A current differential protection system for a multi-terminal power line includes a current sensor for sensing a current at a local terminal, a controller (80) for time synchronizing the local terminal and remote terminals, and a fault detection module (98) to detect a fault in the multi-terminal power line if a differential current exceeds a threshold value. The controller (80) includes a time measurement exchange module (94) for exchanging time stamp data with remote terminals, an upper range clock for exchanging time stamp data with remote terminals and a lower range clock for indexing the current at the local terminal. A first time period of the upper range clock is N times a second time period of the lower range clock where N is a number of multi-terminals. The controller (80) includes a clock offset calculation module for determining an average time offset based on time stamp data from remote terminals and the local terminal.