Altitude derating: The derating factor for 1800 m is
.
Surrounding air temperature derating: Derating is not necessary at 35 °C surrounding
air temperature.
To see if the derated output current of a drive is sufficient for the application, multiply
the nominal output current (I
N
) by all the applicable derating factors. For example, drive
type ACH480-04-12A7-4 has a nominal output current of 12.6 A at 400 V. The switching
frequency derating factor for this drive type is 0.68 at 8 kHz. Calculate the derated drive
output current:
In this example, the derated output current is sufficient, because it is more than the
required current.
Example 2, UL (NEC): How to calculate the required drive
The application requires a maximum of 12.0 A of motor current with a 10% overload for
one minute every ten minutes (I
Ld
) at a switching frequency of 8 kHz. The supply voltage
is 480 V, the altitude is 5500 ft and the surrounding air temperature is 95 °F.
Altitude derating: The derating factor for 5500 ft is
.
Surrounding air temperature derating: Derating is not necessary at 95 °F surrounding
air temperature.
To see if the derated output current of a drive is sufficient for the application, multiply
the drive output current for light-duty use (I
Ld
) by all the applicable derating factors. For
example, drive type ACH480-04-21A-4 has an output current of 21 A at 480 V. The
switching frequency derating for this drive type is 0.67 at 8 kHz. Calculate the derated
drive output current:
In this example, the derated output current is sufficient, because it is more than the
required current.
Technical data 127
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