Special Conditions; Derating For Ambient Temperature; Derating For Low Air Pressure; Derating For Running At Low Speeds - Danfoss VLT Micro Drive FC 51 Quick Manual

Quick Guide

1.9 Special Conditions

1.9.1 Derating for Ambient Temperature

The ambient temperature measured over 24 hours should
be at least 5 °C lower than the maximum ambient
temperature.
If the frequency converter is operated at high ambient
temperature, decrease the continuous output current.
The frequency converter has been designed for operation
at maximum 50 °C ambient temperature with 1 motor size
smaller than nominal. Continuous operation at full load at
50 °C ambient temperature reduces the lifetime of the
frequency converter.
MG02BB02
Quick Guide

1.9.2 Derating for Low Air Pressure

The cooling capability of air is decreased at low air
pressure.
CAUTION
INSTALLATION AT HIGH ALTITUDE
For altitudes above 2000 m (6560 ft), contact Danfoss
regarding PELV.
Below 1000 m (3280 ft) altitude, no derating is necessary,
but above 1000 m (3280 ft), decrease the ambient
temperature or the maximum output current.
Decrease the output by 1% per 100 m (328 ft) altitude
above 1000 m (3280 ft), or reduce the maximum ambient
temperature by 1 °C per 200 m (656 ft).

1.9.3 Derating for Running at Low Speeds

When a motor is connected to a frequency converter,
check that the cooling of the motor is adequate.
A problem may occur at low speeds in constant torque
applications. Running continuously at low speeds – less
than half the nominal motor speed – may require extra air
cooling. Alternatively, select a larger motor (1 size up).
Danfoss A/S © 05/2016 All rights reserved.
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