The National Electrical Manufacturers Association has published a new white paper, “New UL Variable Frequency Drive Standard and Its Effects on Unit Short Circuit Rating,” which focuses on the impact of the UL adoption of IEC standard 61800-5-1 on safety requirements for adjustable speed drives with respect to certification of these devices. Specifically, it addresses changes in the evaluation of short circuit ratings assigned by the drive manufacturer.
The white paper was developed by the NEMA Industrial Automation Control Products and Systems Section (1IS) Subcommittee on Adjustable Speed Drives (SC7). It provides clarification to prevent attempts to apply non-relevant requirements to NEMA member products.
According to NEMA SC7 Chairman Dan Stewart, “As the drives industry transitions from UL 508C to UL 61800-5-1, integrators and end users may notice changes in drive SCCR’s (Short Circuit Current Ratings), recommended branch circuit and overcurrent protection devices, and/or requirements for supplementary enclosures for some drives. This white paper provides relevant background information.”
“New UL Variable Frequency Drive Standard and Its Effects on Unit Short Circuit Rating” may be downloaded at no cost on the NEMA website.