Assets in a substation represent a large investment, and their condition and continued reliability is essential. Testing assets in a substation has long required the use of significant resources in manpower and time to obtain reliable and comprehensive results while ensuring the maximum safety of the workforce.

OMICRON’s new approach to substation asset testing is proving that efficiency gains, without compromising safety and accurate results, are not only possible, but ensured.

The challenges of substation asset testing

Power transformers are widely considered the most crucial components in electrical transmission and distribution networks. Due to aging of transformer fleets in the field, regular diagnostic testing and condition assessment becomes increasingly necessary.

Maryam Khallaghi, OMICRON’s Regional Manager for Australia and the Pacific, says that this can represent a big challenge for businesses.

“Transformer designs can be very complex and measuring a variety of different parameters can be a time and cost intensive job. When performing different diagnostic tests, multiple devices and a frequent change of test leads are required. Individual phase measurements and multiple tap changer positions further increase the testing effort and outage time.

“On average, an entire working day needs to be scheduled for the full range of routine tests, usually making it the most time-consuming asset to test in the substation. We realised that solving these problems would require a special solution.”

Innovative solutions

In 2017, OMICRON released the TESTRANO 600, a highly portable, three-phase test system providing all common tests on power transformers.

Its three powerful amplifiers keep testing time to a minimum, while delivering the highest measurement accuracy on the market. Intelligent algorithms ensure fully automated testing on all three phases simultaneously making testing three times faster than using single-phase devices.

Florian Predl, Primary Application Engineer at OMICRON Australia, says TESTRANO 600’s simple connection concept enables its users to perform multiple tests using the same test set-up.

“This not only reduces the physical rewiring effort, but also further reduces overall testing time and increases safety for the operator.”

At the same time, an on-load tap changer (OLTC) can be fully controlled by the test set. This allows for a sequence of measurements to be executed with just the push of a single button.

Field testing

A practical test case, provided by Protección Control y Medición (PCM), a leading service provider in Guatemala, illustrates TESTRANO 600’s effectiveness.

Manuel Matinez, Electrical Test Engineer with PCM, described how his team was able to test eleven transformers in one day. “We started testing at 7am and had to test power transformers with 10MVA and 22kV including the de-energised tap changes (DETC). Numerous parameters were measured such as power factor, capacitance, short-circuit impedance, excitation currents, turns ratio and DC winding resistance.

“In between we also had to demagnetize the transformers – the effort for which was minimal given that no rewiring was necessary.

“We were impressed with the TESTRANO’s performance – by 4.30pm, only seven hours later, we were finished testing and all eleven transformers were ready to be reconnected to the grid.”

“These are exactly the kind of results we want our customers to be able to achieve,” Maryam Khallaghi says. “Reaching this new benchmark in reduced time and effort coupled with increased accuracy and safety means asset owners, and those that ensure their reliability, can make more informed maintenance decisions, more often.”

OMICRON has optimised testing solutions for power transformers, instrument transformers and circuit breakers, helping asset owners achieve minimum outage time with maximum diagnostic output and safety.

This partner content is brought to you by OMICRON. For more information, visit

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