Siemens UL 508A Referenzhandbuch - Seite 22

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Basic steps for calculating the SCCR of a control panel

4.2 SB4.3 – Adaptation of the available short-circuit current rating based on the peak let-through currents when

using current-limiting devices in the feeder circuit

Example 2

⇒ SCCR 50 kA since the breaking capacity of the circuit breaker is not lower than that of the

fuse.

The contactor and overload relays are protected by the fuse in the feeder circuit since 5 kA

(SCCR of contactor and overload relays) is > 3 kA (let-through value of the fuse).

Short-circuit current rating (SCCR) of industrial control panels

Reference Manual, 06/2013, A5E31896849002A/RS-AA/001