Page 28 - SACE Tmax XT - Technical Catalogue

1/24 SACE TMAX XT LOW VOLTAGE MOLDED CASE CIRCUIT-BREAKERS

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Characteristic curves

Example of curves reading

Example 3 - XT2N 160
Limitation curves
The figure below gives the trend of the limitation curves of For a fault current of 20 kA, the XT2N 160 circuit-breaker
the XT2N 160 In=160 A circuit-breaker. The effective value of with a thermal magnetic trip unit In =160 A limits the peak
the prospective symmetrical short-circuit current is given on prospective short-circuit current to 13.5 kA at a voltage of
the x-axis of the graph, whereas the peak value of the 500 V, with a reduction of 36.5 kA in relation to the peak
short-circuit current is indicated on the y-axis. value of the prospective short-circuit current.
The limiting effect can be evaluated by comparing the peak
value corresponding to the prospective short-circuit current
(curve A) with the peak limited value (curve B), at the same
value of symmetrical short-circuit current.

Ip [kA]
10 3

A curve
10 2
50 kA

36.5 kA 160 A
B curve
10
13.5 kA

1
1 10 10 2 10 3
x I rms [kA]