Dynamic Phase Balancing


A long-standing industry problem is where three phase AC supply to sites can encounter an unacceptably disparate load on a single phase. There can be various reasons for this, perhaps a newly installed air-conditioner starts, perhaps the site equipment has been upgraded beyond the original load specifications with a phase demand imbalance, perhaps a miss-matching number of rectifiers have been installed. The consequences of this increase of load on a single phase is that the site AC breaker may trip or the full AC power supply cannot be used.

What then? Upgrade the entire AC supply, trenching in new cabling with improved breakers? An expensive option with who knows what site specific pitfalls, especially when an equipment upgrade is mandatory across an entire national distribution network.

What is required is a solution that the existing power supply infrastructure can provide.

Which is what Enatel’s Dynamic Phase Balancing does. As the power drawn exceeds supply availability and threatens to trip a breaker, Dynamic Phase Balancing drops back the system load on the phase in question. As the rectifiers on that phase are turned down, the rectifiers on the other phases are turned up to maintain stable supply to the DC bus. Even, if necessary, supply from the site batteries can be engaged to assist if the rectifier turn down becomes too severe. It can be an ongoing juggling act, limiting the draw on batteries, preventing overly rapid impulses and inrush currents as the AC demand fluctuates and supply sources engage. Which in turn requires that the phase balancing be responsive in real time, reacting in rapidly to the electrical supply requirements. This is the dynamic component of Enatel’s phase balancing solution. Where accurate monitoring and timely reaction prevents stressing the system, fine tuned to match the specific assets deployed at site.

Here is the core of Enatel’s patents around our solution, where phase demand is managed using modern technologies in an electronically smart manner. Enatel’s intellectual property ensures that the phase in question is limited to exactly to the breaker rating curve.

Moreover, and crucially, Enatel’s Dynamic Phase Balancing is incorporated into our EM4x energy manager controller. It is not some large piece of separate equipment, the complex deployment seen in data centres attempting to eke out final distribution efficiencies, but rather is offered ongoing as a licensed feature available anywhere an Enatel DC system incorporates an EM4x.

There are other key applications for Enatel’s Dynamic Phase Balancing.

Another well known problem is the long-term effect of unequal phase demand on gensets. In an extreme case sudden draw on one phase can damage the generator immediately. More typically though the constant spinning of the turbine being disproportionately pulled in one direction severely reduces the genset life span. Often in a manner undetected till complete early genset failure. Incorporating Dynamic Phase Balancing for three phase hybrid sites is always to be recommended.

It should also be noted that the current limiting aspect of Enatel’s Dynamic Phase Balancing has use cases in single phase applications. Where any system circuit breaker needs to be protected, Dynamic Phase Balancing can be introduced.

For Enatel’s customers particular importance should be given to phase balancing with the upgrade of existing telco sites to 5G. With the significant increase of 5G equipment power demand when compared to 4G phase balancing can mean the difference between being able to successfully upgrade using existing infrastructure or not. Phase balancing should be included as a standard requirement across all site systems.

Enatel’s phase balancing feature utilises the system controller’s ability to individually control the output of each set of rectifiers connected to each AC phase input to smooth out phase imbalances on the grid supply. An example of a system actively balancing phases is shown here

To read more, download the white paper here.