Zaptec Pro dynamic phase and load balancing

Zaptec Pro load and phase balancing enables the maximum possible charging capacity for each installation. It provides dynamic phase allocation, rotation, and balancing as well as load limiting.
This feature is available on all chargers that are registered and connected with the Zaptec Portal.


This 3-minute video offers a glimpse into our patented technology, our aspirations, and approach.

Zaptec's unique phase balancing solutions ensure optimal use of all three powered phases. A lot of electric vehicles charge on only one of the phases, but with our system, the load is automatically distributed to all three phases. When several cars are connected the charging effect changes to provide everyone with power.
If you have limited capacity in your building you can measure your building's power consumption using the Zaptec Sense. The charging system then automatically adapts to the building's power consumption. 


Do you want to see how the load and phase balancing can work between the chargers?
Try out our inCharge demo. Click on the chargers and watch the system distribute the load to the different phases. 

Factors that affect the charging solution  

Changes in an installation's runtime, e.g. vehicles are connected, current limits change, and so on, will trigger the load balancer to run. 

Many factors are taken into consideration when resolving the optimal charge configuration for an installation. Such as cloud settings in the Portal, current status, and power management.

Installation settings

  • Network type
    We support three-phase charging on both 400V TN and 230V IT (Norway) installations. For three-phase IT installations, the chargers are set to single-phase charging by default. The installation will balance on all three phases, even if the vehicles only receive single-phase charging. This is bc very few vehicles support 3phase charging on IT. 

  • Charging system circuit breaker (A)
    The maximum total current that can be supplied to the installation. This is normally set to match the rating of the incoming circuit breaker. It is safe to set this value to less than the rating of the incoming circuit. Never set this value to exceed the rating of the incoming circuit. The setting is only available for users with Service permission.

  • Circuit breaker (A)
    An installation consists of a single charging system circuit breaker and one or more circuits. Circuits are configured via the Zaptec Portal. This setting should usually match the physical circuit's circuit breaker, and will limit the current allocated to chargers in the circuit. Because this setting needs to match the physical constraints of the installation, it is only available for users with Service permission.

  • 3 to 1-phase switch current
    This setting determines when a vehicle should be switched from three-phase to single-phase charging. By default, this is done when the charge current drops below 15A. For most installations, this configuration will provide the best capability. For installations that have a limited number of charging stations, or a low maximum installation current (<32A), it may be useful to set this current lower to allow more chargers to operate on three phases. If a TN 3-phase installation should only offer single-phase charging, the setting can be set to 32A. The setting can be changed by users with Owner or Service permission.
    • Allow chargers to return to three-phase charging
      In addition to the 3 to 1-phase switch current, you have the option to allow the charging station to switch between one and three-phase charging. The slider can be used to set the number of switches allowed before locking to a single phase. Can be changed by users with Service permission. 


Charger settings 

  • Maximum and minimum current
    This feature lets you control the maximum and minimum power output of the charging station. The maximum value sets how much power the station should provide, while the minimum value sets the least power needed to start charging.

    Only users with service access or owners of the entire Zaptec Pro installation can adjust this setting. Charging station owners and users can't change this themselves. This is because system charging settings often affect the entire facility.

  • Max phases
    The maximum number of phases a charger can be allocated (one or three). Can be used together with the charger's maximum current to limit how much power the charging station should provide. This setting is available to users with Owner or Service permission on the charger.

  • Prioritised current
    By setting priority to a charger it will be allocated charge current before other charging stations. This will affect the fairness of the system and can prevent other charging stations from providing efficient charging. If capacity is low, or other charging stations are configured with priority, we cannot guarantee charge current. You can set priority under the chargers Settings in Portal. 

  • Charger online status, offline current, and phase

    The Zaptec Portal automatically optimises the offline current and phase selection for all chargers within an installation every hour (when online). This ensures that offline chargers can provide as much current as possible without triggering any circuit breakers in case all chargers in the installation are active at the same time.

    Even if a charger goes offline, it remains functional, operating according to the preset offline settings. Depending on these settings, authentication may still be required for payment and access functionality, even during offline periods.

    Please note that offline operation is not the charger's normal state, and while it may function properly, intentionally keeping the charger offline for extended periods is not recommended.

Current status

In addition to these settings, the current status of the installation is also part of the equation. 

  • Charge queue
    If there isn't enough power available to start a new charging session, the system queues sessions and starts them as soon as other sessions finish. Queued sessions follow the order they were connected; The first charger that started will be the last to stop. So, if your charging session started earlier, you'll get to charge before someone who started later. If the system has to stop charging sessions because there's not enough power, it stops the most recent ones first to be fair to everyone.
    • For example, if the available power is reduced to less than 6A (1-phase, 1.4 kW, available per connected car by default) the system will start stopping charging sessions. The charger that started the earliest will be the last one to stop, ensuring that all cars get a fair share of charging time.
    • Trouble understanding? Picture a busy restaurant. Each customer is a car needing a charge. If there aren't enough chefs, orders go in a queue. Just like in the restaurant, the system serves cars based on arrival. If there's not enough cooking capacity (or power), it serves those who arrived first, ensuring fairness for everyone.

  • 3-phase charging not supported by vehicle
    If a vehicle is allocated three phases but does not use more than one phase, it will be relocated to a single phase. This prevents Phase 1 from being excessively utilised in these scenarios. If a charger has not used more than one phase for the past 5 minutes, it can at any time be moved to a single phase. The charger is only moved when required.

  • Preferred charge phase
    When allocating a single phase to a charger, the charger will prefer its offline phase.

  • Sticky phase
    A charger that is allocated a single phase, will keep this phase for as long as possible. If a charger needs to be moved to balance the installation, the last connected charger is moved first.
    Chargers that have been offline in a charging session, will be locked to its offline phase for the duration of the session. This will prevent chargers from switching phases when going offline/online. If the charger is locked to a phase with no available power (due to manual or automatic available current setting), it will not provide current until there is available current on the charger offline phase.

  • Sticky single phase
    If a vehicle in an installation supporting 3-phase charging has for some reason been allocated a single phase, e.g. due to 3 to 1 phase switch current, it will stick to single-phase charging for the duration of the session. The reason for this is to limit the number of stop/start commands sent to a charger. We try to limit this as some vehicles abort charge sessions after multiple stop/start cycles.


Power management

The applied power management scheme will also be a factor in this. For Zaptec Pro installations, there are three different power management options.

  • Manual power control
    This is the basic power management tool, where the system adheres to the setting: Charging system circuit breaker (A). Additionally, it is possible to reduce available current on one or more phases. This can be helpful if there are known loads on the same circuit that are not from charging stations.

  • Scheduled power control
    The scheduled power control allows the installation owner or service provider to create a time schedule of the available power of the installation. For more information, see this article.

  • Automatic power management (APM)
    By installing an APM ( available models might differ between countries), it is possible to balance the load on the installation towards the buildings main fuse or similar. 



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