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Characteristics of the inverse time-delay over-current opening releases at the reference temperature of Acti 9 iC60 circuit breakers based on IEC 60898-1 and IEC 60947-2 specifications

Published date: 12 February 2019

The derating table (attached) for the iC60 devices are based on testing with respect to IEC 60898-1 and IEC 60947-2 requirements.

Standard IEC 60898-1:
  • Testing is to be done at temperature reference 30°C
  • Conventional non-tripping current 1.13 x In
  • Conventional tripping current 1.45 x In
  • Conventional time 1h
Standard IEC 60947-2:
  • Conventional non-tripping current 1.05 x In
  • Conventional tripping current 1.3 x In
  • Conventional time 1h
  • Each manufacturer defines the ambient reference temperature.
50°C for MCB compliant with both standards (IEC 60898-1 and IEC 60947-2)
40°C for MCB compliant only with IEC 60947-2
Furthermore, the manufacturer is responsible to include the reference temperature of the test at rated current, printed on the device as follows:

For more information concerning the 2 standards, please visit the blog:

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