How to measure the resistance of transformer tap changer?
1) 1600kVA above transformer, each phase winding resistance difference should not be greater than the three-phase average value of 2%, no neutral points out of the winding, the difference between the line should not be greater than the three-phase average value of 1%.2) 1600kVA and below the transformer, the difference between the general is not greater than the three-phase average value of 4%, the line difference is generally no greater than 2% of the three-phase average.3) compared with the previous measurements of the same site, the change should not be greater than 2%.
TransformerThe DC resistance measurement project is a necessary project for handover and preventive testing. The DC resistance includes the transformer's high voltage side (ABC), the three-phase DC set and the low voltage side DC resistance. After the measurement, the three-phase balance coefficient must be calculated.
As the voltage level and capacity of the transformer are different, the materials used and the diameters are different, and different transformers and DC groups are different.Measuring transformer DC group using the instrument: now are using a special transformer, DC group test instrument, charging current is larger: 1A - 10A selection, charging time is short, resistance stability fast. Single and dual arm bridges are virtually useless.
