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

Quick Guide
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1.9 Special Conditions

1.9.1 Derating for Ambient Temperature

The ambient temperature measured over 24 hours should
be at least 9° F [5°C] lower than the max. ambient
temperature.
If the adjustable frequency drive is operated at a high
ambient temperature, the continuous output current
should be decreased.
The adjustable frequency drive has been designed for
operation at max 122° F [50°C] ambient temperature with
one motor size smaller than nominal. Continuous
operation at full load at 122° F [50°C] ambient temperature
will reduce the lifetime of the adjustable frequency drive.

1.9.2 Derating for Low Air Pressure

The cooling capability of air is decreased at low air
pressure.
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VLT Micro Drive Quick Guide
For altitudes above 6,600 feet [2 km], contact Danfoss
regarding PELV.
Below altitudes of 3,300 ft [1,000 m], no derating is
necessary, but at 3,300 ft [1,000 m] and higher, the
ambient temperature or maximum output current should
be decreased.
Decrease the output by 1% per 328 ft [100 m] higher than
an altitude of 3,300 ft [1,000 m], or reduce the max.
ambient temperature by 1 degree per 656 ft [200 m].

1.9.3 Derating for Running at Low Speeds

When a motor is connected to an adjustable frequency
drive, it is necessary to make sure that the cooling of the
motor is adequate.
A problem may occur at low speeds in constant torque
applications. Running continuously at low speeds – below
half the nominal motor speed – may require additional air
cooling. Alternatively, choose a larger motor (one size up).
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MG02B722 - VLT is a registered Danfoss trademark