IBM i 830 Repair Manual page 352

Intermittent PIPs
10. The remainder of this procedure is only for an iSeries 400 system that is
11. If the system is attached to an uninterruptable power supply or motor
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iSeries Model 830, 840, SB2, and SB3 Problem Analysis, Repair and Parts V5R1
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Contact the customer to have the voltage source returned to within
the normal voltage range.
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 400 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.
Note: 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 400 system
as determined by the power profile.
v Peak load current is the steady state peak current of the iSeries 400 system
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 2 of this procedure 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.
generator, then check for the following:
v The system and the attached equipment should be the only items that are
attached to the uninterruptable power supply or motor generator.