In this paper the authors present an application-layer reporting-rate regulation, or flow control, mechanism that enables reliable sensor data transport over nondeterministic communication networks in latency-critical applications such as protection. This enables the real-time characteristics of a system to be preserved during unfavorable telecommunication network conditions. The proposed is a novel mechanism to adjust the sensor data reporting-rate automatically at the application-layer to ensure data delivery as close to real-time as possible in latency-critical applications; thus mitigating the effect of buffering due to network-level flow control, particularly in the event of primary link failures. A case-study application of island detection by synchrophasor is presented along with a test-bed to prove the proposed mechanism. This uses a Wide Area Network simulator, configured with real bandwidth and latency data collected from a télécoms survey of the case-study area.