ENG_124495.XML
Mandatory minimum installation clearances
Ventilation clearances for Sensor Modules and Terminal Modules
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Sensor Modules and Terminal Modules can be mounted directly adjacent to one another.
When mounted on the wall, line reactors and line filters require a ventilation space of 100 mm (3.94 in) above and below respectively.
Ventilation clearances for blocksize format components
The Power Modules PM240‑2 can be mounted side by side. A side clearance of 1 mm (0.04 in) is recommended for tolerance-related reasons.
The ventilation clearances for Power Modules PM240‑2 frame sizes FSA to FSC are:
- Top: 80 mm (3.15 in)
- Bottom: 100 mm (3.94 in)
- Front: 0
The ventilation clearances for Power Modules PM240‑2 frame sizes FSD to FSG are:
- Top: 300 mm (11.81 in)
- Bottom: 350 mm (13.78 in)
- Front: 100 mm (3.94 in)
Ventilation clearances for booksize format components
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Line Modules 5 kW up to 55 kW Active Interface Modules Motor Modules up to 85 A
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Active Line Modules 80 kW and 120 kW Motor Modules 132 A and 200 A
Ventilation clearances for chassis format components
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Basic Line Modules
G_D211_XX_00024
Active Interface Modules in frame sizes FI and GI
G_D211_XX_00025
Active Interface Modules in frame sizes HI and JI
G_D211_XX_00026
Power Modules, Motor Modules and Active Line Modules in frame sizes FX and GX
G_D211_XX_00027
Active Line Modules in frame sizes HX and JX Motor Modules in frame sizes HX and JX
Calculation of internal control cabinet temperature
Control cabinet with forced ventilation
In a control cabinet with forced ventilation, the heat loss Pv passes to the through-flowing air that then rises in temperature by Δϑ. In the time interval Δt, the air absorbs the heat Q = c × m × Δϑ = Pv × Δt, and at the same time the air volume V flows through the control cabinet (c is the specific heat capacity of the air). Mass m and volume V are linked via density ρ. m = ρ × V applies. When inserted in the formula above, the following equation is obtained: Pv = c × ρ × (V/Δt) × Δϑ
The heat loss Pv, that can be dissipated by forced ventilation, is thus proportional to the volume flow
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that the fan delivers through the control cabinet and the permissible degree of heating Δϑ = Tc-Ta
The heat capacity and density of the air depend on the humidity level and atmospheric pressure. For this reason, the equation is dependent on other parameters. To estimate the temperature rise in the control cabinet in a typical industrial environment, c = 1 kJ/kg × K and ρ = 1.2 kg/m3 can be assumed. This results in the following quantity equation:
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with Δϑ = Tc-Ta
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The temperature Tc as the ambient temperature of the components in the interior of the control cabinet can be estimated with the formula given and must be checked by means of measurements for each application because local hot spots can form, e.g. in close proximity to a source of heat or hotspot caused by unfavorable air circulation.
Control cabinet without forced ventilation
A control cabinet without forced ventilation conducts the heat loss Pv generated in the interior to the surrounding air (external temperature Ta) through the surface. For the heat flow,
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the following applies in the steady state:
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k is the heat transfer coefficient, A is the effective cooling surface of the control cabinet, and Δϑ is the temperature difference between the internal cabinet temperature and the external temperature Δϑ = Tc-Ta
The transfer of heat through the walls of the control cabinet is determined by the heat transfer of the interior air to the cabinet wall, heat conduction within the cabinet wall and heat transfer from the cabinet wall to the external air. The heat transfer is to be calculated by the heat transfer coefficient α, and heat conduction by the heat conductivity λ and the thickness d of the cabinet wall. The resulting equation for the possible heat loss Pv is: Pv = [1/(1/αi + d/λ + 1/αa)] × A × Δϑ = k × A × Δϑ
P
v = k × A × Δϑ
Typical values for the heat transfer coefficient k in the case of control cabinets with walls of painted stainless steel which are up to 2 mm (0.08 in) thick:
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k value
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Stationary (non circulating) air in the control cabinet and stationary (non circulating) external air
α
i = αa = 6 W/(m2 × K)
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approx. 3 W/(m2 × K)
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Circulating air in the control cabinet and non-circulating external air
α
i = 40 W/(m2 × K); αa = 6 W/(m2 × K)
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approx. 5.2 W/(m2 × K)
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The calculating procedures of IEC 60890 (VDE 0660 Part 507) can be used for determining the ambient temperature Tc in the interior of the control cabinet. All heat sources in the control cabinet must be taken into account in the calculation, e.g. Line Modules, Motor Modules, power supplies, filters, reactors. It is important to determine the effective cooling surface dependent on the method of setting up the control cabinet. The standard can also be used for control cabinets with ventilation openings (natural convection).
The estimated temperature Tc and the temperature distribution in the control cabinet should be checked with measurements for every application since local hotspots can form, e.g. in close proximity to a source of heat or a hotspot.
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Control cabinet with air conditioner
The control cabinet emits heat via its surface and the air conditioner.
Manufacturers provide information on the design of the air conditioner, e.g. Rittal:
http://www.rittal.de/produkte/system-klimatisierung/index.asp