A novel design of small size DCT with a double tuned sampling circuit

DCT (Differential Current Transformer) is an important part of RCD (Residual Current Device), which is used to detect the existence of residual current in the power line. To guarantee an adequate sensitivity and linearity at a low current, a certain volume of DCT is required and results in large size of RCD. However, a smaller and more compact structure of RCD is required by the current market. The large size of DCT becomes an obstacle for small size RCD development. We propose a novel design of small size DCT with a double tunable sampling circuit that can meet the required performance of sensitivity and linearity. A similar value of linearity and sensitivity comparable to the large size DCTs can be produced by the smaller size DCTs and our proposed sensing circuit.