Hitachi GR2000 - Manual (Page 392)

8.2.3.1 Input Unit (AC or DC)
1. Turn off the power switch (AC input) or the breaker switch (DC input) on the
Input Unit and unplug the power cord from the Input Unit.
2. Follow the instructions illustrated in Figure 8-4. Although the figure shows the
case of AC input, the same instructions apply to the case of DC input.