Notes on the testing of static transformers

The paper describes the usual methods adopted in the commercial testing of static transformers. Emphasis is laid on the need for accuracy, and methods are suggested whereby it can be obtained. The drying-out of transformers, the determination of dryness, and the measurement of insulation resistance are discussed. The measurement of the iron loss and load loss is described, together with methods for obtaining greater accuracy. The measurement of form factor and its effect on the less measurements are dealt with; and methods for determining the ohmic resistance, also corrections for the same, are detailed. The loading of transformers for a full-load test, and the temperature-rise readings obtained on this test, are discussed. Over-potential and pressure testing are described, and the methods of measuring high voltages are detailed.