AVEAutomatic Voltage Equalizer
Automatic Voltage Equalizer
The AVE series of units are a new type of power quality optimizers based on a revolutionary new patented technology which utilize electromagnetism to stabilize distribution system.
AVE is an EHRGS (Electromagnetic High Resistance Grounding System) that reacts on any voltage imbalance and equalizes the voltage between all phases with the speed of the current.
The AVE serves as a Surge Suppressor, Voltage Regulator and Harmonic Filter, without the need for MOVs. AVE makes an instantaneous correction to any phase voltage that is out of balance and prevents transient voltages.
Additionally, it uses electromagnetism to control voltages, protecting the control systems, electronics and reducing degradation over time or through repeated usage.
AVE – Automatic Voltage Equalizer protects all equipment downstream from transformer secondary, making other power quality devices unneccessary and obsolete, such as SPDS, Voltage Regulator, HRG etc.
The technology have gone through thorough testing both in-house, laboratory and in the field.
We recently completed detailed testing and presentation at PNDC (Power Network Demonstration Center) in Cumbernauld Scotland where a full test report can be obtained on our website. Units have also been installed and proved their unique capabilities in several countries including Norway, South Korea, UK and more. Just recently we proved the technology at one of the worlds largest shipbuilding manufacturers in the world Samsung Heavy Industries with astonishing results..
Poor power quality is a huge, expensive and increasing problem in industry.
Voltage imbalance causes Electric motors to operate at higher temperatures and lower efficiency, which results in significantly reduced life expectancy and increased power consumption. For electrical equipment, a rule of thumb is that an average temperature increase of 10 degrees Celsius equals a 50% reduction in life expectancy.
Equipment failure and system lockup result in unreliable operation with downtime and production stop.
Voltage imbalance and voltage dips often lead to blackouts which again can lead to production stop.
Just 3% voltage imbalance can cause as much as 18-30% current increase, which again will cause considerably more wear on motors and increased power consumption.
The cost of power failure is potentially very high. Many industries run delicate processes that require a fully functional production line. Production stop related to faulty equipment can significantly impact production output and, subsequently, a company’s earnings.
Figure above explaning how voltage imbalance effects a three phased electro motor.
Cost Saving example:
3 phase AC motor with as little as 3 % voltage imbalance creates 3.4 % reduced efficiency in AC motors. If we consider a plant operating 20 AC motors at 100 Hp for 8000 hours per year, this will correspond to more than 400 000 kWh wasted energy. Additional costs based on an estimated kWh price of 0.17 € will be at more than 6 8 000 €
Another high potential industry hazard is Arc-Flash. Arc-Flash is one of the most dangerous incidents for both personnel and equipment. It is an electrical explosion/discharge that results from a low-impedance connection through the air to ground or another high voltage phase in the electrical system. It may also be initiated through accidental contact, underrated equipment compared to available short circuit current, contaminated insulated surfaces, as well as other causes.
An arc-Flash event can dissipate large amounts of deadly energy in form of shock wave and superheated metal plasma. Temperatures can reach as high as 19 000 degrees Celsius, even hotter than the surface of the sun.
This kind of energy can set fire to clothing and severely burn human skin in fractions of a second. According to Industrial Safety and Hygiene News report, there is, on average 30 000 Arc-Flash incidents every year with an estimated 7000 burn injuries, 2000 hospitalizations, and 400 fatalities in US alone.
Reduction in life expectancy and increased maintenace costs
A general rule of thumb is that an AC motor will reduce its life expectancy
by half for every 10 degrees 𝐂 increase in temperature. The temperature will increase two times the voltage imbalance squared.
Our example with 3 % imbalance will correspond to 18 % temperature increase. The current will also increase 18%, but sometimes as much as 30% percent ! Assume NEMA class B motor with normal operational temperature at 95 degrees 𝐂. With 3 % voltage imbalance the temperature will increase to 112 degrees 𝐂. This will reduce the lifetime from 200 000 h down to 68 500 h. A total reduction of almost 66% This is just one example of how just a minor voltage imbalance can greatly increase costs in industry.
