Technical specifications
6.4 Derating and temperature compensation
3VA molded case circuit breakers
Manual, 04/2015, A5E03603177010-02
497
In addition, a correction factor for setting the magnetic trip unit as a function of frequency
must be applied.
Starting point:
A 3VA1 molded case circuit breaker 100 A with a TM240 trip unit is used for a 400 Hz
application. The molded case circuit breaker is required to trip instantaneously in response to
an overcurrent of 900 A.
The maximum permissible rated continuous operational current is calculated first:
100 A · 0.9 =
The setting value for instantaneous short-circuit protection (I
i
) is then determined on the
basis of the correction factor from the table above:
I
i
= 900 A · 0.7 =