Transformer Ratio Meters

Handheld Turns Ratio & Winding Resistance Tester TWR-H - Amperis sl

TWR-H is a handheld, battery operated, fully automatic test set specially designed for turns ratio, phase shift, excitation current and winding resistance measurements of transformers. It can also perform demagnetization of these transformers. Transformer turns ratio is determined by applying AC voltage across high voltage winding, accurately measuring AC voltage across the corresponding unloaded transformer winding, and then displaying the ratio of these voltages. User can enter a transformer’s nameplate voltages, so that turns ratio deviation can be calculated. This feature eliminates any error otherwise caused by an operator’s manual calculation. TWR-H compares measured turns ratio with the nameplate ratio and prints out the % of error for each test. Transformer winding resistance is determined by injecting DC current through a winding, accurately measuring DC voltage across the winding, and then calculating resistance as the ratio of voltage and current. The device generates true DC ripple-free currents. Both the injection of the current and the discharge of energy from transformer magnetic circuit are automatically regulated.