supply of surge protection device (spd)surge protection device (spd),supply of class b&c surge protection device (spd) type i & ii with visual indication and poten tial free contract to remote monitoring as per rdso spec no. rdso/spn/165/2012 version 3.0 or latest and iec standard 61643 for signals line 230 v ac application with handling lightning surges of 10/350 microseco nds and switching surges of 8/20 microseconds. one set consists of 3 nos of spd (two nos of b class (l n, n-e) and one no of c class (l-n) all enclosed in a box with kema or vde certified as per latest iec 61643-11- 2011 standard class b&c surge protection device required with three modules only [ warranty period: 1 2 months after the date of delivery ] ]