Technical library

Gain insight into the different types of oil testing methods, including oil dielectric breakdown testing moisture content testing. This guide covers best practices for oil testing, the correct equipment to use, and the different IEEE/IEC standards to adhere to when testing.

This case study has been generously supplied by the Hitachi Energy Service group in Sweden. A 22 MVA, 10.5 kV/276 V (voltage regulation from 336 to 216 V), Diii furnace transformer, operating in heavy use for many years at a steel melting plant in Europe was subjected to a complete series of tests after a sudden failure during operation. The service contractor evaluated the electrical and dielectric condition of this transformer. During service, this type of transformer has its secondary winding connected externally in a Delta configuration through a high current bridge.

Software update for 'A' models

When unexpected results are experienced in testing the dielectric breakdown of oil samples the cause can often be traced to insufficient attention to one or more of the following key elements of vessel preparation.

Virtual reality has been around for more than two decades. What started as a feature of computer games has become the norm in many industries, delivering benefits that include reduced costs, increased reliability, and better efficiency. In the power industry, early adopters of virtual reality are not only enjoying these benefits; they are also finding that it helps them continue carrying out a whole range of tasks despite the travel bans and social distancing imposed by the ongoing pandemic. This article describes how tests of relay protection are performed virtually with the SMRT digital twin and what benefits it gives.

A new transformer was tested in the field using Megger’s DELTA4000. This is what was found...

A 1978 vintage, 20 MVA, 69/13.09 kV, Dyn1 transformer, operating for a major North American utility, was taken out of service to repair a pump in the cooling system. The technical maintenance team completed the required repairs and conducted a complete protocol of routine commissioning tests, including a 10 kV line frequency (LF) power factor (PF) test.

Measurement of the outer limits of the operating mechanism is required by international standards such IEEE C37 and as IEC 62271, when certifying a circuit breaker (CB). Some of those tests are valuable to repeat in field tests, obviously to ensure that the CB fulfil its design specification, but those tests and some additional tests in similar spirit can also disclose potential future problems. The most common is to vary the auxiliary voltage but it could also be other energy resources for example hydraulic and pneumatic pressure. This application note will focus of the auxiliary voltage, what the standard requires, sort out the terminology and what tests that are valuable to repeat in field tests.

Electric power transmission and distribution systems are vital for modern life. And, since the electricity these systems provide is essential, then these systems are essential too. One of the less celebrated components of these systems is the humble surge arrester. These arresters serve the important job of keeping the electric supply smooth and steady. As such, these devices must be tested regularly as part of a maintenance program.This application note looks at what a surge arrestor is, the test procedures of insulation resistance testers, as well as present test results and recommendations.

Software downloads for E-Tray products including Smart-Thump, EZ-Thump, EZ-Restore Overdrive and T3090.