4. Installation specifications
4-2
TI 30A30A10-01EN
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Circuit protector specifications
The table lists the circuit protector ratings used in the N-IO field enclosure.
Model
Name
Built-in circuit protector rating
(A/V)
External breaker rating (A/V)
(*1)
A2NN70D
N-IO field enclosure
30/250
40/250
S2NN70D
N-IO field enclosure
30/250
40/250
n
Parts durability
Some parts require periodical replacements. For preventative maintenance, the recommended
intervals to replace parts with life span of less than 10 years are shown in the table below.
Users can replace parts indicated by “Yes” in the “user replacement”. For other parts, contact
Yokogawa for replacement.
The average ambient temperature shown in the table is the average temperature surrounding the
corresponding parts.
When the parts are installed in an enclosure, though varies with actual installations, in general,
the temperature inside of the enclosure is about 10 °C higher than the temperature outside the
enclosure.
Note: Random failures within the recommended replacement intervals may occur in some parts.
IMPORTANT
The reliability and life span of electronic equipment greatly depend on the operating environment.
It is essential for ensuring reliable operation and prolonged life span that the equipment is used
not only within the range of environment resistance standards but also in a more satisfactory
environment. For instance, if a piece of equipment is always used at 35 °C when its operating
temperature ranges from 5 to 40 °C, generally its estimated failure rate almost doubles compared
with operation at 25 °C.
If corrosive gas is present in the environment, the corrosion of the equipment’s contacts and
printed circuit boards is accelerated more than in a cleaner environment, resulting in a reduced
life span. Moreover, if dust can be easily generated in the environment, filters must be cleaned
and replaced more often.
Feb. 26, 2018-00
