Current transformers rated for 5 kA and above are the core sensing infrastructure of the AC power grid, and Jordan Taylor, known as The Electric Brit, has published a video explainer breaking down exactly how they work and why the engineering margins matter at that scale.
The video covers three distinct protection functions these CTs enable: over-current protection, over-voltage protection, and differential protection. That last one is critical. Differential protection detects current imbalances caused by leakage, internal winding failures, and unauthorized power taps. Core saturation degrades measurement accuracy, and the video explains how transformer selection and calibration become precision decisions, not afterthoughts.
Read the original Hackaday writeup and watch the video if you work with grid infrastructure, protection relays, or simply want to understand why a damaged CT winding can cascade into a tripped breaker. The gap between low-voltage CT theory and grid-scale implementation is where this content earns its runtime.
[READ ORIGINAL →]