How to decide on Low impedance OR high impedance protection?

Low-impedance bus differential relays are so named because the differential relay current inputs have a low impedance to the flow of CT secondary current. This means that the low-impedance bus differential relays can share the CTs with other relays, meters, transducers, etc. The low- impedance bus differential scheme typically has one set of current inputs for each phase from every set of CTs in the

scheme.