Testing device for H.V. transformers - measures the transformation ratio error and the phase angle

摘要

The tester has on the h.v. side a voltage divider with a capacitor, adjustable in decades. A bridge cct. with a null detector is provided between the earthed ends of the two transformer windings and the junction point between the voltage divider two impedances. The transformer l.v. winding supplies through a low leakage transformer a first slide wire, and through a 90 deg. shifting stage (e.g. an air-core transformer) a second slide wire, whose wiper voltages are added to produce a compensation voltage for the bridge. The decadal adjustment means are provided at the low leakage transformer. The l.v. side impedance of the voltage divider is a decade adjustable resistance forming the input cct. of an integrating amplifier, and the low leakage transformer primary winding has tappings arranged in decades. A voltage divider with corresponding tappings is provided at the amplifier output. The bridge circuit is connected to its tapping, and one end of the voltage divider is connected to the tapping of the low leakage transformer primary.