Sensor systems reduces explosion risk of distribution transformers

Jon Lawson

There are 13 million distribution transformers that are key components of our electricity infrastructure. Currently, utilities have no cost-effective way to be alerted to a failure that can have a monumental impact not just on business continuity, but on the safety of utility employees and the population of surrounding communities. A recently launched system is setting out to create a paradign shift that greatly improves the current status quo.

The new product will cost up to 80% less and is three times smaller than existing hydrogen monitoring systems, opening the door to monitoring the 13 million transformers under streets, in neighbourhoods, industrial sites, wind farms and trains. ABB and other industry experts are testing prototypes of the system.

Its maker, H2scan, believes that its Gen 5 System is a “first of its kind” hydrogen sensor package that offers the high accuracy, small size and low cost needed to help utilities monitor and protect their distribution transformers.

Electronics for the system are consolidated onto a 4.7 x 4.7 1.2-million-transistor, application specific integrated circuit (ASIC). The ASIC, combined with three small 1 by 3in flex boards, allows the firm to develop a sensor package that weighs 1 pound, is 5.9in long and 1.6in wide. The ASIC and small flex boards drives down the cost of the device in large volumes by 80%, allowing the company to sell the Gen 5 System package at a price that is cost effective for distribution transformers.

H2scan works with OEMs including ABB, other transformer manufacturers and transformer equipment providers to sell its sub-assembly sensors and fully packaged products to end customers. Initial interest in the new system has been very high from some of the largest transformer manufacturers in the world.

“Power transformers are the most expensive and strategic components of any power system and the new small Gen 5 System acts as an early warning device that can alert the power utility to the health of the transformer,” said Dennis Reid, president, CEO and founder of H2scan. “Demand for electricity is growing and utilities sometimes have to overload these transformers by up to 300%. With our new system, utilities can better manage these valuable assets, keep their customers safe and keep the transformers in service for a longer time. ASIC technology can be extended to other sensor applications and we will be delivering some of these products in 2019.”

High accuracy

The Gen 5 System is designed for transformers immersed in oil, which are cooled and insulated using mineral, vegetable, or silicon oil. The sensor can be inserted through any port on the transformer, directly into the transformer oil where it takes measurements of hydrogen gas levels.

The sensor head uses the firm’s proven core sensor technology, which uses the interaction of hydrogen with palladium and a proprietary coating. This enables continuous, maintenance-free operation in harsh, contaminant environments. The platform is designed to accommodate other sensors that could be integrated in the existing package using H2scan’s flex circuit.  

The new sensor offers real-time, or step-change monitoring to report hydrogen levels as they fluctuate. Its high accuracy sensor head can track hydrogen levels in the transformer oil from 25 ppm to 5,000 ppm. This range is ideal for smaller transformers where power overloads can cause higher temperatures which drive up hydrogen levels more quickly.
The system is calibrated once while in production and then needs no maintenance or re-calibration for up to 10 years.

How oil-infused transformers fail

Hydrogen is a major fault gas observed in oil-filled transformers. Timely detection of a change in hydrogen concentration is critical in monitoring transformer health and extending asset life. Because distribution transformers are in populated areas, explosions can cause significant property damage and have the potential for loss of life.
In addition to monitoring distribution transformers, the Gen 5 System can also serve other currently unmonitored distribution transformers, including those used on wind farms, trains, and buses. 

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