IBM i 830 Repair Manual page 351

causing an electrical shock hazard. Use the procedures for checking
receptacles in Electrical Safety for IBM Service Representatives, S229-8124.
2. When three-phase voltage is used to provide power to the iSeries 400 system,
correct balancing of the load on each phase is important. Each unit in the
iSeries 400 system uses only two of the three phases. Therefore, the units
should be connected so that all three phases are used equally. Use the
following as a guide to help balance the phases:
v Connect a unit across phases A and B
v Connect a unit across phases B and C
v Connect a unit across phases A and C
v Continue in this sequence for additional units
3. The power distribution neutral must return to the "separately derived source"
through an insulated wire that is the same size as the phase wire or larger.
Note: "Separately derived source" is defined in INT-PIP8 Grounding, step 4
on page 335.
4. The iSeries 400 system and its attached equipment should be the only units
that are connected to the power distribution network that the system gets its
power.
5. The equipment that is attached to the iSeries 400 system, such as workstations
and printers, must be attached to the power distribution network for the
system when possible.
6. Each unit in the iSeries 400 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.
7. Check all circuit breakers in the network that supply AC power to the iSeries
400 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.
8. 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 400 system. The reason for this is that this
equipment generates AC noise pulses. These pulses can get into the AC
voltage for the iSeries 400 system and cause intermittent problems.
9. Measure the AC voltage to each unit to ensure that it is in the normal range.
Is the voltage outside the normal range?
No Yes
Chapter 3. Problem Isolation Procedures (PIPs), Failing Items, and Symbolic FRU Isolation
Intermittent PIPs
337