Frequency; Safety And Dedicated Ground; Grounding Requirements; Ac Receptacle Requirements - HP XP20000/XP24000 Manual

Avoid the use of a line voltage conditioner.
Make sure that a power distribution unit (if used) provides the correct voltage to support your entire
system.

Frequency

Usually, AC line frequency is determined by your local power providers. In some cases, electrical
power is supplied by generators. Shifts in AC line frequency can cause system errors. An HP
representative can monitor the frequency of the input AC line power and make recommendations, if
necessary. The HP system requires that the line frequency fall within these limits: 50 Hz ±3 Hz or 60
Hz ±2 Hz.

Safety and dedicated ground

The primary reason for earth grounding electrical systems is safety. The safety ground is required by
the National Electric Code (USA) and most other local, regional, and national codes. In addition to
safety ground, HP requires that a dedicated (earth reference) ground be installed as a common
reference point for all system components. Consult with an HP representative and your electrician to
ensure that your electrical system meets all local and national safety codes.

Grounding requirements

Your site's electrical subsystem must meet all of the following conditions:
• Earth grounding as prescribed by your local country codes.
• An insulated grounding conductor that is identical in size and insulation material and thickness
to the ungrounded branch-circuit supply conductors. It should be green, with or without yellow
stripes, and is to be installed as a part of the branch circuit that supplies the unit or system. This
means the ground conductor must be run in the same conduit, armored cable, or other cable
bundle as the phase wires.
• The grounding conductor should be grounded to earth at the service equipment or other acceptable
building earth ground such as the building frames (in case of a high-rise steel-frame structure).
• IT-configured grounding systems are not certified for use with the HP system as these grounding
systems may not have solidly conductor-connected grounded power systems and/or they may
have resistive impedance inserted in ground and/or neutral lines. The HP system requires a solidly
conductor-connected ground and may require a separate neutral in the case of WYE or STAR
connections. For the HP system, TN grounding systems are preferred.

AC receptacle requirements

When receptacles are used to connect disk array components to AC power, they must include a
dedicated ground connection that is insulated from the receptacle. It is important that the receptacle
box be grounded with an additional ground connection that is separate from the dedicated ground.
The additional ground can be hard conduit.
CAUTION:
When installing the receptacles, the electrician must ensure that each receptacle has its own neutral
(if required) and ground. Using the same neutral/ground for more than one circuit causes voltage
loss and heat problems and can create a fire hazard. A shared neutral conductor that fails open-circuit
can cause over voltage damage to equipment.
40 Site requirements for the HP Disk Arrays