Manchester research on differential protection, synchronised using the global positioning system (GPS), has opened up a radically new approach to protection and integrity of electrical transmission networks. The research has led to updating of international technical guides and international standards. In the UK, National Grid has implemented policies based on the research, which will save about £0.5m per annum in substation upgrade costs. The market for GPS synchronised differential protection products is £400m pa globally. This figure represents the “insurance premium” against the avoided cost of a power system failure, estimated in a report on the North-East USA blackout to be $6bn in economic cost and 11 directly attributable deaths.