Derating Curves - Hitachi SJ100 Instruction Manual

1–12
SJ100 Inverter Specifications

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 16 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 SJ100 inverter model number.
Legend:
SJ100–002NFE/NFU
% of rated
output current
SJ100–004NFE/NFU
% of rated
output current
Standard ratings at 40°C
Ratings at 50°C max. with top cover removed
Ratings at 55°C max. with top cover removed
100%
95%
90%
85%
80%
75%
70%
0.5 2 4
100%
95%
90%
85%
80%
75%
70%
0.5 2 4
6 8 10 12
Carrier frequency
6 8 10 12
Carrier frequency
kHz
14 16
kHz
14 16