Technical information

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1SDC210033D0202
The circuit-breakers used for power distribution can operate in alternating current at different fre-
quencies from 50/60Hz (frequencies which the rated performance of the apparatus refers to) so
long as the appropriate derating coefficients are applied.
At 400Hz, the performance of the circuit-breakers is reclassified so as to take the following phe-
nomena into account:
Q an increase in the skin effect and increased inductive reactance in a way that is directly propor-
tional to the frequency, overheat the conductors or the copper components that normally carry
the current in the circuit-breaker;
Q lengthening of the hysteresis loop and reduction of the magnetic saturation value, which conse-
quently varies the forces associated with the magnetic field to a given current value.
By and large, these phenomena influence the behaviour of both the thermomagnetic trip units and
the current interrupting parts of the circuit-breaker.
Consult the “Electrical installation handbook” ABB SACE guide for further details.
All the circuit-breakers in the SACE Tmax XT family equipped with thermomagnetic or electronic
trip units (except for the Ekip M-I, Ekip M-LIU and Ekip M-LRIU trip units) can be used in 400Hz
installations. The 10A and 25A settings for operation at 400Hz are only available on request.
Contact ABB SACE for more details about performance derating.
Special applications
400Hz installations