Site Preparation Guide, Second Edition - HP Integrity rx4640 Server

General Site Preparation Guidelines
Electrical Factors
Chapter 2
24
Dual power sources might originate from two different transformers or two different UPS devices. Voltage
potentials from ground pin to ground pin of these sources should be measured and verified to be at or near 0.0
volts. Voltage levels that deviate or are measured above 3.0 volts should be further investigated. Increased
voltages might be hazardous to personnel, and should be further investigated.
Cabinet Performance Grounding (High Frequency Ground)
Signal interconnects between system cabinets require high frequency ground return paths. Connect all
cabinets to site ground.
NOTE In some cases power distribution system green (green/yellow) wire ground conductors are too
long and inductive to provide adequate high frequency ground return paths. Therefore, a
ground strap (customer-supplied) should be used for connecting the system cabinet to the site
grounding grid (customer-supplied). When connecting this ground, ensure that the raised floor
is properly grounded for high frequency.
Power panels located in close proximity to the computer equipment should also be connected to the site
grounding grid. Methods of providing a sufficiently high frequency ground grid are described in the next
sections.