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Calculation of the Total Power Dissipation of Switch Gears: Principle

Calculation of the total power dissipation is effected on the basis of the following calculation basis and methods:

Thermal design

The basis for the power dissipation calculation is the definition of general conditions per project or per enclosure, with the following factors being considered in Rittal Therm:

The following factors are furthermore required for the "Thermal design" in EPLAN:

All the factors for the definition of the general conditions are properties of the parts or of the part placements whose values the user has to specify correctly in the project planning.

Calculation of the power dissipation of devices and busbars

Specific part properties are evaluated for the calculation of the power dissipation of the individual devices and busbars. The part properties are managed in the EPLAN parts management. These are specifications by the component manufacturer and data that are created and maintained by the user. EPLAN Software & Service does not accept any liability for the correctness of these specifications.

Devices

The power dissipation of a device is calculated in accordance with the formula:

Actual power dissipation of the device = Power loss x Simultaneity factor

The result of the calculation is stored in the Thermal design: Device power dissipation property.

Busbars

The following part properties located on the Busbar tab are evaluated for the calculation of the busbar power dissipation:

Notes:

The following factors are required for the calculation of the busbar power dissipation in Watt [W]:

The busbar power dissipation is calculated with the following formula and entered in the Thermal design: Device power dissipation property:

Formula symbols:

= Busbar operating current in [A]
R(+65°C) = Busbar resistance in [Ω]
l = Rail length in [m]

Total power dissipation

The power dissipations of the installed devices and those of the busbar system are used for each air-conditioning field when the total power dissipation is calculated. The result of the calculation of the total power dissipation is entered in the Thermal design: Total power dissipation for air-conditioning field [n] project property, with "n" being the number of the air-conditioning field.

See also