Page 212 - B_ELSB_Cat_2022_01_MCBs

1/212 ELECTRICAL INSTALL ATION SOLUTIONS FOR BUILDINGS - TECHNICAL DETAILS 9AKK 107991 A8329
1

—
MCBs technical details
Use of MCBs in altitude and different network frequency

Performance in altitude of MCBs pressure, therefore the performances of the MCBs undergo
Up to the height of 2000 m, MCBs do not undergo any derating, which can basically be measured in terms of
alterations in their rated performances. Over this height variations in significant parameters, such as the maximum
the properties of the atmosphere change in terms of operating voltage and the rated current.
composition, dielectric capacity, cooling capacity and

Miniature circuit breaker
Altitude [m] 2000 3000 4000 5000
Rated voltage U U 0.887 x U 0.775 x U 0.676 x U
n n n n n
Rated current I I n 0.96 x I n 0.93 x I n 0.90 x I n
n
The derating of the rated voltage is valid for AC and DC voltages.

Variation of tripping thresholds of MCBs according to network frequency
The circuit-breakers are calibrated for a current with a frequency range between 50 and 60 Hz.
AC DC
100 Hz 200 Hz 400 Hz
Multiplier 1.1 1.2 1.5 1.5

The thermal tripping performance is independent from the network frequency.

Example:
S 202 C10 supplied at 50-60 Hz, the electro-magnetic tripping current is: 50 A≤Im≤100 A;
S 202 C10 supplied at 400 Hz, the electro-magnetic tripping current is: 75 A≤Im≤150 A.