7400 Series UPS User Manual Chapter 6 - Troubleshooting
Single Module and One plus One Systems Troubleshooting UPS System
6310018a.02.doc
6-1
Issue 2
(02/98)
6. Chapter 6 - Troubleshooting
6.1 Troubleshooting UPS Systems
The UPS contains complex electronic control circuits that require a firm
understanding in order to carry out comprehensive fault diagnosis and
repair of the equipment. The following information aims to provide a
trained user with sufficient knowledge to understand the nature of a fault
through the correct interpretation of the accompanying alarms and
indications, and to carry out any necessary first aid repair action.
WARNING
Some of the instructions in the charts at the end of this chapter involve checking internal
fuses. This should be undertaken (after the equipment has been shut down) only by a
trained electrician who is familiar with the layout and operation of the equipment and
fully conversant with the areas of potential hazard .
There is no practical way of detecting an impending UPS malfunction.
Most problems do not emerge as a gradual performance degradation;
generally the UPS either works correctly or it will shut down - and
transfer the load to the bypass supply if applicable. However, it is
important to maintain a regular record of the UPS meter indications, as
suggested in the maintenance instructions, in order that any change in the
system or load characteristics are readily identified.
In general, the output voltage should be within 2% of nominal. If the
UPS has not operated on battery power within the previous ten hours the
battery charge current should be typically less than 6A.
If any indication differs significantly from the typical figures given above
the cause should be investigated.
Information concerning prevailing load conditions can prove useful
when discussing problems with the service agent - for example, details of
any particular load being started or shed at the time that the fault
occurred.
Troubleshooting should be carried out methodically using the following
guidelines:
Fault Identification
When first summoned to the scene of a UPS fault, your immediate action
should be to observe and record the displayed messages, mimic
indications, meter indications and the position of the UPS power isolator
switches. This should be completed before you touch any switch.
6.1.1 Operating parameters
and limitations
6.1.2 General
Troubleshooting
Procedure
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