Considering Voltage Management to Help Cut Bills?


Voltage management comes in many technologies and is just one element of improving energy efficiency but, if considering voltage management to help cut electricity bills, quite often one of the lowest cost options gets overlooked and you may already have the equipment to achieve a voltage reduction to site in place.

The fundamental principle behind all voltage management is to lower the voltage level of the incoming supply.

If your site's electrical supply is metered at high voltage and you own the high to low voltage transformer(s) the option to ‘tap down’ the transformer could be the difference between installing expensive additional equipment opposed to utilising what you already have.

Typically these transformers have tap changers that allow manual adjustment of the voltage ratio, thereby controlling the site voltage. Older units typically offer a range of ±5% in increments of 2.5% whereas newer units offer a range of +5 -7.5%, again in increments of 2.5%.

Older transformers, wound to 433 / 240Volts on the secondary side, would have a nominal setting to tap 3. Here you have 2 available lower settings - adjusting by 1 tap would reduce the voltage by 2.5% (approx. 6 Volts) and lowering by the further tap would reduce the voltage by a further 2.5% (approx. 6 Volts). Occasionally these units may have been set above their nominal setting meaning an even higher voltage to site but giving even more scope for a reduction in the sites voltage.

Historically the UK’s supply voltage was higher than is now necessary due to various directives and consequently there are still lots of voltage dependent equipment currently operating at above its nominal required voltage, leading to consumption of more power. Voltage dependent equipment is classed as equipment unable to maintain a fixed voltage input and, as a rule of thumb, each percent over in supply voltage results in a 2% increase in power demand in these types of installations.

There are considerations to take into account and understanding your load is essential. Electrical equipment is designed to work within specific voltage ranges; more modern equipment is designed to maintain a fixed input voltage regardless of the supply voltage, opposite to the voltage dependant equipment mentioned previously. Quite often there is a mixture of these loads and it is essential that the supply voltage remains appropriate to cater for both.

Another consideration would be your current transformers tap setting in relation to sites supply voltage. If you have no movement left to reduce voltage any further but equipment capable of operating at lower voltages, then an option would be to replace your transformer for a modern more energy efficient equivalent. Thus giving greater voltage management options along with cutting typical iron and copper transformer losses introducing even greater savings.

For more information please see our Factsheets page or alternatively give us a call and one of our engineers will happily talk things through in more detail with you.