Siemens SINUMERIK 840D sl Manual page 19

Guidelines
If the convection area A [m
then use:
● "Heat dissipation using natural convection and internal turbulence" for hot spots and heat
concentrations in housings subject to space constraints. The total power loss P
thermally critical applications can be determined as follows:
– Current measurement for a 24 V supply voltage
– Power loss P
● Heat dissipation using open-circuit ventilation
Calculation of the volumetric flow
The power loss (thermal) dissipated by the components in an operator unit is to be dissipated
using open-circuit ventilation. The volumetric flow V required for this should be calculated at
a difference in temperature of T
Figure 1-2
Operator panel front: OP 012
Manual, 09/2016, A5E36371591B
] does not suffice for the "heat dissipation using natural convection",
2
[W] = U (24 V) * |measured value in ampères|
Ltot
- T
2
Calculating heat dissipation for PCU 50.5 with OP 019
General information and networking
= ΔT ≥ 10K.
1
1.2 Application planning
for
Ltot
19