Optimising voltage to improve efficiency

Australia has a particular problem with overvoltage and voltage optimisation is a solution to reduce energy consumption and carbon emissions. This article explains how the various types of optimisation systems can deliver cost savings and reduce significant tonnes of CO₂.

Voltage optimisation is a technique that has a significant impact on energy consumption because it brings the voltage supplied by the grid in line with what is actually required, and reduces losses in electrical equipment. Voltage optimisation can help businesses reduce annual energy consumption by 12-15% or more.The statutory electricity supply range for Australia is 230 V +10% to -6%, which means that electricity suppliers are required to provide a voltage level that is between 253 and 216 V. Therefore, the supplier will distribute electricity at 253 V and the voltage decreases over distance. On average, is it received from the grid at 242 V.

Given that most electrical equipment manufactured for Australia is designed to work most efficiently at 220 to 230 V, any incoming power that is higher than this level is wasted energy and means companies are paying for power that is not required and not used.

Voltage optimisation works best on inductive loads - motors and lighting for example - and significant savings can be achieved on motors in particular, especially if these are not loaded at 100% of their capacity for 100% of the time. Voltage optimisation effectively reduces the voltage to an optimum level, whereby all the equipment operates correctly but consumes less power in the process. These systems should also offer improvement in power quality by balancing phase voltages, cancelling damaging harmonics and transients from the electricity supply and reducing the reactive power, hence improving power factor.

Overvoltage means that energy consumption is not only higher but, as a result, the life span of equipment is shortened. Installing a voltage optimisation unit leads to reduced maintenance costs as less demand is placed on electrical equipment.

There is nothing to be gained by operating equipment at a voltage higher than it was designed for; quite the contrary, as overvoltage will significantly reduce the life expectancy of most equipment.

Generally, voltage optimisers will deliver between 12-15% savings. However, the most efficient solutions can save up to 26% of total electricity consumption and related CO₂ emissions without compromising the supply to electrical equipment.

Other benefits of installing a quality voltage optimisation system are: helps protect against damaging transients (power spikes) of up to 25,000 V; lowers the operating temperature of motors; provides an improved power factor by up to 20%.

In addition, there are no moving parts and therefore zero maintenance on the unit itself.

Sites that have their own HV distribution transformer, such as supermarkets, data centres, hospitals, hotels, education facilities and retail outlets, are more likely to benefit from a system that ensures voltage is supplied to a site at a constant level regardless of the input instability.

This technology is recommended in these applications because when the grid voltage varies (often throughout the night as the load on the grid disappears), it is able to hold the site voltage at the optimum level and maintain a high level of savings.

The stabilised voltage output is a vital feature for sites with critical loads, secure data and important operations that require high levels of reliability and security.

Older transformers have high levels of standing losses and the majority of modern transformers used on commercial sites use cold rolled grain oriented steel (CRGO) within their core, which still provides significant losses for buildings in comparison to amorphous steel.

Businesses investigating this type of transformer should aim to achieve sustainability marks and high energy efficiency ratings through accreditations such as LEED (Leadership in Energy and Environmental Design) and BREEAM (Building Research Establishment Environmental Assessment Method).

Along with savings in energy efficiency, LEED/BREEAM also measure the characteristics of the products installed within a building and how much of a product can be recycled. A further important LEED/BREEAM measurement is energy monitoring. It is important for transformers to come with a real time monitoring and targeting system, which enables companies to monitor energy usage as well as target further energy reductions.

Conventional transformers generally utilise CRGO steel within their core. It is usually supplied by the producing mills in coil form and it has to be cut into ‘laminations’ that are then used to form a transformer core, which is an integral part of any transformer.

Amorphous metal contains ferromagnetic elements alloyed with a glass former. These materials have high magnetic susceptibility, with low coercivity and high electrical resistance. The high resistance leads to low losses when subjected to alternating magnetic fields. This results in transformers that use amorphous metal at its core, reducing standing losses, delivering greater efficiency and increasing savings.

To ensure optimum savings and performance, a comprehensive analysis of a site’s power conditions should be completed before installation. As each building is different, with its own unique infrastructure and specific load requirements, a voltage optimisation strategy should be customised to each site.

It is very importance to install a tailored voltage optimisation solution supplied by an experienced and reputable company. This will not only provide maximum energy savings and carbon reductions, but will also ensure that equipment will operate as efficiently as possible at all times, that the lifetime of equipment will be maximised, and that maintenance costs will be significantly reduced.

*Sam Czyczelis is General Manager of Powerstar Australia, a wholly owned subsidiary of EMSc (UK). The company has been manufacturing the voltage optimisation solution Powerstar at its headquarters in Yorkshire for over a decade.