Reduction in fuel consumption and 𝑪𝑶𝟐 emissions based on voltage imbalance Following is a cost example taken from a marine vessel.
Today’s maritime diesel cost is approximately 540 €/Mt. Total efficiency factor from diesel engine to generator output is close to 32 %. Taking into consideration an additional 15 % loss (transformer, VFD, and electric motor), we are left with a total efficiency factor of 27.2 %. In short we utilize less than one third of the fuel’s energy content.
Based on these numbers and that 1 kg of diesel contains 42 400 kJ, we consume 0.314 kg of diesel for each produced kWh. The price for each kWh will be 0.17 €/ We can consider a marine vessel running a large amount of electric motors with 3 percent voltage imbalance (same as previous example), consuming on average 8 MW. By balancing the voltage, the efficiency will increase with 3.4 %.
The total fuel cost reduction in one year will add up to 404 000 € If we look at the same example in terms of 𝐶𝑂2 reduction, 1 Kwh corresponds to 0.98 kg 𝐶𝑂2. Total reduction in 𝐶𝑂2emissions over the course of one year will be more than 2300 metric tons
With AVE installed on your electrical systems your business will benefit from the Safest, most reliable, and most economical electrical system achievable.
AVE saves energy and money by ensuring a stable distribution system with phase to ground voltages balanced. Most electric systems have some imbalance and a payback can be calculated as follows:
*Approximately 1.4% kW reduction per 1% of voltage imbalance corrected, if Energy cost is €100,000 per month and voltage imbalance is 1%, the savings would be €1,400 per month only from Energy reduction. (See PNDC test report for detailed information on AVE`s unique capability to balance power systems.)
*The capacitive charge current, which is normally drained to ground continuously, is used, by AVE to correct the phase to ground voltages.
The screenshots above shows real-time information from the unit’s power quality analyzer during welding machine operation at Samsung Heavy Industries. The screenshot is to the left is taken during welding machine operation with the AVE deactivated and the screenshot to the right is with AVE active. Voltage unbalance went from 8.04% to 0.59 % after AVE activation. The power factor increased from 0.927 to 0.964 and a significant drop in energy consumption was seen after AVE activation. Active power consumption went from 384,586 kW to 340,960 kW, a reduction of 43.626 kW (11.32 %). Reactive energy consumption went from 97.4402 kVAr to 47.0076 kVAr a reduction of 50 %. Apparent power went from 415.086 kVA to 353.817 kVA, a reduction of 14.76 %.
Graph from laboratory testing at PNDC showing AVE`s uniqe capability to balance distribution system. AVE reduced the total voltage imbalance from 12.09% to 0.23%!
As the AVE single phase transformer windings are tuned by units controll system, the level of voltage imbalance reduces until a optimal and balanced system is achived.
Figure above show the voltage phase angles logged during voltage imbalance testing. Phase angles shown are for the AVE off and the AVE on with transformer ratios tuned to approximately 75%. In both cases the phase angles are shown to move closer to their ideal values, i.e. those separated equally by 120 degrees, when the AVE is switch on and is active.
The more ideal phase angle separation of 120 degrees ensures that three phase power transfer at any moment in time is constant, which is preferable to many three phase loads, including motors, and can have impacts of the longevity of the motor and its efficiency.
*Protect all downstream equipment and prevent Arc Flash events by balancing the phase to ground voltages continuously, not allowing ground faults to develop. The AVE`s control system will give alarm telling the operator that a grounded phase is developing. The system continues to operate without any need for shutdown before planned maintenance. Arc Flash is perhaps the worst hazard with regards to electrical system and causes thousands of personal injuries, fatal and nonfatal every year. With AVE installed the risk of an Arc Flash is reduced by 80-90%.
*AVE limits the ground fault current to less than 1 amp regardless of the type of grounding systems (See PNDC test report for detailed information on how our unit balance the system in case of a ground fault.)
The data in Table above highlights the very low levels of current and power flowing through the AVE device when it is active and balancing the voltages.
