Surge protective device surge testing: Noise detection and reduction

The members and contributors of the UL 1449 Standards Technical Panel (STP) have identified an opportunity for improving how noise is recorded and measured during the application of surges to surge protective devices (SPDs). Further, the group has investigated how noise should be considered when determining the measured limiting voltages (MLVs) - used to determine the voltage protection ratings (VPRs) - and surge currents impressed through the SPD during testing. A large variation of results from various manufacturer´s and Nationally Recognized Testing Laboratories (NRTLs) has been reported when determining VPRs. Noise has been suspected as a contributor to many of these variations. The UL 1449 STP Taskforce on Noise was formed to further investigate the issues related to measured noise and recommend changes to the existing UL 1449 standard and provide input to other standards development organizations.