... features of high efficiency, no wave distortion,reliable performance, working continually for long time, besides, SVC voltage stabilizer is ... Short circuit protection LED indicators to show status of working,unusual and delaying Selectable delay time Build-in transformer: ... (PCS) 2772 40GP(PCS) 5988pcs54m3 5676pcs(22T) 4.Working Principle: High Accuracy Full-automatic AC voltage Stabilizer SVC-500VA