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 video explains how the Zaptec charging solution in theory. 

Zaptec's unique phase balancing solutions ensures 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 buildings 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 installations runtime, e.g. vehicles are connected, current limits change, and so on, will trigger the load balancer to run. 

There are many factors that 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 function allows you to adjust the maximum and minimum power the charging station should provide. The maximum value indicates how much power the charging station should output, while the minimum value indicates the minimum power required for the charger to start charging.

    Only users with service access or owners of the entire Zaptec Pro installation/system can change this setting. The owner and user of the charging station cannot change this themselves. This is because system charging is often configured with values that affect the entire installation.

  • Maks og min ladestrøm
    Denne funksjonen lar deg justere maks og min strøm ladestasjonen skal gi ut. Maks verdi tilsier hvor mye strøm ladestasjonen skal gi ut, ,mens min verdi tilsier det minste laderen trenger for å starte lading. 
    Det er kun brukere med servicetilgang eller eier av hele Zaptec Pro installasjonen/anlegget som kan endre på denne innstillingen. Eier og bruker av ladestasjonen kan ikke endre dette selv. Dette er fordi systemlading ofte er satt opp med verdier som påvirker hele anlegget. 


  • Max phases
    The maximum number of phases a charger can be allocated (one or three). Can be used together with the charger 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.

  • Prioritized 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 optimizes offline current and phase for installations every hour, ensuring 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. The offline current and phase setting is sent to the charger when it's online. If a charger goes offline, it will provide current according to the offline settings, and the balancing algorithm will reserve offline currents to prevent circuit breakers from triggering.


Current status

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

  • Charge queue
    Depending on the installation max and available current, and the number of active chargers, there may not be enough power in an installation to start new charge sessions. Sessions will be queued if there is not enough power and will be started as soon as other sessions finish. Queued sessions are started in the order they were connected. If sessions need to be stopped when installation max or available current is decreased, this is also handled by the charge queue. Sessions are started and stopped in a FILO order (First In, Last Out), meaning that the first started session is the last stopped.

  • 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 utilized 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 chargers 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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