Choosing a Winding Resistance Meter for Transformer Diagnostics

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Distribution transformers are often subjected to vibration, overloading, electrical spikes and weathering. This can result in the degradation of the connections and the windings. It is a good idea to carry out preventive maintenance checks to catch problems that are just about to start. This can save you a lot of time, effort and money. Just imagine the hassle of repairing the whole electrical system because of a blown transformer. This could’ve been prevented if the problem was caught early.

Measuring winding resistance is a test carried out on transformers for preventive maintenance. This test helps determine if the connections are correct, 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 for a winding resistance tester, it is important to know the capabilities of the device. This allows you to get the most suitable tester for the needed application and get the best value for your money. You do not want to get a tester that is packed with a lot of features without being able to utilize most of them.

Raytech offers a wide selection of winding resistance meters that are accurate and reliable. Some of the popular testers Raytech offer are the WR14 and the WR50-12. These models provide high output current and automatic discharge and demagnetization for extra protection during diagnostics. Read on for a comparison of features that may help you decide on what model to get.

Raytech WR14 Winding Resistance Meter

The 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.

Product Features

  •        Touch screen UI
  •        Charge inductive loads up to 1500 Henry
  •        Data exchange through a USB drive
  •        Dual channels for resistance measurement and temperature
  •        15 Amperes output
  •        Variable test voltage from 0 to 30 volts
  •        Demagnetizing circuit
  •        Discharge indicator
  •        Emergency stop button 
  •        Built-in printer
  •        Internal storage that can store 10000 test results
  •        Can measure resistance from 0.00 Ohms up to 100 kiloOhms
  •        Battery operated
  •        USB and RS232 connectivity
  •        Included accessories

o   5-meter current and potential leads

o   Manual

o   5-meter jumper cable

o   Software for downloading data

Raytech WR50-12 ​Winding Resistance Meter

This winding resistance meter is pretty similar to the 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.

  •        Touch screen UI
  •        Charge inductive loads up to 1500 Henry
  •        Data exchange through a USB drive
  •        Dual channels for resistance measurement and temperature
  •        50 Amperes output
  •        Variable test voltage from 0 to 30 volts
  •        Demagnetizing circuit
  •        Discharge indicator
  •        Emergency stop button 
  •        Built-in printer
  •        Internal storage that can store 10000 test results
  •        Can measure resistance from 0.00 Ohms up to 100 kiloOhms
  •        Battery operated
  •        USB and RS232 connectivity
  •        Included accessories

o   10-meter current and potential leads

o   Manual

o   10-meter jumper cable

Protec can provide you with the equipment you need to carry out preventive maintenance tests. We offer low and high voltage test equipment to cater to your needs. Give us a call at 1-866-352-5550 to learn more about our equipment acquisition options.