SJ300 Inverter
Derating Curves
The maximum available inverter current output is limited by the carrier frequency and ambient
temperature. The carrier frequency is the inverter’s internal power switching frequency, settable
from 0.5 kHz to 12 kHz. Choosing a higher carrier frequency tends to decrease audible noise,
but it also increases the internal heating of the inverter, thus decreasing (derating) the maximum
current output capability. Ambient temperature is the temperature just outside the inverter
housing—such as inside the control cabinet where the inverter is mounted. A higher ambient
temperature decreases (derates) the inverter’s maximum current output capacity.
Use the following derating curves to help determine the optimal carrier frequency setting for
your inverter, and to find the output current derating. Be sure to use the proper curve for your
particular SJ300 inverter model number.
SJ300 1.5 to 22 kW at 50 deg. C ambient
2
4
6
8
10
12
14 15
0.5
65%
70%
75%
80%
85%
90%
95%
100%
Carrier Frequency (kHz)
%
of Driv
e’
s Rated Amps
004 to 150L
185L
220L
SJ300 30 to 55 kW at 50 deg. C ambient
2
4
6
8
10
12
14 15
0.5
65%
70%
75%
80%
85%
90%
95%
100%
Carrier Frequency (kHz)
% of Dri
ve’
s Rated
Amp
s
370L
300L
450L
550L
450L
550L
