Socomec Zero phase current transformer

From Socomec: You need core balance transformers to install fault detection and locating units. These enclose the active conductors and highlight earth fault currents. Socomec core balance transformers meet measurement sensitivity needs and are suitable for ISOM Digiware locating systems. Closed (ΔIP, WR and TFR series) or split (ΔIP-R series), both types are suitable for all wiring configurations. The use of the ISOM T-15 adapter is required to connect the core balance transformers to ISOM Digiware F-60.

From Socomec: Residual core transformers, including the active conductors, establish the differential sum of the vector currents to detect leakage currents. Closed ∆IC series models, these core transformers are suitable for all wiring configurations in new and existing systems. Mounted on a DIN rail, plate or straight on the cable, these residual CTs adapt to any setup constraints for easier and faster wiring. You need core balance transformers to implement differential relay protective or signalling units.