تماشای ویدئو Surge and Overcurrent SHORTS UL 1077 vs. UL 489 – Phoenix Contact از آی-ویدئو
http://www.phoenixcontact.com/shorts
UL 1077 and UL 489 are two standards used to test overcurrent-protection devices. These products each have their own unique characteristics and use. This video explains some of these differences.