HP 20/700 - Manual (Page 61)

60 Library Power Switch Chapter 2
Library Power Switch
Note Be aware that each PDU supplies power to the robotics and half
of the drives. When the library has two PDUs (and a drive
column with two power cords), each PDU is connected to
separate branch AC circuit.
If you are installing multiple drives in the library (and the library
is a newer model with two power cords to the drive column), HP
recommends that you configure some drives in the upper five
slots, and some drives in the lower five slots in the drive column.
With this configuration, if one PDU loses power, some drives and
the library robotics will remain operational.
The library power switch is a circuit breaker or breakers behind the right front
door of the library. Figure 23 on page 62 shows the power switch location.
This switch, attached to the AC power distribution unit (PDU), controls the AC
power to the library and drive column.
The power switch has two configurations:
■ A single breaker on the AC power distribution unit controls the library and
a single drive column.
■ A second breaker, located on the second power distribution unit, powers
the second drive column and an optional second library power supply.
Note Your library has two circuit breakers:
The second PDU must be connected to a separate electrical
circuit.
If only one breaker is powered off, the second breaker will still
be powered on.