Chapter 7. Maintenance and Inspection
7-2
7.3 Replacing Parts
The following parts undergo aging process as time passes due to mechanical friction or the
characteristics of the material used, leading to the deterioration of equipment performance or
breakdown. Check the parts periodically and replace them, if necessary.
1.
Smoothing condenser:
The characteristics become aged due to the effects of ripple current.
The operating life of the condenser varies significantly depending on ambient temperature and
operating conditions. When used continuously in normal environment, its standard life span is
10 years. The condenser becomes aged fast during a specific period. Inspect it at least once a
year (it is desirable to conduct inspection semi-annually in case the life span is nearing the
exhaustion point).
For judgement criteria, visually check:
a. Case status: Check if the sides and bottom of the case are expanded.
b. Cover plate: Check for significant expansion, severe cracks or damage.
c. Explosion-proof valve: Check for significant expansion or wear.
d. Check periodically the external condition for cracks, tear, discoloration and water-leakage. If
the rated capacity of the condenser drops to 85% or less, it indicates life span has
exhausted.
2.
Relays:
Inadequate contact may occur due to contact wear resulting from switching current.
The relay wear condition is affected by the power capacity. The standard life span is 100,000
accumulated switching (switching life) operations.
3.
Motor bearing:
Replace bearing when it is used for 20,000-30,000 hours under rated speed
and rated load. The motor bearing condition is dependent upon the operating conditions.
Replace the bearing if abnormal noise or vibration is discovered.
[Standard replacement period]
Parts
Standard replacement
period
How to replace
Smoothing condenser
7-8 years
Replace with new parts (Decide after
check)
Relays
-
Decide after check
Fuses
10 year
Replace with new ones
Motor bearing
-
Decide after check
Aluminum electrolytic
condenser on PCB
5 years
Replace with new PCB (Decide after
check)
