Load Management

Load management is a smart EV charging feature available with Evnex products that safely and efficiently distributes your maximum permitted power across multiple EV chargers connected to a common supply.

In a residential environment, this means you can effectively charge multiple electric vehicles simultaneously without the risk of blowing the supply fuse or damaging your home's wiring. Similarly, in a commercial environment, you can maintain the fastest charging rate possible at any given time as drivers plug in and out of the local charging network while protecting the given power supply from overloading.

There are two versions of this feature that are implemented differently, with differing advantages and installation requirements. Below are key points for you to consider when setting up your Evnex charger to take advantage of the best load management for your situation.

Many commercial sites that Evnex installs at have power limitations and associated loading constraints. Our dynamic solution will take into account the local supply availability, the location’s demand profile and the proposed operational usage. Each site will have its unique set of circumstances, and we will design the solution to maximise charging that suits the EV fleet's needs while minimising costs.

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1. Local Load Management

Local load management (LLM) is the preferred method of implementing this feature if your installation site allows for it. It is more reliable as it does not require a constant connection to Evnex's CP Link Cloud Management portal to function.

This setup is a stand-alone system, independent of Building Management System (BMS), and is designed to protect a given supply from overloading, regardless of what other loads might be connected (provided that the max demand doesn’t exceed supply capacity prior to EV chargers being added).

Local Load Management groups can either be configured with a static upper limit, where supply capacity can be guaranteed; or with a dynamic upper limit by actively monitoring a given supply, in real-time to ensure this supply capacity is not exceeded.

For either scenario, any given charger within the load group can be configured as the primary unit which controls the output and behaviour of all other secondary chargers in the load group.

Where the supply is to be monitored, the primary unit requires the connection of CTs, hardwired via overall screened twisted pair instrumentation cable, appropriately rated to be run into the switchboard (≥230/400V).

A combination of single-phase and three-phase chargers may be included in a given load group. However, single-phase groups may give better results.

A local load management group is set up and can later be adjusted via connection to CP Link, but this connection is only required for the initial setup or when adjustments need to be made.

User-created energy profiles can be set to determine the available power to balance from (e.g. Max 50 amps during the day, 200 amps at night).

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Connection Interruption

If you were to lose internet connection while charging, the local EV charger designated as the group primary would continue to communicate as normal between all the connected EV chargers locally within the group and continue to optimise charging speed as power availability changes. If any charger were to lose the connection between itself and another charger in the group, it would automatically charge more slowly (at 6 amps) as the default slow charging rate.

Evnex chargers also allow you to take advantage of locally generated Solar Charging energy export while incorporating it into the local load management system.

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Load Management / Internet Communication

Scenario 1 - (Ethernet - recommended option)
Suitable for larger load groups, where a cellular network is not available or where chargers are placed too far apart to achieve an integrated Wi-Fi connection.

• Local load management (LLM) control and internet connection will be achieved through ethernet*.
• All chargers must be connected to the same network via individual ethernet cables to a managed switch or router (daisy chaining is not possible for more than 2 chargers).
• The maximum number of chargers connected to a given LLM group via ethernet is 16 (multiple LLM groups can co-exist on the same network e.g. 3x single phase LLM groups)

An Internet connection can also be achieved through cellular or Wi-Fi where available if the ethernet does not have an internet connection.

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For Scenario 1

The maximum number of chargers on each load group is 16 units, including the control unit. 48 charge points can be connected across 3 groups for a 3-phase supply.

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Scenario 2 - (Wireless)
Suitable for smaller groups, within close proximity to each other, and with a cellular network available for all chargers.

• Local load management (LLM) control is achieved via integrated, stand-alone Wi-Fi produced by the primary unit.
• Internet connection will be achieved through a cellular network.
• The maximum number of chargers connected to a given LLM group via integrated Wi-Fi is 11.
• All chargers in the LLM group must be within 30 meters (line of sight) or <10m (not in the line of sight) from each other (subject to site assessment).

The primary unit should be the central charger (physically) to the load group to achieve the best Wi-Fi connection.

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For Scenario 2

The maximum number of chargers on each load group is 11 units, including the control unit.

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Requirements for Local Load Management

• One of the chargers in each load group will be set as the primary unit and requires an overall screened, appropriately rated (≥230/400V), twisted pair instrumentation cable to be run to the supply to be monitored. The number of pairs depends on CTs to be installed (1 pair per CT). For scenario 1, this should be the charger closest to the physical centre point of the group.

• The Evnex-supplied CT(s) must be installed to the phase conductor of the supply to be monitored. (1x CT for single-phase groups and 3x CTs for three-phase groups). CTs currently available are 100A, 250A and 400A.

• The upper end of the supply limit can be set for any given load group e.g. 90A per phase. The load group will dynamically adjust collective output to ensure this limit isn't exceeded, even when other loads come online, provided these other loads are connected to the monitored supply.

• Alternatively, the group can be set up for a static upper supply limit. This would eliminate the need for the CTs, and instrumentation cable, however the supply is not monitored and the assigned capacity for the load group must be available at all times.

• It is vital to contact Evnex, complete the load management commissioning form and follow instructions closely before charging any vehicles.

• Where multiple three-phase chargers are commissioned on a given load group, Evnex recommends that phases are rotated at the charger input, in case a number of single-phase vehicles are connected.

• The minimum allocated output per charger must be 6A per phase.

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2. Cloud-Based Load Management

Load management features that use a continuous connection to Evnex's online control portal CP-Link are referred to as ‘Cloud-based Load Management'.

This type of load management relies on a user set ‘Max Current’ distributed across all the charge points using that circuit. At any time the charge points are not permitted to draw a total current that is more than the ‘Max Current’ set for that Load Balancing group.

Within CP-Link, a load-balancing group is created by placing the charge points into a Load Balancing group with a configured Maximum Current. An algorithm runs to calculate how much of the group's current can be allowed to each charge point.

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Use Cases (For Cloud-Based Load Balancing)

Cloud-based Load Management is best used for large sites where EV charge points are distributed across a wide area. For example: You operate a charging fleet across a campus with 3 car parks separated by a distance that a link by Wi-Fi is not stable enough, and it would be impractical to run an ethernet cable between all chargers on the campus.

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Requirements and limitations for Cloud Load Management

• Each charger must be connected to the internet via a reliable Wi-Fi or Ethernet connection. A cellular connection is not preferable and should only be used where reception is very strong and reliable.
• The chargers will be commissioned as a load group.
• The collective upper limit for a given load group can be set, e.g. 80A per phase between all chargers in the group.
• The upper supply limit capacity must be available at all times as the supply is not monitored.
• The load group will dynamically adjust output to ensure this limit isn't exceeded.
• For three-phase chargers, the load balancing group will not distinguish between single or three-phase vehicles plugged in and will assume that loads are equal on all three phases and adjust output accordingly.
• Where multiple three-phase chargers are commissioned on a given load group, Evnex recommends that phases are rotated at the charger input terminals, in case a number of single-phase vehicles are connected.
• The minimum allocated output per charger should be 10A per phase.
• Best results for supply distribution are achieved using single-phase chargers only and setting up a load group per phase.
• The maximum number of chargers connected to a given load group is 10.
• Multiple load groups can be set up on a given supply.

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