Siemens UL 508A Manuel de référence - Page 23

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4.3

SB4.4 – SCCR calculation of the industrial control panel

The SCCR of the industrial control panel is calculated with limitation to the lowest value of a

component or a circuit according to SB4.2 or SB4.3.

Example

The first calculation is based on SB4.2 and looks as the individual SCCR values with which

the components are marked or that appear on the list of unmarked components.

Industrial control panel

The components listed under control circuit do not have to be included in the SCCR

calculation for the industrial control panel.

The individual SCCR values of the individual power circuit components are as follows:

No.

①

②

③

④

Both the contactor and the overload relay have an SCCR of 5 kA at 480 V. If no further

information is available, this industrial control panel would be marked with an SCCR of 5 kA

at 480 V AC.

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

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

4.3 SB4.4 – SCCR calculation of the industrial control panel

Power circuit

Circuit breaker

Contactor

Overload relays

Fuses on the primary side of the control

transformer

Basic steps for calculating the SCCR of a control panel

Components

No.

Power circuit

①

Circuit breaker

②

Contactor

③

Overload relays

④

Fuses on the primary side of the

control transformer

No.

Control circuit

⑤

Control transformer

⑥

Control relay

⑦

Terminal blocks

⑧

Display lamp

⑨

HAND-OFF-AUTO selector switch

SCCR at 480 V

25 kA

5 kA

200 kA