IBM iSeries Series Hardware Problem Analysis And Isolation page 125

9. The equipment that is attached to the iSeries system, such as workstations and printers, must be
attached to the power distribution network for the system when possible.
10. Each unit in the iSeries system must have a circuit breaker that controls only the ac voltage to that
unit. No other equipment may get its ac voltage from the same circuit breaker.
11. Check all circuit breakers in the network that supply ac power to the iSeries system as follows:
v Ensure that the circuit breakers are installed tightly in the power panel and are not loose.
v 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.
12. 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 iSeries system. The reason for this is that this equipment generates ac noise
pulses. These pulses can get into the ac voltage for the iSeries system and cause intermittent
problems.
13. Measure the ac voltage to each unit to ensure that it is in the normal range.
Is the voltage outside the normal range?
v No: Continue with the next step.
v Yes: Contact the customer to have the voltage source returned to within the normal voltage range.
14. The remainder of this procedure is only for an iSeries system 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:
a. The following applies to an uninterruptable power supply, but it can be used for any separately
derived source.
b. 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 iSeries
system 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:
v 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.
v RMS load current is the steady state RMS current of the iSeries system as determined by the
power profile.
Analyze hardware problems
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