INTIP09

Use this procedure to check the AC electrical power for the system.

1. Have an installation planning representative or an electrician (when necessary), perform the following steps.
2. Power off the server and the power network branch circuits before performing this procedure.
3. To ensure the safety of personnel, all electrical wiring in the United States must meet National Electrical Code requirements.
4. Check ALL system receptacles to ensure that each is wired correctly. This includes receptacles for the server and all equipment that attaches to the server, including workstations. Do this to determine if a wire with primary voltage on it has been swapped with the ground wire, causing an electrical shock hazard.
5. When three-phase voltage is used to provide power to the server, correct balancing of the load on each phase is important. The units should be connected so that all three phases are used equally.
6. The power distribution neutral must return to the "separately derived source" (uninterruptable power supply, service entrance transformer, system power module, motor generator) through an insulated wire that is the same size as the phase wire or larger.
7. The server and its attached equipment should be the only units that are connected to the power distribution network that the server gets its power.
8. The equipment that is attached to the server, such as workstations and printers, must be attached to the power distribution network for the server when possible.
9. Check all circuit breakers in the network that supply ac power to the server as follows:
   • Ensure that the circuit breakers are installed tightly in the power panel and are not loose.
   • Feel the front surface of each circuit breaker to detect if it is warm. A warm circuit breaker may be caused by:
     • The circuit breaker that is not installed tightly in the power panel.
     • The contacts on the circuit breaker that is not making a good electrical connection with the contacts in the power panel.
     • A defective circuit breaker.
     • A circuit breaker of a smaller current rating than the current load which is going through it.
     • Devices on the branch circuit which are using more current than their rating.
10. Equipment that uses a large amount of current, such as: Air conditioners, copiers, and FAX machines, should not receive power from the same branch circuits as the system or its workstations. Also, the wiring that provides ac voltage for this equipment should not be placed in the same conduit as the ac voltage wiring for the server. The reason for this is that this equipment generates ac noise pulses. These pulses can get into the ac voltage for the server and cause intermittent problems.
11. Measure the ac voltage to each unit to ensure that it is in the normal range.

    Is the voltage outside the normal range?

    • No: Continue with the next step.
    • Yes: Contact the customer to have the voltage source returned to within the normal voltage range.
12. The remainder of this procedure is only for a server that is attached to a separately derived source.
    

    Some examples of separately derived sources are an uninterruptable power supply, a motor generator, a service entrance transformer, and a system power module.

    The ac voltage system must meet all the requirements that are stated in this procedure and also all of the following:

    Notes:

    1. The following applies to an uninterruptable power supply, but it can be used for any separately derived source.
    2. System upgrades must not exceed the power requirements of your derived source.
    The uninterruptable power supply must be able to supply the peak repetitive current that is used by the system and the devices that attach to it. The uninterruptable power supply can be used over its maximum capacity if it has a low peak repetitive current specification, and the uninterruptable power supply is already fully loaded. Therefore, a de-rating factor for the uninterruptable power supply must be calculated to allow for the peak-repetitive current of the complete system. To help you determine the de-rating factor for an uninterruptable power supply, use the following:

    Note: The peak-repetitive current is different from the "surge" current that occurs when the server is powered on.
    The de-rating factor equals the crest factor multiplied by the RMS load current divided by the peak load current where the:

    • Crest factor is the peak-repetitive current rating of the uninterruptable power supply that is divided by the RMS current rating of the uninterruptable power supply. If you do not know the crest factor of the uninterruptable power supply, assume that it is 1.414.
    • RMS load current is the steady state RMS current of the server as determined by the power profile.
    • Peak load current is the steady state peak current of the server as determined by the power profile.

      For example, if the de-rating factor of the uninterruptable power supply is calculated to be 0.707, then the uninterruptable power supply must not be used more than 70.7% of its kVA-rated capacity. If the kVA rating of the uninterruptable power supply is 50 kVA, then the maximum allowable load on it is 35.35 kVA (50 kVA multiplied by 0.707).

    When a three-phase separately derived source is used, correct balancing of the load as specified in step 5 is critical. If the load on any one phase of an uninterruptable power supply is more than the load on the other phases, the voltage on all phases may be reduced.

13. If the system is attached to an uninterruptable power supply or motor generator, then check for the following:
    • The system and the attached equipment should be the only items that are attached to the uninterruptable power supply or motor generator. Equipment such as air conditioners, copiers, and FAX machines should not be attached to the same uninterruptable power supply, or motor generator that the system is attached.
    • The system unit console and the Electronic Customer Support modem must get ac voltage from the same uninterruptable power supply or motor generator to which the system is attached. This ends the procedure.