Derating Curves - Hitachi SJ2002 Series Instruction Manual

1–12
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 2 kHz to 14 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.
An inverter may be mounted individually in an enclosure or side-by-side with other
inverter(s) as shown below. Side-by-side mounting causes greater derating than
mounting inverters separately. Graphs for either mounting method are included in this
section. Refer to
dimensions for both mounting configurations.
Use the following derating curves to help determine the optimal carrier frequency setting
for your inverter and find the output current derating. Be sure to use the proper curve for
your particular SJ200
Legend for Graphs:
"Ensure Adequate Ventilation" on page 2–11
Individual Mounting
Enclosure
SJ200
2
inverter model number.
2
Ambient temperature 40°C max., individual mounting
Ambient temperature 50°C max., individual mounting
Ambient temperature 40°C max., side-by-side mounting
for minimum clearance
Side-by-side Mounting
Enclosure
SJ200 SJ200
2 2