Derating For Ambient Temperature - Data Valid For ≤ 10 Hp [7.5 Kw]; Derating For Low Air Pressure; Derating For Running At Low Speed - Danfoss FC 300 Design Manual

FC 300 Design Guide
Special Conditions
"
Derating for Ambient Temperature - data
"
valid for ≤ 10 HP [7.5 kW]
The ambient temperature (T
measured over 24 hours must be at least 9°F [5ºC] lower.
If the adjustable frequency drive is operated at temperatures above 122ºF [50 ºC], the continuous
output current should be decreased according to the following diagram:

Derating for Low Air Pressure

"
In case of low air pressure, the air cooling
capability is decreased.
Below an altitude of 3280 ft. [1000 m],
no derating is necessary.
Above 3280 ft. [1000 m], the ambient temperature
(T ) or max. output current (I
AMB
derated in accordance with the shown diagram:
Derating of output current versus altitude
1.
at T = max. 122°F [50°C]
AMB
2. Derating of max. T
at 100% output current.

Derating for Running at Low Speed

"
When a motor is connected to an adjustable frequency drive, it is necessary to check
that the cooling of the motor is adequate.
At low RPM values, the motor fan is not able to supply the required volume of air for cooling. This problem
occurs when the load torque is constant (e.g. a conveyor belt) across the regulating range. The reduced
68
FC 300 Selection
) is the maximum temperature allowed. The average (T
AMB,MAX
) should be
VLT,MAX
versus altitude
AMB
MG.33.B6.22 - VLT is a registered Danfoss trademark
)
AMB,AVG