Voltage Optimisation & Power Factor Correction
Voltage Optimisation is an electrical energy saving device which is installed in series with the mains electricity supply. The principle of Voltage Optimisation relies on the fact that electricity consumers are supplied with significantly higher voltages than necessary in order to compensate for losses elsewhere within the Grid.
On this basis around 90% of electricity consumers pay for and use more power than they need to due to the intrinsic over supply of voltage by the Grid.
The basic principle of all Voltage Optimisation equipment is to reduce the voltage level from that of the incoming supply, to a new optimised level allowing for energy reduction.
This voltage reduction can be anywhere between 5% – 15%.
Digren Energy represent manufacturers whose units optimise a site’s power supply to enable financial, energy and CO2 savings, simultaneously improving Power Factor, capacity (MD) and reducing maintenance.
What are the benefits of installing voltage optimisation?
Reduces energy consumption and costs by up to 15%
Reduces carbon emissions by up to 15%
Protects all equipment from high voltage surges and transients
Extends life of electrical components, reduces maintenance
Improves Power Factor
Reduces carbon taxation
Immediate ROI and increased bottom line
How do I know if Voltage Optimisation is suitable for me?
We will carry out a site survey for you. This will involve us placing a number of meters throughout the line to measure the flow of electricity within your site. These meters remain on site for between seven to ten days. We then download the data and present our proposal to you.
Our proposal will clearly outline the amount of savings that can be expected and a full breakdown of how they are achieved. The proposal will also detail the capital cost of the equipment and the return on investment (ROI).
We generally, only recommend this as a solution if the ROI is sub three years.
More benefits about Voltage Optimisation
Power factor correction equipment can not only substantially reduce your electricity bills, it can also save in other ways. As well as saving you money on demand, it is also a very cost-effective way of increasing the capacity of your main cabling by up to 50%.
For example a 0.7 power factor (which is quite common), when properly corrected, will increase your main cable capacity by 30% and could decrease your relevant, electrical maintenance factors by a similar figure.
Compare your latest electricity bill against the same billing period for last year, any inexplicable increases of 10% – 20% or more per annum on your demand component may be due to low power factor. This may need power factor correction, or if power factor correction equipment already exists, it may need servicing, or it may need to be added to in size because your business has expanded and it may be severely over-extending its original-designed capacity.
Improving power factor on a network will reduce the total power consumed by an electrical installation and will also provide the following benefits:
Financial Saving
By reducing power consumed electricity costs are reduced.
Extended equipment life
Reduced electrical burden on cables and electrical components.
Increase load capacity
Provide additional capacity for other loads to be connected.
Environmental benefit
Lower carbon emissions and fossil fuel depletion by power stations.
What is power factor correction (PFC)?
Inductive loads such as motors, compressors, lifts, refrigeration equipment and other inductive loads use both active (kW) and reactive (kVAR), also known as ‘Wattless’ power. You are charged for the units used in kilowatt hours (kWHrs), so if you use a piece of equipment rated at 1kW for 1 hour you clock up 1 kWHr. This is fine for the energy suppliers if the equipment uses only active power such as a heating element. However, the providers have to allow for both kW and kVAR. This overall supply is measured in kVA. Most providers allow you to use a certain percentage of reactive units without charge. If these units exceed 30% of the kWHrs you will see a ‘low power factor surcharge’ line on you bill.
To counteract the kVAR a well trusted method is to introduce capacitance into the system, this is achieved with a power factor correction panel. As loads in premises are intermittent the panel measures the system and only adds capacitance when required. This will eliminate the surcharge.
Typical Power Factor Corrective Unit
Transformers and induction motors
Transformers and induction motors are a prime cause of low power factor for many businesses. Poor power factor is an issue especially for businesses with large numbers of small fractional horsepower motors, those who purchase cheap or poorly made motors, and those having oversized, under-loaded motors.
Most small fractional horsepower motors have low power factors in the 50 to 60 percent range. As the rated horsepower of the motor increases, in general, the power factor of the motor at full load increases. Therefore, larger horsepower motors have better power factors than small horsepower motors if each motor is properly loaded.
Power factor correction capacitors
A poor power factor can be improved by adding power factor correction capacitors to the plant’s distribution system. Correction capacitors provide needed reactive power (kVAr) to the load. Therefore, the Electricity Supply Company is freed from having to supply it. Power factor correction capacitors reduce the total current supplied by the Electricity Supply Company to the load and as a result the distribution system capacity is increased.
Capacitor ratings
Power factor correction capacitors are rated in electrical units called “VAr”. One VAr is equivalent to one volt-ampere of reactive power. VAr is the unit of measurement for indicating just how much reactive power the capacitor will supply.
Blocking reactors
In most cases it is necessary to reduce the effects of the harmonic currents. One way of reducing harmonic currents is to install an inductance (blocking reactor) in series with the capacitor. The blocking reactors protect the electrical installations and equipment but it does not eliminate the harmonics. The reactor value should be calculated and designed in order to reduce the resonant frequency of the circuit to a value lower than that of the lowest harmonic in the system. A capacitor equipped with a filter reactor is protected from harmonics regardless of the layout of the network to which it is connected. Except in some cases when switching in steps the inductance and capacitance values could add up to equal one of the harmonic frequencies in the system causing resonance.
