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ACS550 User’s Manual
217
Technical Data
Derating
The load capacity (current and power) decreases for certain situations, as defined
below. In such situations, where full motor power is required, oversize the drive so
that the derated value provides sufficient capacity.
For example, if your application requires 15.4 A of motor current and a 8 kHz
switching frequency, calculate the appropriate drive size requirement as follows:
The minimum size required = 15.4 A / 0.80 = 19.25 A
Where: 0.80 is the derating for 8 kHz switching frequency (see "Switching Frequency Derating"
below).
Referring to I
2N
in the ratings tables (page 215), the following drives exceed the I
2N
requirement of 19.25 A: ACS550-x1-023A-4, or ACS550-x1-024A-2
Temperature Derating
In the temperature range +40 °C
…
50 °C (+104 °F
…
122 °F) the rated output current
is decreased 1% for every 1 °C (1.8 °F) above +40 °C (+104 °F). The output current
is calculated by multiplying the current given in the rating table by the derating factor.
Example
If the ambient temperature is 50 °C (+122 °F) the derating factor is
100% - 1%/°C x 10 °C
=
90% or 0.90.
The output current is then 0.90 x
I
2N
or 0.90 x
I
2hd
.
Altitude Derating
In altitudes from 1000
…
4000 m (3300
…
13,200 ft) above sea level, the derating is 1%
for every 100 m (330 ft). If the installation site is higher than 2000 m (6600 ft) above
sea level, please contact your local ABB distributor or office for further information.
Single Phase Supply Derating
For 208…240 Volt series drives, a single phase supply can be used. In that case, the
derating is 50%.
Switching Frequency Derating
If the 8 kHz switching frequency (parameter 2606) is used, either:
•
Derate P
N
/P
hd
and I
2N
/I
2hd
to 80% or
•
Set parameter 2607
SW
FREQ
CTRL
= 1 (
ON
) which allows the drive to reduce the
switching frequency if/when the drive’s internal temperature exceeds 90 °C. See
the parameter description for 2607 for details.
If the 12 kHz switching frequency (parameter 2606) is used, either:
•
Derate P
N
/P
hd
and I
2N
/I
2hd
to 65%, and derate ambient temperature maximum to
30 °C (86 °F), and note that the current is limited to a maximum value of I
2hd
, or
•
Set parameter 2607
SW
FREQ
CTRL
= 1 (
ON
) which allows the drive to reduce the
switching frequency if/when the drive’s internal temperature exceeds 80 °C. See
the parameter description for 2607 for details.