Distribution transformers are often subjected to vibration, overloading, electrical spikes and weathering, resulting in the degradation of the connections and the windings. Preventive maintenance checks are a good way to detect problems early.
Measuring winding resistance is a test carried out on transformers for preventive maintenance. This test helps determine if the connections are correct and there are no severe mismatches or opens on the windings. Measuring winding resistance also gives information for calculating the I²R component of conductor losses and the temperature of the windings at the end of a temperature test cycle.
In earlier years, measuring winding resistance needed a lot of separate equipment like galvanometers, ammeters, slidewire adjustments, batteries and switches. This can be very complicated and may take a while. With the advancement in testing equipment technology, testing time has been greatly reduced and measurements made easier. A lot of the winding resistance meters on the market today are microprocessor based to ensure accuracy and allow automated tests.
When choosing a winding resistance tester it is important to get the most suitable tester for the needed application, and to know the capabilities of the device
Protec offers a wide selection of Raytech winding resistance meters that are accurate and reliable, providing high output current, automatic discharge and demagnetization for extra protection during diagnostics.
The Raytech WR14 offers 2 independent channels for measuring resistance and can charge inductive loads up to 1500 Henry. It also features a heavy-duty safety circuit and a fast discharge unit for protection. This tester offers the basic functions needed for testing transformers in commercial and industrial facilities.
This winding resistance meter is pretty similar to the Raytech WR14 but offers a higher output current and longer test leads. This tester is ideal for testing large transformers that need a higher test current. The WR50-12 also allows PC connectivity for transferring data to a computer.