1. What is SCCR?
SCCR is an abbreviation for Short-Circuit Current Rating, which refers to the short-circuit current rating and indicates the maximum current value that a device in each power circuit can withstand in a short circuit.
When exporting machinery to North America, the National Electrical Code (NEC) and NFPA79, the electrical safety standard for industrial machinery, require that the Short-Circuit Current Rating (SCCR) value be displayed on the industrial control panel.
2. When is SCCR required?
As described in Section 1, industrial machinery and industrial control panels (UL508, UL508A, etc.) mainly for North America are required to display the SCCR.
Additionally, there are descriptions of SCCR in national standards including SEMI S-22*1, the standard for semiconductor manufacturing equipment, the international standard IEC60204-1, and Japan's JIS standard (JIS B 9960-1). We believe that SCCR will be similarly required at a global level, including in North America.
*1: A standard established by SEMI (Semiconductor Equipment and Materials International), an international industry association for semiconductor and flat panel display (FPD) manufacturing equipment and material manufacturers, with the aim of unifying international industrial standards in the semiconductor industry.
3. About SCCR object right or wrong of our products
About SCCR object right or wrong of our products refer table 3.1
table 3.1
| item | Product | Object right or wrong |
|---|---|---|
| 1 | Power supply | Not applicable |
| 2 | EMI/EMC filter | Applicable |
Regarding the power supply, the main circuit is mainly composed of non-applicable parts (resistors, capacitors, coils) specified in UL508A*2. In addition, a transformer is mounted inside the power supply, and since the primary side is not directly connected to the power machine, we believe that it is the same as a transformer, which is non-applicable part specified in UL508A.
Noise filters are subject to SCCR in the UL508A standard (as of August 2020), so the deemed values specified in UL508A Table SB4.1 are applied, and some of our products undergo SCCR evaluation through a third-party application organization (UL). Detailed SCCR values for noise filters are summarized on the following page (Section 4)
*2: UL508A is a safety standard that specifies the design of industrial control panels.
4. SCCR noise filter compatibility
The deemed SCCR values (SCCR values that can be applied without testing) from UL508A Table SB4.1 and the SCCR values evaluated through a third-party application body (UL) are shown below.
<SCCR assumed value from UL508A Table SB4.1 (SCCR value applicable without testing)>
As stated in UL508A, if the noise filter is UL1283 or UL60939-3 certified, the SCCR value in Table SB4.1 can be applied as an assumed value.
Table 4.1 SCCR Deemed Values (SCCR values applicable without testing)
| item | EMI/EMC filter Rated Current [A] |
SCCR assumed value |
|---|---|---|
| 1 | Under 100A | 5kA |
| 2 | Over 100A | 10kA |
<SCCR value evaluated by a third-party application body (UL)>
In order to further increase the SCCR value, Cosel is conducting SCCR evaluations on some of its products through a third-party application organization (UL). The application is carried out by mounting a listed certified breaker in front of the noise filter.
Any listed certified breaker from any manufacturer can be used, but to satisfy the SCCR value, a listed certified breaker must be mounted in front of the noise filter.
*For requests for reports detailing the evaluation conditions, please contact us here.
Q&A: How to select a breaker
https://www.cosel.com/en/coselplus/technical/85
Q&A: How to select a fuse
https://www.cosel.com/en/coselplus/technical/84
