AVE - Automatic voltage equalizer

AVE – Automatic Voltage Equalizer

The AVE is our most advanced unit and it is based on EM Energy Solutions` revolutionary technology of using electromagnetism to balance and optimize the distribution system at the speed of the current.

AVE is designed for an optimal phase to ground voltage control. With the use of motor controlled variable isolation transformers, accurate control of individual phase voltage is possible. The unit balances voltage imbalances from close to 100 percent (fault condition) to nearly zero percent imbalance.

The AVE has a state of the art power quality meter, which will give the operator detailed status of the network quality and trigger events. Operational status and network information are obtained locally from the HMI panel and from a remote web interface. A cloud solution is also possible so you can access and monitor your system in real-time from anywhere in the world.

AVE`s main components are the three state of the art single phased auto variable transformers, designed in cooperation with Metrel.

The unit uses its powerful computer to constantly log and gather important data from a wide range of sensors to control the auto variable transformers.


AVE optimizes your electrical network efficiency and saves energy, protects assets, and saves costs.


1) Prevent phase voltage imbalance

2) Prevent phase angle differential

3) Eliminate transients and voltage spikes (lightning strikes)

4) Prevent Arc flash

5) Prevent phase voltage instability

6) Reduce voltage harmonics (Phase – Ground)

7) Reduce waveform distortion

8) Eliminate noisy ground reference and frequency instability

9) Prevent arcing ground faults

10) Provide a good and stable ground reference for power system stability to ensure optimal operation of control systems without interruption.

AVE Benefits:

1) Increased operational efficiency

2) Reduced energy consumption

3) Extended lifespan of electrical components and machines

4) Reduced dangers of arc flash and ground faults.

5) Reduced CO2 emissions

6) Reduced maintenance and downtime

7) Saved cost 

8) Increased safety for personnel

9) Advanced Power Quality Analyzer, including webserver, HMI-panel, and energy management software.

10) Alarms for various events like ground faults, transients, voltage imbalance, high harmonic distortions, etc

Documented and proven technology

The Automatic Voltage Equalizer has been through an extensive testing program, including laboratory testing at PNDC (Power Networks Demonstration Centre), and the test report is available on our website under Downloads. We have successful installations in several countries worldwide, including Norway, UK, and South Korea.

The picture above shows the AVE cabinet with the three specially designed single phased auto variable transformers.

Above, you can see the result of one of the tests completed at the Power Network Demonstration Centre. As a baseload during the test, we had three power-resistors each at 10 Ohm connect in delta configuration, consuming around 22,2 kVA. To induce a voltage imbalance, we used a 30 Ohm power-resistor connected between phase A and B, which produced close to 9% imbalance.

From the graph, one can see how the voltage imbalance instantly reduced at activation to 1.32%, together with consumption reduction with 350 VA. We achieved a further reduction in imbalance and consumption by adjusting the ratio on the variable transformers. 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 a larger scale.

The Waveform log above is captured by EMES PQA during welding machine operation at Samsung Heavy Industries and shows the exact moment when AVE is activated. The Waveform before the AVE activation is distorted with a high voltage unbalance (8-9%). After AVE activation, we see a short transitional period of 30-40ms where the unit stabilizes the system, removes harmonic distortion, eliminates transients, and reduces voltage unbalance (0.5%).  After the AVE is activated, we can see a perfect sinus waveform and a 100% balanced system.

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 a control system,  electronics, or any other semiconductor-based equipment. The AVE reacts 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 only 28 Volt!

The picture shows how fast the AVE reacts to a voltage imbalance and stabilizes the system. The system is brought back in balanced and fully stabilized in less than 0.9 ms

Above, you can see a simplified schematic of AVE’s main circuit. The variable transformers are connected in star configuration on the primary side with neutral connected to a ground reference. In contrast, the secondary side of the variable transformers is connected in series with a non-inductive stainless-steel grid resistor. The schematic visualizes the current flow in the AVE during a ground fault. The working principle will also be the same for any other voltage imbalance related problem.

If we look at the phase vector display, we see that the voltages are ideally 120 degrees offset during the fault. The two healthy phases support phase (L3) via the variable transformer circuits secondary side. During the fault, all phase currents will be in phase, making us able to use simple algebra to calculate the ground current. Energy is redirected from the healthy phases to the low voltage phase.

AVE test results and a detailed test report is available on our website. https://emenergysolutions.com/downloads/

Pictures show AVE installed at Samsung Heavy Industries to optimize power quality at one of their robotic welding factories inside the shipyard.

The poor power quality had a direct impact on the welding quality, which resulted in increased arc-flare, blowholes, and other welding-related issues.

A significant welding quality improvement occurred the instant that the AVE was activated. The arc-flare was noticeably shorter, and the operators reported that even the sound of the machine was different. In addition to greatly improved welding quality, Samsung Heavy Industries will, from now on, also benefit from reduced energy consumption, an extended lifetime of machines and components such as welding inverters, and a more reliable cost-efficient and safe electrical system. 

Welding inverters operate at switching frequencies typically 10 kHz, or higher and AVE is the only system that is capable of suppressing and stabilizing the voltage system at these frequencies due to its unique technology!



The AVE is designed for use in a wide range of industries. With AVE installed, all types of three-phase power systems are optimized and protected. Each power transformer requires one AVE. The AVE provides transient voltage spike protection, arcing ground fault protection, phase voltage balancing, and arc flash mitigation. Cost and energy saving by installing AVE typically has a payback time in one year or less.

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