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Siemens Industry Online Support
Siemens AG
Entry type: FAQ Entry ID: 22978972, Entry date: 11/15/2014
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MICROMASTER 4 (MM4): power losses and temperature rise

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Applies to MICROMASTER 4

What are the power losses of MICROMASTER Drives and accessories and how is temperature rise calculated?

Like all electrical equipment, inverter drives produce waste heat. This heat must be removed to prevent the drive overheating. As most commercial electronics is limited to 70°C (the internal junction temperature must be limited to 125°C or 150°C, but is usually maintained below this), the maximum temperature of the cooling air surrounding, or supplied to the drive is therefore limited to 50°C. For some types and applications, this is reduced further to 40°C (see operating instructions and specification for details).

It is normal to install the drives, together with other equipment, in a cabinet or similar installation. The temperature of the air inside the cabinet must therefore be calculated.

In some cases, cooling air may be supplied by an external fan or ducting. In these cases, the calculation will need to account for the amount of air, as well as its temperature.

As part of the design of the installation, the following steps should allow the calculation of the temperature rise, and a suitable cooling system selected.

  1. Determine the total power dissipated in the cabinet under worst case conditions (= ambient temperature in the cabinet).
  2. Determine the maximum temperature of the air outside the cubicle, or the temperature of the air fed to the cubicle if ducted air is used.
  3. Calculate the temperature rise. If this is too high, consider a different cooling solution (see PDF_additional_text).

Details to calculate the temperature and power losses are in the attached file.

  pdf_power_loss_and_temperature_rise_en_v1_5.pdf (378,5 KB)

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