Leakage Reactance Short Circuit Impedance （漏抗和短路阻抗）.pdf

Leakage Reactance Short Circuit Impedance Tests Leakage Reactance Measurement What is it? The measurement of the transformer impedance with the secondary winding short circuited by applying a voltage to the primary and measuring the corresponding current. Ohm鈥檚 Law: Z=V/I Why we do it? 鈥 Assess physical condition of the transformer (Geometry of Specimen) 鈥 Attempting to detect winding movement or deformation How we do it? 鈥 Using a single phase high current low voltage source 鈥 Measure voltage across and current through an individual winding Leakage Reactance Measurement 鈥 The measurement of the reactive component of the transformer impedance with the secondary winding shorted, voltage applied to the primary and measuring the corresponding current. 鈥 With the secondary shorted, current is drawn by the primary in response to the counter flux from the secondary in order to balance the voltage. 鈥 Measurements are sensitive to geometrical changes in the leakage flux path. When We Run the Test 鈥 Investigative Test 鈥 Responding to incident that questions the transformer鈥檚 health 鈥 Focused testing designed to detect specific problems 鈥 Focused on the geometric integrity of the transformer Other tests that perform similar evaluations 鈥 Capacitance test 鈥 General assess will not identify specifics 鈥 Frequency Response Analysis (SFRA) 鈥 The Short Circuit measurement will provide independent confirmation Leakage Flux definition Theory Flux due to the current in the primary winding, that does not link the secondary and the flux due to the current in the secondary winding that does not link the primary winding. Practical The flux that is not confined to the core for the entire length of it path. The flux which is present in the unit permeability space. What is Unit permeability space: It includ