7-1. Maintenance and inspection standard
Maintenance and overhaul inspection (repairs)
• Change in machine use pattern
In general, the structure or function of a machine can age or be worn out after using for a long time even though
there has been no breakdown.
Even though a chiller is still in operation after a long time use, the insulation in the motor can be deteriorated or ro-
tation parts can be worn out by the secondary products caused by carbonization or degradation of oil.
Such change in machine use pattern can often be detected externally by vibration or abnormal sound. In this case,
it is critical to take preventive measures by keeping the operation in moderate status in order to prolong the lifes-
pan of the machine.
• Overhaul Inspection(repair) time
Generally, machine failure rate is distributed as shown in the figure below.
The breakdowns occurring in operation during the <initial breakdown period>, which are caused by faulty manufac-
turing, should be prevented by checking in the factory before shipping out.
After a certain amount of time is passed during the < Stable period>, it enters into the <Breakdown period by
wearout> following the change of machine use pattern. In this stage, the failure rate increases drastically, there-
fore, conducting the overhaul inspection(repairs) just before this stage will prevent accidents and allow the opti-
Accordingly, we recommend you to conduct the overhaul inspection(repair) as follows, based on the statistics accu-
mulated for a long time.
1) Machines exclusively used for air conditioning : every 5 years
2) When used in the factory process, where it is continuously operated throughout the year, or used in important
usages requiring a high reliability : every year
• Criteria of overhaul inspection(repair)
An accident can occur when uncontrollable abrasion or deformation passes the limit of any part of a machine.
For example, an over-worn bearing with its oil film destroyed will have a direct contact with metal and highly likely
cause damage to the bearing.
Therefore, LG Electronics set the criteria for (1)use limit and (2)replacement, and based upon this criteria, made up
"Overhaul inspection(repair) criteria". Based on this, LG Electronics conducts inspection to the components or
making replacement as needed.
Overhaul inspection (repair) time
Figure 56 Machine failure rate