36 energy Efficiency
Improving the efficiency of HV motors and generators Demand for replacement HV coils, to help improve the efficiency and operational life of HV motors and generators, is increasing. James Stevens explains what needs to be considered when designing and manufacturing diamond coils to meet these demands.
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he discussion around repairing or replacing High Voltage (HV) motors and generators has been on-going for many years. This is an in-depth subject, often influenced by factors such as whether a machine is known to be faulty, the end-user can plan an outage for repair or replacement of the machine(s), or whether the existing machine has particularly low efficiency, or if the machine is operating continuously making an efficiency-based ROI realistic amongst many other factors. As the industry strives to gain a clear understanding of the effect of repair vs replacement, the full carbon footprint of each option, and contribution to the circular economy should certainly be included in the overall picture. Much like the debate about whether running a ten-year-old car with reduced efficiency is a better environmental prospect than purchasing a new car and absorbing the carbon footprint of manufacturing and transporting it. In calculating this comparison, it is key to consider the efficiency of old vs new, as well as the carbon footprint of manufacturing vs repair. There is an option to improve the efficiency of HV motors and generators when repairing, and this subject is one that would benefit from further research. As a manufacturer of diamond coils, Preformed Windings is often approached by repair companies, whether OEM’s or independent repair facilities, to supply coils to rewind HV motors and generators. This repair ethos is typically driven by factors such as; the end-user has this machine on a frame and does not want to redesign to suit a new layout, or integration of equipment down or upstream of the machine in question. The lead time of a new machine could be longer than that of a repair to their existing equipment. New equipment could be perceived to be less durable as the material content may be reduced. Regardless of the reason, there are key steps that can be taken to improve the operational efficiency of the equipment being repaired along with contributing to the circular economy, and we are seeing increased
Quarter 4 2020
demand from the industry for HV coils that both improve efficiency and offer a longer life. It takes experience and knowledge to understand the influencing or limiting factors, therefore often coil manufacturers in the repair market supply like for like replacement coils, 2 rather than optimising designs to improve machine characteristics at little or no extra cost. There have been studies showing that typically the largest loss component of three-phase AC equipment is I2R losses. An effective way to reduce I2R losses in a diamond coil is to reduce the resistance of the coil, which can be done by reducing the length of the conductors or increasing the crosssectional area (CSA).
“There have been studies showing that typically the largest loss component of threephase AC equipment is I R losses.�
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