated value, extra cooling air must be supplied to the motor. Instead of providing extra cooling, it is possible to reduce the motor load ratio.
This can be done by selecting a larger motor. However, the design of the frequency converter puts limits on the size of motors that can be connected to
the frequency converter.
5.2.11 Motor Cable Lengths
The frequency converter has been tested using a 10 m unscreened/unarmoured cable and a 10 m screened/armoured cable and has been designed to
work using a motor cable with a rated cross-section.
5.2.12 Vibration and Shock
The frequency converter has been tested according to a procedure based on the following standards:
IEC 68-2-6: Vibration (sinusoidal) - 1970.
IEC 68-2-34: Random vibration broad-band - general requirements.
IEC 68-2-35: Random vibration broad-band - high reproducibility.
IEC 68-2-36: Random vibration broad-band - medium reproducibility.
5.2.13 Air Humidity
The frequency converter has been designed to meet the IEC 68-2-3 standard, EN 50178 item 9.4.2.2/ DIN 40040 class E at 40 °C. Cyclic damp heat IEC
68-2-30. 100% humidity with temperature cycling.
5.2.14 UL Standard
This device is UL-approved.
VLT
®
Decentral FCD 300 Design Guide
5 All About FCD 300
MG.90.S1.02 - VLT
®
is a registered Danfoss trademark
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