YASKAWA SIEMENS CNC Series, Maintenance Manual, Serviceman Handbook

Page: 41 / 373

2.1 Designing the panels
2-3
• Even if the ambient temperature requirement is met, the system must not be installed in such
places where it is exposed to direct sunlight, nearby heat sources, or the elements.
• The ambient temperature must be between 5 and 30
℃
taking into account UPS battery’s operating
temperature requirement of 5-40
℃
and the expected temperature rise of 10
℃
.
2.1.2 Thermal design of the enclosures
The enclosure of a panel must hermetically enclose a CNC or other unit and be so designed
as to keep the internal average temperature rise 10
℃
or less.
„ Internal average temperature rise
The internal average temperature rise for a sheet metal enclosure can be calculated as fol-
lows:
Note: Effective surface area means the area of an enclosure’s surface that
can dissipate heat
(excluding such a surface as is in contact with another object).
IMPORTANT
•
Δ
T
: Internal temperature rise
(
℃
)
• P
: Internal heat produced (W)
• qe
: Enclosure’s thermal transfer ratio
(W/
℃
)
• k
: Sheet metal’s thermal transfer constant
(W/m
2
℃
)
With an internal fan
6W m
2
℃
Without internal fan
4W/ m
2
℃
• A
: Enclosure’s effective surface area (m
2
)