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Is terminals temperature of NSX250 DC, still within the limit 120 degree C when NSX250 DC carries 180A at 70 degree C

 As per the IEC60947-1 , table 2, the rise-temperature for tin platted copper is 65°K. So, at 40°C ambient temperature, the temperature on the terminals will reach at max 40+65=105°C, for a device which is new. Also, as per the IEC60947-2, table 7, the rise-temperature for terminals for external connection can reach at max 80°K for a device which has followed test sequences I to VI, So, meaning in fact that the device is almost in end of its life.   According the catalogue, for an ambient temperature 70°C, a derating in current must be applied at 180A for NSX250DC TM250DC >500V. Such derating will not allow to exceed 105°C on the device' terminals with 40°C ambient temperature, when the device is new. 
If the device has been already operated combined with short circuit as all the tests performed as are described in the IEC test sequences, with 80°K then the terminals could reach 40+80=120°C. So, the derating in current of 180A defined will allow not exceed 120°C in such conditions.

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