In this example, the derated output current is sufficient, because it is higher 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 ACS180-04x-25A0-4 has an output current of 21 A
at 480 V. The switching frequency derating for this drive type is 0.7 at 8 kHz.
Calculate the derated drive output current:
In this example, the derated output current is sufficient, because it is higher than
the required current.
Technical data 103
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