AVE consumes less than 0.03 Amps flowing in all phases and 0.1 Amps flowing to ground. This low current flow highlights the low energy consumption associated with the uniqe way the AVE balances voltages.
Above you can see the result of one of the tests completed at the Power Network Demonstratio Cnenter. As a baseload during the test we had 3 power-resistors each at 10 Ohm connect in delta, consuming around 22,2 kVA. To induce a voltage imbalance, one 30 Ohm power-resistor was connected between phase A and B, which induced close to 9% imbalance.
From the graph one can see how the voltage imbalance is instantly reduced to 1.32% and consumption is reduced with 350 VA when the unit is turned on. By adjusting the ratio on the variable transformers, both the imbalance and energy consumption is further reduced. The energy reduction was close to 500VA.
If we calculate this into kW hours over a year, it would add up close to 4400 kWh. Depending on local electricity costs, one could just imagine the savings possible on larger scale system!!
AVE Ensure a reliable electrical system with prolonged lifetime of electrical equipment and components. Stop the unplanned shutdowns, operation malfunctions and Increase production output.
- *By stabilizing phase to ground voltage, motors, transformers and other inductive loads will run cooler and use less energy.
- *Reduce the effects of single phased sags and swells, ensuring maximum up time for factories and reducing stress on motors and electrical components. In the case of a single-phase event, the lost phase will be corrected by transferring energy from the two other phases, this will minimize damage and reduce the imbalance. In most cases the 3 phase loads will continue to operate, until the condition is addressed.
- *Eliminate noisy ground reference and frequency variations.
- *Correcting phase angle differential displacement continuously at the speed of current flow, helps to solve the control system lockup problems, many of which happen while recovering from outage conditions.
- *Phase to Ground Voltages are corrected continuously, whether caused by current imbalance or temporary Arcing Ground Faults.
- *Provide a good and stable ground reference for power system stability to ensure optimal operation of control systems without interruption.
- *Transients and surges are eliminated, whether caused by lightning or normal internal events. AVE can withstand the most powerful surges without damage to itself or anything it protects.
- *Remove voltages harmonics, phase to ground. Processor equipment and control systems that tie their data reference to ground will be impacted by these lines to ground harmonics.
- *Eliminate harmonics on grounded phase. When a ground fault appears on a voltage system, there is an appreciable increase in voltage harmonics. These harmonics tend to circulate among the connected loads where they generate additional heat and could interfere with control systems and other electronics.
Figure above shows the difference between existing surge protection technology and AVE based on electromagnetism. Existing semiconductor-based surge protection devices are too slow and often allow as much as five times nominal voltage into the system. These transients will drastically shorten the lifetime of any electronics or semiconductor-based equipment. The AVE react with the speed of the current and does not allow any significant increase in the voltage. During laboratory testing the AVE mitigated a charge of 10 000 Volts to a spike of 28 Volt!
Figure above shows system with ground fault on phase A with AVE Off and AVE On.
The figure also illustrates how AVE eliminates the dangerous overvoltage’s
experienced by healthy phases during fault conditions, and lower the phase voltages to nominal, lowering the risk of damage to
equipment and injury to people to a minimum.
AVE reacts and stabilize a faulty system in less than 0.8ms, this due to AVE`s revolutionary technology based on electromagnetism.
Figure show the respective voltage phasors of all three phases when the two ground faults are applied.
Without AVE voltage phase angles are not equally spaced by 120 degrees . When the AVE is activated, voltage phase angles return to nominal positions, equally spaced by 120 degrees.
Graph shows waveform graph and phasor diagram for a 3 phase distribution system with ground fault on phase B when AVE is activated.
As awareness grows of the extreme danger of arc flash hazards for electrical and maintenance workers the focus on arc flash prevention grows.
As shown in Figure above, damage from an arc flash increases rapidly with time, so the faster the system can react to the fault, the less damage there will be. AVE react with the speed of the current flow and by balancing the phase to ground voltages continuously, not allowing ground faults to develop it reduces the risk for an arc flash by 80-90%!!
