Research and Analysis on the Performance of Differential Transformer Type Rod Position Detector

This study analyzes the causes of the rod position jump caused by the gourd-shaped waveform in induction voltage of the secondary A-code coil of the rod position detector, and proposes a solution to improve the performance of the rod position detector. Using a 1/2 calculation model, the secondary A-code coil was split and reconfigured. The study found that due to the placement of the secondary A-code coil #1 at the end of the primary coil, it is significantly affected by the large leakage flux at the primary coil end. This results in a relatively low induced voltage in the coil #1, which cannot effectively offset the induced voltage in the differentially connected secondary A-code coil #3. Consequently, a substantial residual voltage remains in the circuit at the zero-position voltage. To solve this problem, this paper proposes to increase the number of turns of the the secondary A-code coil #1 to compensate for the leakage flux at the primary coil end. This solution was verified through numerical calculation and prototype test. The results show that when the number of turns of secondary A-code coil #1 is more than 1.24 times, the small gourd-shaped waveform can be eliminated, the rod position jump caused by the small gourd-shaped is avoided, and the performance of the rod position detector is improved.