Mandatory minimum installation clearances

Ventilation clearances for Sensor Modules and Terminal Modules

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 (4 in) above and below respectively.

Ventilation clearances for blocksize format components

The PM340 Power Modules can be mounted side by side without sub-chassis components up to an ambient temperature of 40 °C (55 °F). In combination with sub-chassis components and at ambient temperatures of > 40 °C (max. 55 °C) (> 55 °F (max. 131 °F)), the specified lateral minimum clearances must be observed. Where combinations of different frame sizes are concerned, the longer of the two clearances shall apply. A clearance of 30 mm (1.18 in) must be provided at the front and to the left of the mounted Control Unit or Control Unit Adapter on frame sizes FSB to FSF.

Ventilation clearances for booksize format components with internal air cooling

Line Modules 5 kW to 55 kWActive Interface Modules Motor Modules up to 85 A

Active Line Modules 80 kW and 120 kW Motor Modules 132 A and 200 A

Ventilation clearances for booksize format components with external air cooling

Ventilation clearances for chassis format components Basic Line Modules

Active Interface Modules in frame sizes FI and GI

Active Interface Modules in frame sizes HI and JI

Power Modules, Motor Modules and Active Line Modules in frame sizes FX and GX

Active Line Modules in frame sizes HX and JXMotor 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 P_v passes to the through-flowing air that then rises in temperature by ??. In the time interval ?t, the air absorbs the heat Q = c ? m ? ?? = P_v ? ?t, 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 ?. m = ? ? V applies. Used in the above formula, the following equation results: P_v = c ? ? ? (V/?t) ? ??

The heat loss P_v, that can be dissipated by forced ventilation, is thus proportional to the volume flow

that the fan delivers through the control cabinet and the permissible degree of heating ?? = T_c-T_a

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 level of control cabinet heating in a typical industrial environment, c = 1 kJ/kg ? K and ? = 1.2 kg/m³ can be assumed. This results in the following quantity equation:

with ?? = T_c-T_a

The temperature T_c 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 heat source or heat accumulation through unfavorable air circulation.

Control cabinet without forced ventilation

A control cabinet without forced ventilation conducts the heat loss P_v generated in the interior to the surrounding air (external temperature T_a) via the surface. For the heat flow

in the steady state the following applies:

k is the heat transfer coefficient, A is the effective cooling surface of the control cabinet, and ?? is the temperature difference between the internal cabinet temperature and the external temperature ?? = T_c-T_a

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 must be calculated by the heat transfer coefficient ?, and heat conduction by the heat conductivity ? and the thickness d of the cabinet wall. The resulting equation for the possible heat loss P_v is: P_v = [1/(1/?_i + d/? + 1/?_a)] ? A ? ?? = k ? A ? ??

P_v = k ? A ? ??

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:

The calculating procedures of IEC 60890 (VDE 0660 Part 507) can be used for determining the ambient temperature T_c 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 T_c and the temperature distribution in the control cabinet must be checked with measurements for every application since local hot spots can form, e.g. in close proximity to a heat source or heat accumulation.

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

Control cabinet with cold plate cooling

Devices with cold plate cooling dissipate part of the generated heat losses to the surrounding air in the control cabinet (P_{v int}). However, the greatest part is dissipated as P_{v ext} via the backplane designed as a cooling surface – the cold plate – to the external heat sink. The heat losses P_{v ext} heat the cold plate to the temperature T_h that is linked via the thermal resistance R_th with the temperature T_ext of the external heat sink: T_h = R_th ? P_{v ext} + T_ext

To ensure the specified value for the thermal resistance R_th, the supplied heat conduction foil must be used between the cold plate and the external heat sink, the device must be screwed together with the specified tightening torque, and the surface finish of the external heat sink must be maintained. The temperature difference between the cold plate and the external heat sink (T_h - T_ext) must not exceed 40 K, since otherwise mechanical warping can result. The devices with a width of 300 mm (11.81 in) are preferred in cold plate cooling for clocked applications that only briefly require the full rated current, but run on average with a smaller load, corresponding to the derating or less.

For the heat losses P_{v int} given off in the control cabinet, one of the previously named calculation methods can be used for calculating the internal control cabinet temperature T_c.

All calculated maximum temperatures must be ensured by means of measurements under realistic load conditions after setup of the system.

You must ensure that the temperature T_ext of the external heat sink does not exceed the defined limit value on the surface contacting the heat conduction foil. Recommended external heat sink, e.g. Rittal DCP – Direct Cooling Package

http://www.rittal.de

Condensation protection with cold plate cooling

On devices with cold plate cooling, warm surrounding air can condense on the cold surface of the external heat sink. The resulting condensate can cause electrical damage such as leakage current bridges and flashovers. The volume of condensate must be minimized by means of an appropriate temperature of the external heat sink by always maintaining the temperature of the heat sink above the dew point of the surrounding air. This can be achieved either by a permanently set and correspondingly high temperature, or by controlling the temperature of the heat sink in accordance with the surrounding air.