What is Voltage Optimization?
Voltage Optimization is the proven energy-saving technique of reducing and cleaning the electricity voltage supplied to a site, in order to:
- reduce power losses by eliminating excessive consumption.
- improve power quality in order to reduce wear and extend the life of electronic equipment.
When additional measures are taken such as balancing phase voltages, and filtering harmonics and transients from the supply, the process is known as Voltage Power Optimization, or VPO. When coupled with other smart grid power management technology, Voltage Power Optimisation gives the end-user the ability to manage and optimise their supply in order to immediately correct power quality problems from the grid, and does so with great efficiency. In the UK and Europe, the use of Voltage Power Optimization over the last five years has achieved average energy savings of around 13%. This effectiveness has contributed to making voltage optimization one of the fastest-growing energy saving techniques on the world market. Many major businesses (such as Hilton Hotels and Ikea), and Public Sector organisations (such as BC Hydro) use it as a direct energy conservation measure.
Voltage Optimization is especially well-suited to use in large facilities and factories, where it can immediately reduce power consumption and extend the life of equipment significantly.
How Voltage Optimization Corrects Power Quality Issues
Overvoltage is voltage supplied that is greater than the voltage at which equipment is designed to operate most effectively. It causes wasteful increases in energy consumed, and can significantly shorten the life of electronics – with no benefit whatsoever to their performance. The 16th edition of the Electricians Guide BS7671 states that aA 230V rated lamp used at 240 will achieve only 55% of its rated life” and that “a 230V linear appliance used on a 240V supply will take 4.3% more current and will consume almost 9% more energy.” Voltage optimization allows equipment to operate at its ideal voltage – and is a robust and safe technology that avoids the potential problems inherent in running full incoming power in-line through electro-mechanical devices.
Harmonics are current and voltage waveforms at a higher frequency than the fundamental 50Hz main supply and occur at multiples of the fundamental. They are caused by non-linear loads, which include types of power supplies for computer equipment, and many transformers. “Triplen” harmonics, which are odd multiples of the third harmonic, occur when phase voltages are unbalanced in a three phase power system, and accumulate in the neutral, causing wasteful current. If the total harmonic distortion, which is the level of harmonics, becomes too high, then damage can be done to to sensitive electronic equipment – and HV transformer efficiency can be lost. Electrical load efficiency can be enhanced by attenuating harmonics at the power source, or by preventing their initial generation.
Transients, also known as voltage spikes, are large, brief, and potentially harmful increases in voltage. They are caused by lightning, by the switching of large electrical loads such as motors, transformers and electrical drives, and by switching between power generation sources. Although they typically only last thousandths or millionths of a second, transients can devastate sensitive electronic systems, degrading components and shortening equipment life.
Phase voltage imbalance
Most medium to large industrial and commercial sites are supplied with 3-phase electricity, which is transmitted from the national grid in 120º phase intervals. Imbalance between the three phases causes problems somewhat similar to those of harmonics, for example heating in motors and existing wiring leading to wasteful energy consumption .
Effects of Voltage Optimization on Electrical Loads
Many assume that a reduced voltage simply results increased in current – and therefore remains unchanged. However, most sites have a variety of electrical loads that can benefit – with energy savings aggregating across a site in its entirety. The benefit to typical equipment at three phase sites is discussed below.
Three Phase AC Motors
Three phase AC induction motors are typical three phase loads and are employed in a variety of equipment including refrigeration, pumps, air conditioning, and conveyers. The effects of overvoltage and three phase imbalance on AC motors are commonly known: Overvoltage results in saturation of the motor’s iron core, wasting energy through eddy currents and increased hysteresis losses – as well as excess heat. This additional stress caused by overvoltage will decrease motor lifetime. Voltage optimization prevents overvoltage which saves energy and increases motor life, without affecting motor speed or reducing motor efficiency. This is especially apparent if the motor is to operate under a variety of loading conditions, as motor efficiency is reduced both in instances of overvoltage and less than full loading – both situations that can be managed through voltage optimization. And so substantial savings can be made through the direct consumption of less power – and also through extended equipment life.