Basic steps for calculating the SCCR of a control panel
4.1 SB4.2 – Determining the short-circuit current ratings (SCCR) of individual power circuit components
Short-circuit current rating (SCCR) of industrial control panels
14 Reference Manual, 06/2013, A5E31896849002A/RS-AA/001
Basic: Assumed short-circuit current rating
For unmarked components, the assumed maximum short-circuit current rating in accordance
with Table SB4.1 (see extract) can be used for calculating the short-circuit current rating.
Figure 4-2 Table SB4.1: Assumed maximum short-circuit current rating for unmarked components
(extract)
Basic: Tested combination of devices according to UL508
To increase the short-circuit current rating of a device, an appropriate protective device must
be connected on the line side of it. Which protective device is suitable is stated in the
relevant UL test report of the device whose short-circuit current rating is to be increased.
Example: A 3RT2015 contactor has a default value of 5 kA according to its rating plate. The
UL test report states the protective devices with which the short-circuit current rating can be
increased.
Figure 4-3 Extract from the UL test report
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