Rechner Sensors N-132, Инструкция по регулировке

Страница: 36 / 48

Engineering
14
201202 / 9170613310
2018-11-20·BA00·III·en·09
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
EN
Isolating Switching Amplifier
N-132
6.2 Power Dissipation
The max. power dissipation in rated operation is specified in the data sheets. In practice,
not all devices are operated at a full load. As a result, project engineering is usually
performed at an average power dissipation of 70% (P
70%
).
6.3 Engineering of the Power Dissipation in Cabinets
When installing devices in cabinets, the free flow of air is limited and the temperature
rises. It is important to optimize power dissipation and the heat generated in the cabinet
in order to minimize increases in temperature.
a) Natural convection in closed cabinets
• Application: If the power dissipation is low and the system is installed in a dusty or
harsh environment.
• Calculation of the maximum permissible power dissipation:
The calculated value P
max
must be less than the sum of average power dissipation
values (70 % of the max. power dissipation) of the installed devices: P
max
< Ʃ P
70%
b) Natural convection in open cabinets
• Function: The heat is displaced to an area between the devices by cool air streams.
• Prerequisites:
- Air inlet and outlet openings at the lower and upper ends of the cabinet
- The airflow path must be free of obstructions
• Result: Depending on the version, a value that is double the permissible power
dissipation can be reached as shown under a).
Auxiliary power Max. power
dissipation
70% power
dissipation
1 channel N-132/1-10 U
N
= 24 V DC 0.8 W 0.56 W
N-132/1-01 U
N
= 120 to 230 V AC 1.0 W / 1.3 W 0.70 W / 0.91 W
N-132/1-E-10 U
N
= 24 V DC 0.6 W 0.42 W
2 channels N-132/2-10 U
N
= 24 V DC 1.3 W 0.91 W
N-132/2-01 U
N
= 120 to 230 V AC 1.6 W / 2.0 W 1.12 W / 1.4 W
N-132/2-E-10 U
N
= 24 V DC 1.9 W 1.33 W
P
max
=
D
t * S * K
P
max
[W] Max. permissible power dissipation in the cabinet
D
t [°C] Max. permissible temperature rise
S [m
2
] An unobstructed, heat-emitting surface of the cabinet
K [(W/m
2*
°C)] Thermal conductivity coefficient (painted steel: K = 5.5)