Product Life - Hitachi MICRO-EHV+ Applications Manual

Chapter 5 Maintenance
5.2

Product Life

The lifetime of electrolytic capacitors used in the power module is limited. If the lifetime is exceeded, performance of
product is not guaranteed. Be sure to conduct inspection and maintenance as follows.
(1) Power module
Many electrolytic capacitors are used in the power module. It is said that lifetime of electrolytic capacitor would be
half when ambient temperature increases 10 C.
If lifetime of electrolytic capacitor is exceeded, output power becomes unstable especially when output current is
high due to many point of outputs are activated for example.
Prepare spare units with considering 5 years lifetime in case ambient temperature is 30C. For longer lifetime, take
account of installation location in terms of temperature and air circulation around the unit.
(2) Battery
A battery to maintain realtime clock data and retain memory is available. Be noted following points about lifetime
of battery.
- The battery life as shown below is total power failure time of PLC.
- When OK LED blinks, replace a battery to new one.
As a guideline, replace a battery every two years even when the total power failure time is less than the guaranteed
value shown in the table.
Guaranteed value (MIN) @55C
Battery life (Total power failure time) [year]
Actual value (MAX) @25C
5 10
5 – 2