The rotating machine and Transformers are permanently prone to vibrations. Therefore, some problems or defects may occur due to poor design, assembly, overload, poor maintenance, even poor environment around the transformer during operation.
Transformer resistance measurement is an image of the copper length of a given winding, and the quality of the contacts, present on the electrical circuit. On a three-phase transformer, the resistances between similar phases must be relatively identical.
There is usually a tap changer built into the power transformers. These taps allow to increased or decreased the turns number in the main winding of the transformer. These taps changes will be also checked during the winding resistance test.
Measurement of the transformer winding resistance is performed as a test type as well as a routine test to calculate the 𝑅.𝐼2 losses and the winding’s temperature at the end of a temperature rise test.
The purpose of this test is to check the significant differences between windings. Tests can be done also in the field to ensure the safety of the transformer design, to verify loose connections, broken conductor wires, high contact resistance in Tap Changers, high-voltage cables and bushings… etc.
WinRes-20 is a Digital Winding Resistance meter and Transformer Winding Analyser designed by advanced engineering technology to measure the DC resistance values of transformer windings. WinRes-20 can measure current, voltage, power transformer windings and shunt resistors. Applying up to 20 A DC allows WinRes-20 to measure the winding resistance of transformers quick and precise.
The smart design of WinRes-20 makes more apparent to determine the conclusion of measurements automatically according to users’ decision. WinRes-20 can measure two resistance values concurrently by its two voltage measurement channels. Users can prefer test two primary or two secondary or one primary and one secondary winding according to the transformer configuration.
Beginning from 0.01 μΩ resistances, WinRes-20 can measure up to 100,000 Ω resistance. WinRes-20 discharges the measured circuit after each test. For inductive load WinRes-20 can demagnetise the load. The temperature measurement input enables one to connect an optional sensor to WinRes-20 and perform temperature correction automatically.