
27
2
Operating characteristics and performance
2-4 Performance with current at 100%
2-4 Performance with current at 100%
2-4-1 Temperature rise
At the rated current, the temperature of MCCBs and ELCBs (reference) should not rise above the values given in Table 2-10 at
any specification.
Table 2-10 MCCB and ELCB temperature rise at the rated current
Terminal
Handle
Cover top
IEC 60947-2 Table 7
80K
35K
50K
JISC 8201-2-1, JISC 8201-2-2
80K
35K
50K
UL 489 Table 40.1 (reference)
50K
60K
60K
UL 60947-4-1 Table 2.3 (reference)
65K
35K
50K
2-4-2
Internal resistance and power consumption
The breakers used in AC circuits have the following losses.
1. Resistance loss in conductive parts and contacts
2. Iron loss induced in internal magnetic materials
The losses are so small at commercial frequencies that they
can be ignored as is often done with resistance losses.
Table 2-11 shows average internal resistance per phase as
well as power consumption at the rated current for MCCBs.