Sweep Frequency Response Analysis Makes Transformer Maintenance Easy and Saves Time

Doble M5200 Sweep Frequency Response AnalyzerTransformers can sometimes experience significant physical stresses whenever they are moved from one location to another, such as when they are initially shipped from the manufacturer. Once they have been placed into service transformers can also experience tremendous stresses related to being in the path of fault currents when something goes wrong in the electrical system. The combination of mechanical and electrical stress can cause the transformer to prematurely fail. Symptoms may not be obvious until the damage is already extensive. Performing sweep frequency response tests can be used as an early identifier problems that occur as a result of physical changes within the transformer.

The Advantages of Sweep Frequency Response Analysis in Transformer Testing

Doble M5400 Sweep Frequency Response AnalyzerSweep Frequency Response Analysis (SFRA) is an electrical testing method which identifies changes to the internal workings of a transformer.  The transformer is an electrical filter that has a specific response to each independent input frequency. The test equipment is used to apply a test voltage to a transformer over a range of frequencies. 

The output of the transformer is then monitored in relation to its corresponding input frequency.  The results, when graphed, make up a signature response, much like a unique fingerprint. The initial SFRA test will then become a baseline for comparison when future tests are performed.  When these signatures do not match the baseline signature, something has changed internal to the transformer and merits further investigation.   

To Test Delta or Wye Transformers Consider Renting a Vanguard TRM-403

 Vanguard TRM-403 Transformer Resistance Meter Transformer configuration designations like “Delta” and “Wye” originate from the way the windings are connected inside the transformer. These connections determine the way the transformer will perform, and they also determine the methods of calculation required for properly applying a given transformer.

For Voltage Transformer Testing Rely on the Megger MRCT from Protec

Megger MRCT Relay and Current Transformer Test SetThe Megger MRCT Relay and Current Transformer Test Set has additional features that allow the tester to be configured to test voltage transformers, measure ratio errors and phase angles as well as the secondary winding resistance of inductive voltage transformers.  

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With the Coupling Capacitor Voltage Transformer (CCVT) Testing Option, the MRCT can measure the CCVT ratio and phase error.  It can also be configured to perform the excitation test on current transformers using DC voltage, allowing the testing of knee points on current transformers up to 30 kV.