Excessive supply voltages are quite common in South Africa. The histogram below represents a supply point in Sandton. The Average voltage is 245V, but voltages exceeding 250V are not uncommon.
The Powerstar® product which Tsebo Energy Solutions have the exclusive right to distribute in South Africa is a Voltage Optimisation Unit which reduces the energy demand of most electrical devices.
Resistive loads will draw a reduced current when a lower voltage is applied. In cases where the loads are controlled by thermostats or similar control systems, the load will simply stay on longer until the required energy has been consumed. In these instances, the energy consumed will be the same, but the demand will be reduced. In the case of electric motors, especially those that are not fully loaded, the overall efficiency of the motor will increase if the supply voltage is reduced to the nominal design voltage.
Different types of equipment will respond differently when supplied by a reduced voltage. In an average building, there will be a selection of plant that will consume less energy when the voltage is reduced.
All electrical devices will consume energy and dissipate it in the form of heat/sound/motion. Voltage Optimisation Units are no exception to this rule, they are however extremely efficient in design, and the additional losses introduced are offset by the very significant reduction in electricity demand from the load.