Comparison of grounding systems and characteristics
Figure below shows the importance of having AVE installed on your electro system. Automatic Voltage Equalizer reducing the safety hazzards related to arc flash, over voltage, ground faults and at the same time making the power system more reliable and energy efficent!
How does this new technology work?
The laws of physics do not change, but our understanding of them does, Automatic Voltage Equalizers technology is based on the fundamentals of electromagnetism and that the unit will react on any voltage imbalance with the speed of the electromagnetic field. The AVE’s purpose is to stabilize phase voltages with reference to ground, thus preventing well known problems related to unstable voltage supply on distribution systems. Unbalanced voltage can be induced by unbalanced loads, transient events such as sags and swells caused by start and stop of inductive loads, lightning strike and more.
The AVE’s main components are 3 single-phase variable isolation transformers connected as a 3-phase transformer with a wye connected primary and a delta in series with a resistor connected secondary. The ballast resistor in the secondary side is chosen to limit the current to maximum current for the transformer design and prevent ferro resonance between primary side stray capacitance and transformers magnetizing reactance. If the phase voltages are balanced, there will be no voltage drop across the secondary side circuit, thus no current will be induced in the secondary side. This will also be the case for primary side current draw since no load is seen on the transformer circuit secondary side.
If we look at an unbalanced scenario, the secondary side voltage will no longer be equal to zero, and a voltage drop will occur across the secondary side resistor. The magnitude of current in the secondary side will be determined by the impedance of the low voltage phase and the size of the ballast resistor. The phase with the lower voltage will be seen as a load from the transformer circuits secondary side, and energy will be drawn from secondary to primary side. Looking at the schematic below, we can see how capacitance is raised in the low voltage phase by current being fed back into the low voltage phase.
Assuming a maximum primary imbalance on a 230V three phased system of: 0 v, 230 v, 230 v, secondary voltages will depend on the transformers ratio, let`s assume a ratio of 1 : 2 on all three transformers, secondary voltages about 0 v, 115 v , 115 v would be expected. Secondary side voltages will therefore be 200 v (115 v x √3).
Current induced in the secondary side is based on the combined voltage from the high voltage phases together with the total impedance which will be the sum of the low voltage phase impedance and ballast resistor. If one applies the well-known rule of Kirchhoff’s fundamental voltage law, which states that the algebraic sum of all voltages around any closed loop in a circuit is equal to zero, the voltage drop across the total impedance in the circuit can be determined by the vectoral sum of the high voltage phases in the circuit. Using this value, we can calculate the secondary side current.
The amount of contribution from the unit is based on the magnitude of the voltage imbalance and the variable ratio of the transformers. The variable transformers will correct steady state voltage imbalances, by reducing ratio on the low voltage phase and increasing ratio on the healthy phases. By doing this, more energy will be transferred from high to low voltage phases.
For transient surges such as voltage spikes caused by lightning strikes this will be detected as a very large voltage imbalance which again will cause the unit to react more. The higher the voltage imbalance the more the AVE will counteract it. The problem with surge protection devices is that they are to slow to prevent damaging voltage levels into the system. Because of the speed of the AVE it can suppress the transients before they reach damaging levels, thus protecting all downstream equipment.
AVE is easy to install and connects in parallel with the distribution systems like any other 3-Phased load to the power system, no other changes are required!
AVE is designed to be connected in parallel on the transformers secondary side and as close to the transformer as possible. This will ensure optimal protection of all downstream equipment connected to the same distribution line.
Additionally, the units are equipped(optional on AVE Mini) with one of the market most advanced network analyzers that gathers all important information on network status and presents this on the local HMI panel, webserver, and through local area network. Alarms are given for various events like ground faults, transients, voltage imbalance, high harmonic distortions etc..
This network topology shows how AVE (optional on AVE Mini) is integrated into the SCADA system.
The power quality analyzer (PQA) measures power quality variables and transfers this information directly through either wireless or wired network to the AVE . Information from the PQA is also obtainable through WEB interface or at local operator stations. For more information read more under PQA.
Animation video explaining AVE’s functionality against ground fault
Animation video explaining AVE’s functionalty against transient events.