Copper facilitates better transformer efficiency and augmented loading capacity

Communicating smart transformers shall hold a key role in controlling the voltage of a transformer line and minimising the cost of expansion of lines
Rajesh Joshi, CEO, Tristar Technocrates

Rajesh Joshi, CEO, Tristar Technocrates talks about the requirement for timely maintenance of any distribution transformers and how to avert recurring failures. He discusses how the use of copper facilitates for better transformer efficiency for the same size and rating of transformer. This improved efficiency shall further be significant with augmented loading capacity on the transformer.

What are the reliability and energy efficiency issues that crop up in distribution transformers?
Reliability of distribution transformer which may cause early failures during its service life can be categorised in two ways depending on the manufacturing side and the utility side. In the manufacturing, because of competitive pricing, the designers are forced to compromise and ignore few of basic parameters like clearance, temperature rise gradients etc.

Owing to it, they end up using poor quality core, insulation, oil, and other materials, that deteriorate quickly, during service. Moreover, the end result we see is, loose core-coil assembly, improper fixing of CCA to tank and defective fitting of accessories etc.

Whereas, on the utility side, most of the distribution transformers are taken up for installation right from the stores without basic pre-commissioned tests. Ignoring the test can possibly lead to defect/breakages during the transportation.

Many times, either due to pressure of restoring the power supply or due to unavailability of appropriate connectors to O&M staff, the importance of terminations is compromised, that further contributes to intermittent overheating, absence of protective devices & incorrect earthing.

Few factors affecting the energy efficiency, handpicked by the utility companies are use of core material, with poor properties curve, and higher magnetising current causes unwanted load loss, use of lesser conductivity material, improper internal, external connections and terminations and under loading/overloading profile of the site where the transformer is installed.

No significant steps have been taken by the concerned authorities to carry preventive maintenance of distribution transformers. No mechanism seems to be in place to attend a leaking transformer or the transformer with pipe open at breather end. Changing the breather gel is a distant dream.

How is copper facilitating towards the efficiency of transformers?
It’s a globally known and accepted fact that copper is a superior and reliable conducting material. The use of copper conduct is relatively higher by 35 to 40 per cent than aluminium in transformer windings or in any other windings. Apparently, use of copper facilitates for better transformer efficiency for the same size and rating of transformer. This improved efficiency shall further be significant with augmented loading capacity on the transformer.

If there is a shortage of copper in a transformer, what would be the outcome?
Shortage of copper in transformer shall lead to compromised quality and quantity of supply. If there’s a shortage or unavailability of sufficient copper material, the designs can be modified with increase in core and lesser copper for a defined efficiency level.

In future, do you think any product would be replacing copper? If so why?
There do exist enough of materials that can replace copper in any transformer, like silver which has a much higher conductivity than the copper, but the cost and the mechanical strength remains a challenge. So, even with the availability of silver, the highest conductor, copper will still be considered best for efficient as well as reliable transformer winding conductor. To some extent, a mixture of copper silver alloy may be concept in the near future, for better efficiency aspect. However, the fact will remain that silver is rarer to be found on Earth, than copper. For other alloying options, the efficiency shall be compromised.

How do you view the opportunities of distribution transformers in smart city projects?
For impending smart city projects, besides availability, quality of power is also being considered as an imperative aspect. Transformers, being the heart of the distribution system and the costliest asset, has attracted the central attention in this “smart grid” concept.

IoT based monitoring system shall be the key for the utility companies, as it will help them formulate real-time actionable strategy by integration of sensors, data management and analysis. Communicating smart transformers shall hold a key role in controlling the voltage of a transformer line and minimising the cost of expansion of lines.

The smart transformers shall contain sensors for the following major parameters:

• Oil level monitoring (Sensed by : Magnetic float switch)
• Top & Bottom oil Temperature (Sensed by : RTD)
• Winding temperature (Sensed by : RTD)
• Phase wise Voltage, Line Current, Neutral Current, Load(active & reactive power), Power factor, frequency & other electrical parameters(Sensed by : Energy meter)
• Internal Pressure (Sensed by : PRV/Pressure relay)
• Humidity of surrounding air (Sensed by : Humidity sensor)
• Vibration sensor (Sensed by: Vibration switch/sensor)