Yaskawa YASNAC PC NC Maintenance Manual - Manual (Page 9)

PC NC Maintenance Manual Chapter 1: General Installation and Electrical Connection
1-6
devices, or outdoors, even if the ambient temperature is within the specified range.
Design of the enclosure should be made on the basis that the average temperature
increase of air within the enclosure (containing the PC NC unit and other compo-
nents) should be 10
o
C below the external air temperature.
(1) Temperature Increase within the Enclosure (Average Temperature Increase)
The internal temperature increase (sheet metal enclosure) is generally as fol-
lows: where,
∆Τ:
Internal temperature increase (
o
C)
P: Heat generation in enclosure (W)
qe: Enclosure heat percolation ratio (W/
o
C)
k: Heat transit ratio of sheet metal (W/m
2o
C)
6W/m
2o
C: With internal cooling fan
4W/m
2o
C: Without internal cooling fan
A: Efficient heat diffusion area of enclosure (m
2
)
Area capable of diffusing heat in surface area of the enclosure
(Excluding area contacting other devices)
Example: Allowable heat generation in the enclosure with internal circulating fan
Figure 1.6: Enclosure Dimensions
Efficient heat diffusion area is independently located, so bottom area is
excluded.
A=4.16m
2.
If the heat generation in the enclosure is supposed to be 246W (113W in the
1200
700
800 All dimensions in millimeters