Sweep Frequency Response Analysis Makes Transformer Maintenance Easy and Saves Time

Posted by Protec Tech Team on

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.

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SFRA testing is a very practical way to find developing problems in transformers.  It allows technicians to identify problems without untanking a transformer, and often can localize the problem to a specific area of the transformer (ie. core, windings, contacts and connections). 

 

The signature of a transformer's frequency response is defined in the electrical RLC filter that is representative of its components and their relationship to one another.  Electrical signals will resonate at certain frequencies in response to the frequency of an applied signal. By applying a range of frequencies, those specific points of resonance can be identified in addition to the transformer's characteristic response to the entire range of frequencies. The frequency response is plotted against the applied signal and the graphical representation of this relationship becomes something of a baseline signature of the transformer.  This identifying signature the becomes standard which all subsequent tests will be compared; kind of like a fingerprint.

 

An initial test is often performed at that factory prior to a transformer being shipped to the customer or when the transformer is first placed into service. This information is useful in identifying when changes have occurred within the transformer and further investigation might be advisable in order to protect the investment and avoid costly outages. 

 

Sweep Frequency Response Analysis is a simple and proven technique for detecting transformer problems. This test method is a well accepted method throughout the industry for identifying when changes have occurred inside of a transformer and is included in IEEE standards such as C57.152 for Field Testing Of Fluid Filled Power Transformers.

 

Some of the commercially available SFRA test sets on the market today include the Doble M5200 Sweep Frequency Response Analyzer and Doble M5400 Sweep Frequency Response Analyzer. They provide a non-intrusive way of identifying problems in transformers. Here is a short comparison of their features to help you determine which model suits you best.

 

The Doble M5200 Sweep Frequency Response Analyzer can help you diagnose transformer problems early and prevent expensive equipment failures. It has a wide band frequency measurement capability which makes it suitable for testing various kinds of transformers.

Features

  •        1 channel excitation source at 50 Ohms impedance
  •        20 Volts peak-to-peak excitation voltage output
  •        2 measurement channels
  •        10 Hz to 25 MHz frequency range
  •        Simultaneous sampling at 100 MS/s sampling rate
  •        PC connectivity through USB or LAN connection
  •        1000 points up to 1800 points
  •        1.2% Logarithmic point spacing
  •        >90 dB dynamic range
  •        ±1 dB to -80 dB repeatability
  •        <10% of active frequency IF bandwidth
  •        Frequency vs. Magnitude plotting
  •        Difference, Cross-Correlation and Sub-band analysis
  •        Short circuit protection
  •        9 lbs
  •        2-year calibration interval

 

Doble M5400 Sweep Frequency Response Analyzer

If you need a rugged SFRA with a longer calibration interval, the M5400 is the best choice. With a 3-year calibration interval, you can be confident that the device is highly accurate for a long time.

Features

  •        1 channel excitation source at 50 Ohms impedance
  •        20 Volts peak-to-peak excitation voltage output
  •        2 measurement channels
  •        10 Hz to 25 MHz frequency range
  •        Simultaneous sampling at 100 MS/s sampling rate
  •        PC connectivity through USB, Serial or LAN connection
  •        1000 points up to 1800 points
  •        1.2% Logarithmic point spacing
  •        >90 dB dynamic range
  •        ±1 dB to -80 dB repeatability
  •        <10% of active frequency IF bandwidth
  •        Frequency vs. Magnitude plotting
  •        Difference, Cross-Correlation and Sub-band analysis
  •        Short circuit protection
  •        13.1 lbs
  •        3-year calibration interval

 

Don't wait for problems to develop before taking action. Add SFRA to your arsenal of tools to combat transformer problems in your testing and maintenance program today. You can save time, effort and money by preventing unexpected failures.

 

This electrical test equipment is available for rent, lease, or purchase from Protec Equipment Resources. We are here to help you with your testing equipment needs.

Wherever the job takes you (and the equipment), with Protec's multiple locations, we always ship from the office closest to your desired drop location (if the electrical test equipment you need is in-stock at that location), and the equipment can be returned to the nearest office.

We always consider ALL shipping options in order to save you the most time and money.

Also, if you happen to be close to one of our many office locations, walk-ins are always welcome!

Rely on the Electrical Test Equipment Rental Experts, we are there when and where you need us.

 

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Editor’s Note: This post was originally published MO/YR and has been updated freshness, accuracy and comprehensiveness.

Topics: Doble, Transformer

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