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HP Netserver High Density Rack Solutions Overview (LP 2000r)
Calculate total input current requirements.
Input current requirements
Once you know the input power needed to operate the servers and other devices installed in the rack, you
can calculate the input current that is required for the rack by using this formula:
Input Power (W)
I n p u t / C u rrent (A) =
AC Voltage (V)
Using this basic formula, you can evaluate whether your PDU, UPS and/or local AC power circuit can provide
the amount of current the equipment connected to it needs.
For example, if you are connecting four servers to a 16 A PDU, you can use the tables above and deter-
mine the total input power requirements for each server. In this example let’s assume we have calculated
these to be:
Server
Total Input Power (W)
HP Netserver LP 2000r #1
176
HP Netserver LP 2000r #2
177
HP Netserver LP 2000r #3
180
HP Netserver LP 2000r #4
180
The total input power requirements for these four servers come to 713 W. By knowing that we are operat-
ing at a line power of 100 VAC and using the formula above we can calculate that the four servers will
require an input current of 7.13 A—well below the capacity of the 16 A rated PDU.
Circuit breakers
The HP Netserver LP 2000r power supply has been designed for low AC inrush current to reduce the pos-
sibility of tripping circuit breakers, typically located at a distribution panel.
Tripping of circuit breakers in the distribution panel may result from use of circuit breakers that are not
adequately rated for inrush current found in most electronic devices. Replacing the circuit breaker with a
suitable type is often the best solution.
The largest inrush current occurs when AC is first applied to the equipment in the rack. Often this inrush
current is independent of the “on” or “off” state of the individual devices. However, you can usually reduce
the total inrush current by applying power to the rack with the equipment in the “off” stage.
Power up sequence
Follow these instructions to minimize inrush currents and to minimize circuit breakers from tripping:
1. Power on peripherals one at a time; beginning with the tape back-up unit, followed by the mass-storage
units, keyboard, video monitor, and mouse switch, if any.
2. If your system includes an HP Console Switch, it must be powered on before the HP Netserver LP 2000r.
3. Last, power on each HP Netserver LP 2000r and wait for the fan in each server to spin up before power-
ing on the next one. If the HP Netserver LP 2000r doesn’t detect all the required components, it will not
complete the boot process and will report an error.
Power down sequence
There is no specific order to power down the equipment in a rack; however, there is an HP recommenda-
tion that it be done in the following sequence:
1. Ensure that the network users are properly warned of the power down.
2. Shut down the Network Operating System.
3. Power down the peripherals.
4. Power down the Netservers.
