Power Dissipation; Engineering Of The Power Dissipation In Cabinets - RECHNER SENSORS N-132 Bedienungsanleitung

Engineering
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6.2

Power Dissipation

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The max. power dissipation in rated operation is specified in the data sheets. In practice,
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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
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1 channel
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2 channels
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6.3

Engineering of the Power Dissipation in Cabinets

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When installing devices in cabinets, the free flow of air is limited and the temperature
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rises. It is important to optimize power dissipation and the heat generated in the cabinet
in order to minimize increases in temperature.
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a) Natural convection in closed cabinets
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• Application: If the power dissipation is low and the system is installed in a dusty or
harsh environment.
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• Calculation of the maximum permissible power dissipation:
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P
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max
P
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max
Dt [°C]
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S [m
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K [(W/m
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The calculated value P
values (70 % of the max. power dissipation) of the installed devices: P
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).
14
Isolating Switching Amplifier
N-132
Auxiliary power
N-132/1-10 U
N-132/1-01 U
N-132/1-E-10 U
N-132/2-10 U
N-132/2-01 U
N-132/2-E-10 U
= Dt * S * K
[W] Max. permissible power dissipation in the cabinet
Max. permissible temperature rise
2
] An unobstructed, heat-emitting surface of the cabinet
2*
°C)] Thermal conductivity coefficient (painted steel: K = 5.5)
must be less than the sum of average power dissipation
max
Max. power
dissipation
= 24 V DC 0.8 W
N
= 120 to 230 V AC 1.0 W / 1.3 W
N
= 24 V DC 0.6 W
N
= 24 V DC 1.3 W
N
= 120 to 230 V AC 1.6 W / 2.0 W
N
= 24 V DC 1.9 W
N
).
70%
70% power
dissipation
0.56 W
0.70 W / 0.91 W
0.42 W
0.91 W
1.12 W / 1.4 W
1.33 W
< Ʃ P
max
201202 / 9170613310
2018-11-20·BA00·III·en·09
70%