AUTOMATIC VOLTAGE OPTIMIZERS
IT’S TIME TO SAVE
By means of potentiometers the OPTIMAL OPERATINg VOLTAgE can be set according to the peculiar features of the connected loads. The minimum stabilised voltage is 207V.
The dwindling fossil fuel reserves, the need to reduce carbon dioxide emissions and lower availability of financial resources has spurred energy production from renewable sources and strongly boosted the development of technology for optimising (limiting) electricity consumption.
Ecostab automatic voltage optimisers are one of the solutions offered by new technologies to users.
These devices comply with the requirements of IEC 60038 for electric equipment operating tolerances and supply an operating voltage which minimises consumption without impairing performance or reducing reliability. IEC 60038 establishes that the electric equipment must be able to work correctly at an input voltage within ±10% of the nominal value, that is from 253V to 207V for singlephase devices and from 440V to 360V for three-phase devices. This is an essential feature for all electric devices because energy producers establish that the supplied voltage may vary within these limits contractually. As a consequence, if a load is supplied at a value close to the lower operating tolerance limit (-10%) also when the mains voltage assumes the higher value established by contract (+10%), the difference between 253V and 207V in absolute terms is 18%.
This power supply difference allows to:
- obtain a significant saving of energy;
- extend the working life of electric equipment. Ecostab voltage optimisers prevent devices from being powered at higher values than the rated voltage. For example, it is a known fact that the life of sodium bulbs is reduced by 50% when they are powered at a voltage 10% higher than their rated value;
- secure a significant reduction of carbon dioxide emissions. This corresponds to approximately 630 g for every saved kWh of energy.
Ecostab automatic voltage optimisers deliver a stabilised voltage which can be set to the minimum tolerance established in IEC 60038, i.e. -10% (207V). This value is guaranteed also in presence of significant mains voltage variations. Interestingly, these devices are also excellent mains voltage stabilisers.
- Standard single-phase models can deliver a variable voltage from 230V to 207V with input voltage between 207-253V range.
- Standard three-phase models can deliver a variable voltage from 360/207V to 400/230V with input voltage between 360/207V and 440/253V.
Models capable of broader input voltage variations may be built on demand. These may be needed because voltage may sometimes exceed the 10% tolerance specified in the supply contract.
Automatic voltage stabilisation is a key function that sets Ecostab voltage optimisers apart from simple autotransformers, which also reduce voltage but cannot guarantee certain savings due to the continuous voltage variations of the mains.
In order to prevent the delivered voltage from dropping excessively low as a consequence of mains fluctuations, autotransformers can never provide maximum savings. The following diagram shows three different power supply possibilities with average absorbed power and saving for an electric motor.
The area included between the red and the green lines represents the maximum saving achievable by Ecostab compared to the autotransformer economisers.
SAVING AND RETURN ON INVESTMENT
An electronic control circuit detects the voltage delivered by the voltage optimiser and compares it to a reference voltage. If the difference between the output voltage and the reference voltage exceeds the preset tolerance limits, an error signal is generated; this signal may be either negative or positive according to whether the output voltage is lower or higher than the preset value. This signal activates the servomotor which moves the mobile contacts (electrographite rollers / brushes) of the variable autotransformer thus changing the transformation ratio in order to supply the additive or subtractive voltage needed to restore the value within the predetermined limits to the primary winding of the series transformer. The rootmean-square value (RMS) of the output voltage is stabilised and consequently not affected by possible harmonic distortions present in the input mains. This regulation system has the advantage of not having mobile contacts in series to the power supply line.