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TTRU3 Factory ratio testing of power transformer
Transformer equipment manufacturers (OEMs) have a critical need to measure true ratio, as they must confirm proper manufacture of their transformers during construction and final assembly. Improper construction has consequences of higher cost, late delivery, and poor quality. The ability of a ratio instrument to be used for all steps involved makes it a practical valueto OEMs because only one instrument is purchased and used throughout each stage. Only the most reliable and accurate instruments make it to the factory floor. Winding stack under constructionre used: Art Mandigo Winding Service.
Published: 3 August 2020
Testing frequency relays with SVERKER900 considering the IEC 60255-181 standard
This application note is more than a description of how to use SVERKER 900 for testing frequency relays. It also wantsto spread the knowledge about IEC standardization in relay protection. Many engineers often associate theIEC series of protection standards IEC 60255-1xx1to relay type testing, and believe that they do not need to have competence about this series of standards. This is a misunderstanding: many of the concepts, definitions and test procedures described in thestandards are there to be used in relay technique, no matter if the role is relay manufacturer, user, or commissioning / maintenance testing engineer (, ).
Published: 30 July 2020
DLRO2: long test lead test mode
When measuring very low resistance the four-wire test method has for many years been the standard method. The main advantage being that it simply and easily removes the resistance of the test leads from the measurement. However, what happens when those test leads need to be verylong?
Published: 27 July 2020
DLRO2: new difference meter
Introducing the first low resistance ohmmeter to feature a difference meter, a device that turns changes in resistance into a moving pointer and percentage change. When testing multiple similar connections, it makes it easy to spot those small increases in resistance that eventually turn into major faults.
Published: 27 July 2020
Transformer winding resistance measurement: field challenges
Megger’s article “Transformer Winding Resistance Measurement: Field Challenges” was presented at the 2020 NETA PowerTest Conference in Chicago, Il. This article takes an in-depth look at the lesser known facts associated with the DC winding resistance (WR) measurements, diving deeper into topics such as selection of the correct test current, and the importance of compliance voltage during the test. Phenomena as core saturation, current stabilization, the influence of winding inductance on readings, and the effect of temperature, are also explained.
Published: 12 June 2020
Introduction to thermal imaging
While spot infrared thermometers present only a single temperature at a single spot, Thermal Imaging Cameras give you the whole picture. Thermal imaging is the most effective method for finding problems or potential problems in a variety of applications across many fields.Thermal imagers allow users to measure temperature in applications where conventional sensors cannot be employed. Specifically, in cases dealing with moving objects (i.e., rollers, moving machinery, or a conveyor belt), or where non-contact measurements are required because of contamination or hazardous reasons (such as high voltage), where distances are too great, or where the temperatures to be measured are too high for thermocouples or other contact sensors. The thermal imagers provide an image, which shows the temperature difference of the object being measured. Hot spots can be seen immediately versus traditional infrared guns, which average the area being measured.
Published: 10 June 2020