Distribution transformers: poised for a revival

Though the distribution transformer segment is facing challenges currently, revival of renewable energy and evolution of EV charging infrastructure are expected to fetch new opportunities in future. 

Distribution transformers constitute one of the most important segments of power distribution system. In India, the distribution transformer market is growing steadily, though there was a slowdown in the last one year due to the Covid-induced lockdown.

Demand trend

In the current market scenario, single-phase distribution transformers in 11 kV class from 5kVA to 25 kVA rating, has become a preferred choice in India, when the concept of LT-less distribution system got an attention, to bring the HT line as close to customer as possible to reduce the Line Loss and prevent theft. This is also popularly known as High Voltage Direct Supply (HVDS) system. Though some state utilities were already buying small rating 16, 25 and 40 kVA three-phase transformers for the same objective. Single-phase transformers are basically conceptualised for mounting on ‘single pole’ near the customer availing single phase 230 V AC supply mainly for domestic purpose. And for practical reasons somehow this could not be implemented in large scale. And so, the demand of single-phase transformer is slightly low in coming years. Three-phase distribution transformers of such small rating, one may call rural ratings, are installed in large numbers in last 10 years under various schemes mainly for agricultural connection and rural energy access. Currently, the demand is less. Some pending procurement due to Covid-19 lockdowns shall be done now. However, demand is expected to increase in the next 2-3 years as our per capita energy consumption starts rising based on economic prosperity and returning to normal post-pandemic. 

Dry-type vs oil-type 

The dry-type transformers are considered less hazardous due to the absence of mineral oil considered unfavourable to ensure electrical safety-related fire accidents. Hence, it provides an array of application ranging from residential building to small commercial complexes, particularly where the installation is indoors. While on the new technologies like ester oil-based distribution transformer, though proven as effective alternate to dry type abroad, it is yet to catch up here. Moreover, such technology is environmentally friendly. In India, due to the cost factor for dry type DT being as high as 1.6 to 1.8 times of mineral oil filled distribution transformers, high operating temperatures, inability to load higher, the noise levels etc, for same rating and efficiency, these are normally not preferred in distribution transformers of smaller kVA, except were mandated otherwise under electrical safety regulation. 

Intelligent features 

The intelligent transformers have smart sensors fitted, which collect data and combine them to provide powerful analytics and deep insight into operational or functional performance. These transformers are equipped with intelligent electronic devices and smart monitoring and diagnostics features as load regulation, efficiency, temperature rise, vibrations and noise. The relay devices with combined features to monitor oil and winding temperature, low oil level and gas collection are also being used for protection purposes. Upcoming submersible wireless robots can perform fast, safe and cost-effective internal inspection, which can be shared remotely with experts. Also, such transformers are capable of independently regulating voltage and allowing remote administration based on real-time feedback on power supply parameters. 

The transformer being the heart of electrical system, smart built-in features in transformers definitely help in improving the reliability, as well as the quality of supply in power distribution system. With added communication network devices based either on PLC, RF or GPRS as per geographical and network conditions, smart metering can be implemented. A smart feature enabled digital transformer provides the precise amount of power required and immediately responds to fluctuations in the power grid, acting as a voltage regulator. Therefore, this will meet the challenges due to massive growth in renewables-based power generation, distributed energy resources (DER), which is resulting in greater voltage fluctuations in the power distribution network.

Replacement of aging transformers 

This is a key area, where developing countries like India have lacked so far. We had been following the classical/ traditional approach of ignoring the distribution transformers until it fails. Given an official position of DT failure rate of 14-15 percent per annum, our DT fails every five to six years which is a matter of concern. Though in cash-starved position, utilities spend annually close to ₹8,000 crore in repairing DT and just putting back in service without even looking at post repair performance. In other words, the nation sacrifices efficiency adding to carbon emission further through our legacy assets many of which don’t even see the reasonable technical life that is at least 25 years as defined in national norms. Neither we have an official national standard for repairing DT that is much needed to ensure minimum good practices are observed in the whole process of repairing DT, often carried out by informal players as utility outsourced activity. The established players are not keen on this repair market that does not incentivise ‘Performance-based Repair’ but looks for low cost and encourage unhealthy competition. There has to be incentive penalty mechanism for DT repair business if we are looking for robust asset management of our key asset. In short, there was no defined policy as a whole.

Now since the mandatory BIS Certification with new and higher efficiency levels have been mandated, utilities have started replacing the old transformers, even much before end of life, at par with them. However, non-uniformity of specifications in different utilities exist though national harmonised standard is in place. Commoditisation of DT is far away though it can drive the cost down while ensuring desired performance. Essentially, and more so as per current financial state of the utilities after the pandemic situations, asset management became more vital factor. The utilities with lack of funds can now plan about methods for enhancement of reliability and improving the efficiency by replacing with better materials such as copper in installed distribution transformers at a lesser total cost of ownership.  

Market outlook in India 

The distribution transformer market in India is facing multiple challenges. The major purchaser, the state power utilities’ all major projects in distribution sectors are more or less complete two years ago and launch of new project and schemes are affected by Covid-19 pandemic and lockdown-related delays. The cashflow of financially constrained utilities does not give much room either unless government granted schemes are available. Yes, the new sector of renewable energy, being part of India’s clean energy transition drive, has enormous potential in the next 5-10 years. Along with solar energy, the EV charging infrastructure shall require a large number of distribution transformers. After the slowdown, the industrial sector andreal estate sector is also expected to grow rapidly now. The global positioning of China and other countries of western world is also raising hopes for Indian manufacturers, both quality and environmental conscious ones, to place themselves better in export market. 

Expertise shared by: Rajesh Joshi, CEO, Tristar Technocrates (Transformer Design Consultants)