Product category: Electromechanical Components
News Release from: Crydom International | Subject: Crydom solid state relays
Edited by the Electronicstalk Editorial Team on 29 October 2007
Relays meet short circuit standards
Crydom's approved ratings allow panel builders to establish the SCCR for the branch circuit where the relay is located without performing additional testing
Crydom has released the first solid state relays with UL-approved short-circuit current ratings (SCCR). These relays facilitate industrial control panel builders' efforts to comply with the new article 409 from NEC and the latest version of UL508A by providing them with pre-approved ratings for SSR/fuse combination.
This article was originally published on Electronicstalk on 29 October 2007 at 8.00am (UK)
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According to Dr Oscar Montero, from the Crydom Global Technical Centre, 'Standard 5kA SCCR on power devices prevents panel builders from offering panels with higher ratings'.
'Panels with a higher SCCR could be connected to electrical systems with different available currents bringing market advantages for panel builders'.
'However, establishing a higher SCCR may represent significant challenges and additional costs for panel builders'.
Crydom's approved ratings allow panel builders to establish the SCCR for the branch circuit where the relay is located without performing additional testing.
The ratings can be added directly to the manufacturer's procedure.
Hence, effectively reducing the time to market cycle for the panel and cost associated to compliance.
Crydom has obtained UL approval for SCCR by testing the combination SSR/Fuse under the 'umbrella fuse' requirement, allowing more flexibility to Crydom customers to mix and match SSR and fuses of different ratings.
'The tricky part is selecting the right fuse for not only the application but also for the desired SCCR rating for the combination'.
'It is understood that undersizing the fuse may compromise performance, while oversizing it may impact the safety of the panel, not to mention add unnecessary cost' Dr Montero said.
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