FC 300 Design Guide
FC 300 Selection
" Special Conditions
" Derating for Ambient Temperature - data
valid for ≤ 10 HP [7.5 kW]
The ambient temperature (T
AMB,MAX
) is the maximum temperature allowed. The average (T
AMB,AVG
)
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 de crease d according to the following diagram:
" Derating for Low Air Pressure
In ca se of low air pr essure , the air cooling
capability is decreased.
Below an altitude of 3280 ft. [1000 m],
no derating is necessary.
Above 3280 ft. [1000 m], the am bient te
mperature
(T
AMB
) or max. output current (I
VLT,MAX
) should b e
deratedinaccordancewiththeshowndiagram:
1. Derating of output current versus altitude
at T
AMB
= max. 122° F [50°C]
2. Derating of max. T
AMB
versus a ltitude
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 ad eq uate.
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
MG.33.B6.22 - VLT is a registered Danfoss trademark
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