￭
Sizing
ABB recommends the DriveSize tool for selecting the drive, motor and gear
combination (https://new.abb.com/drives/software-tools/drivesize). You can
also use the ratings tables.
The minimum recommended nominal current of the motor is 40% of the drive
nominal output current (
I
n
) . If the motor has a lower nominal current rating than
this, the drive cannot accurately measure the motor current.
Output derating
The load capacity (
I
n
,
I
Ld
) decreases in some operation conditions. In such operation
conditions, where full motor power is required, oversize the drive so that the total
derated output current is sufficient for the motor to reach the full power.
In an environment where more than one type of derating is necessary (for example,
high altitude and high temperature), the effects of derating are cumulative.
Note:
•
I
max
is not derated.
• It is possible that also the motor load capacity needs to be derated.
• You can also use the DriveSize tool for derating.
See Surrounding air temperature derating (page 137), Altitude derating (page 137)
and Switching frequency derating (page 138) for the derating values.
Example 1, IEC: How to calculate the derated current
The drive type is ACH480-04-018A-4, which has a nominal output current (
I
n
) of
17 A at 400 V. Calculate the derated output current at 4 kHz switching frequency,
at 1500 m altitude and at 55 °C surrounding air temperature.
Switching frequency derating: Derating is not necessary at 4 kHz.
Altitude derating: The derating factor for 1500 m is
Surrounding air temperature derating: The derating factor for 55 °C surrounding
air temperature is
Multiply the nominal drive output current by all the applicable derating factors. In
this example, the derated output current becomes
Technical data 135
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