350V DC /700V DC Grid

General

The voltage levels are nominal voltages this is excluding the droop range defined by the Current/OS to define the State Of Balance (SOB) of the grid.

The nominal voltage tolerance can be maximal 1.4%. The Grid is isolated from the AC grid and have it's own grounding system.

The arguments:

Why 350V DC

  • With ± 30VDC Droop the limit for direct touch disconnect time = 3 millisecond. So can be used in Home applications. In line with the IEC60479-2
  • Clear number and labeling not confused by AC voltage levels in hybrid cases
  • Similar design criteria's as 230V AC
  • Makes it possible to replace the AC system
  • Improvement in distribution in buildings
  • Easy to convert existing AC designs to DC (based on Current/OS)
  • In case for bipolar ±350V DC the 700V DC levels is available for larger power devices

Why 700V DC

  • Isolation windings in motors is in the safe range
  • Clear number not confused by AC
  • Similar design criteria's as 400 .. 480V AC
  • Lifetime improvement with 1200V semiconductors and capacitors
  • In case for bipolar ±700V DC  the 1400V DC levels is below the 1500V DC border this enable full range of the low voltage band (1500V DC) to use

Voltage levels and applications

There is a lot of discussion about the correct voltage level. This is not simple. It's important to select a level that is universal and can be used for different application, this is why we selected 350V/700V as the level that has the lowest compromises between the applications.

Low Power DC Grids  350V

Applications

  • Homes
  • Offices
  • Outdoor Public services

Voltage levels

High Power DC grids 700V

Applications

  • Distribution
  • Greenhouses
  • Industrial applications

Voltage levels

 

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(corrected version 17102017)