Imagine your home electrical system is like a three-lane highway. Each lane represents a phase through which electricity flows. Normally, traffic is distributed evenly across all three lanes.
However, if you connect an electric vehicle with a single-phase charger to a wallbox, it is as if all the cars suddenly want to drive in only one lane. This lane becomes overloaded, while the other two lanes remain empty. This is known as phase imbalance.
In Germany, this "highway" may be loaded with a maximum of 20 amperes. This corresponds to approximately 4.6 kW of power. If your car draws more power than this, the "lane" becomes overloaded.
Why is phase imbalance a problem?
- Overloading: The overloaded lane (phase) can overheat and, in the worst case, lead to damage to the electrical installation. Imagine the heavy traffic in one lane causing cracks in the asphalt!
- Imbalance: The power grid is designed for an even load across all three phases. A significant phase imbalance can lead to instability and disruptions in the grid. This would be like the highway becoming unbalanced due to the uneven weight of the cars.
What does the wallbox have to do with this?
The wallbox is the "gas station" for your electric vehicle. It regulates the flow of electricity and ensures that the phase imbalance does not become too great.
- Intelligent wallboxes: Modern wallboxes can measure phase imbalance and adjust the charging current accordingly. This prevents any single phase from being overloaded. They function like an intelligent traffic control center that distributes cars evenly across the lanes.
- Adjustable wallboxes: With many wallboxes, you can set the maximum charging power to limit phase imbalance. This is like setting a speed limit on the highway so that too many cars do not enter one lane at the same time.
In summary: Phase imbalance occurs when electricity is distributed unevenly across the three phases of the power grid. Wallboxes help to limit phase imbalance, thereby preventing damage to the electrical installation.