The major challenge in transformer and reactor loss measurements is the fact that the losses are small. This means that active power needs to be measured at low power factors - that is, a phase angle between voltage and current close to 90°. These power factors go down to 0.01 for power transformers, and down to 0.001 for reactors.

The major challenge in transformer and reactor loss measurements is the fact that the losses are small. This means that active power needs to be measured at low power factors (that is: a phase angle between voltage and current close to 90°). These power factors go down to 0.01 for power transformers and down to 0.001 for reactors.

The aim of this work is to design and develop advanced industrial loss measurement systems (LMS) for loss measurement of power transformers of shunt reactors, at voltages and currents up to at least 230 kV and 2000 A respectively.

To measure these losses with an uncertainty of 5 %, accuracies of 0.0005 W/VA (500 μW/VA) and 0.00005 W/VA (50 μW/VA) respectively need to be achieved. This requires specialised measurement systems with extremely high phase accuracy to be used in the far-from-ideal electromagnetic circumstances of the manufacturers’ test facilities. For reactors this extreme phase accuracy has to be realised in measurements at fully operational voltages.

It was first necessary determine the requirements of future advanced industrial LMS systems based on requirements from the Ecodesign Directive, requirements expressed in present CENELEC, IEC and IEEE written standards, and requirements indicated by power transformer and reactor manufacturers. Two prototypes of improved LMS voltage channels were then developed with accuracies down to 40 μV/V in ratio and 30 mrad in phase displacement at voltages up to 230 kV.

For more information, see the project webpage >>