What are the main benefits and advantages of DLM? 


  1. Multi-vendor capability at the same site. Any mix of Virta-tested OCPP 1.6JSON chargers can be used in the same DLM group with consistent performance => You are able to choose your preferred cost-effective charger vendor, no charger vendor lock and lesser risks when all the eggs are not in the same basket (e.g. downtime, firmware updates and so on)

  1. Easy remote configuration of DLM groups and limits through the Virta system => saves operational expenses and enables energy control for larger groups of chargers also in different locations 

  1. Compatible with Virta demand response and congestion management services for providing grid services => enable major further business opportunities 

  1. Cloud-based logic enables instant future feature updates without requirements for charger firmware upgrades => lower implementation and operational costs as fewer manhours are needed for manual work during solution lifecycle

  1. Future roadmap functions, example: capability for charging prioritization based on EV charging customer profile => further business opportunities 


What is DLM 1.0? 

DLM 1.0 is a solution for sites where the electrical installation is dedicated to EV charging stations. The group of chargers is set with a maximum limit of electrical current which is evenly distributed between chargers that have a car charging. DLM 1.0 takes into account each chargers' operational minimum and maximum limits (e.g. the charger is always supplied with the least amount of current to remain operational regardless of the DLM limit)


How is current (I) distributed between chargers in a DLM group? 

The charger site's electrical current is evenly distributed between chargers that have a car charging. If a single charger is provided with an electric current that enables more power than the charger can consume, the "leftover" current will simply not be used 





What kind of limitations are there that affect the chargers within the DLM group? 

With DLM it is possible to set whatever values using the UI, but there are at least the following realistic limitations: 


  1. The electric installation of the main connection / power supply. Ultimately, these installations define what is the maximum level of current available (depending on e.g. the cable type etc) 

  1. Whatever value is given to DLM group, the stations' minimum and maximum values are always respected. If the station's minimum requirement is 5 kW and a maximum 11 kW, the DLM-group's settings will never overrule these values  


Is DLM supported with AC and DC devices? 

Virta DLM is compatible with both AC and DC chargers. Please see the question: What hardware requirements are there to take into account?


What if the chargers lose their internet connection? 

In the event that the internet connection is lost, the previously set current limits for all stations on the site are preserved. Therefore, the total maximum site current consumption is kept at the set limit. 


What hardware requirements are there to take into account? 

In order to utilize Virta’s DLM solution, the devices must be OCPP 1.6-J compatible and support charging power adjustments during charging 

DLM 2.0 specific questions 


What is DLM 2.0? 


DLM 2.0 introduces an external measuring unit that enables monitoring of all loads on the site, e.g. building and all its consumers. By monitoring all loads on the site, it is possible to determine how much electrical current there is available. The available dynamic capacity can be allocated for e.g. charger sites. This makes it possible to create a rule that if there is not enough dynamic capacity to meet the static limit set for the charger site, the maximum limit is decreased during times of high consumption. Charging occurs at a full volume when there is enough dynamic capacity available. With DLM 2.0 it is possible to make the most out of the site's main connection without upgrading the hardware and installations.  


What's the difference between DLM Fixed Capacity (1.0) and Variable Capacity (2.0)? 

DLM 2.0 takes into account the whole site’s consumption and adjusts the charger group’s charging power based on available capacity. With DLM 1.0, the charger group is set with a static limit, which does not dynamically change based on external signals.  


Does DLM receive information from local power meter about actual grid consumption? 

Yes, with the solution where DLM Management Unit (= local meter supported by Virta) has been installed at grid connection point.  


How does the DLM Management Unit work? 

The DLM Management Unit (= external measuring unit) is installed at the grid connection point to measure all the site’s loads. The unit’s power meter is attached to all the main supply’s phases with current clamps in order to measure the loads. A cloud gateway then sends the measurements to Virta’s cloud service via 3G connection. This data together with meter values from the chargers is used for recalculating available charging power. 


How often are the recalculations done and delay of control? 

The measurement-recalculation cycle for available charging power is about 5 seconds. The time from receiving values from the DLM Management Unit to the moment when chargers accept new requests vary but it is usually from 10 to 20 seconds.


What happens if DLM Management units loses its internet connection? 

In case that the connection is lost to the external current measurement device, the charger group’s charging power will be limited to a defined safe level until the connection is re-established. 


Do you have any energy management solution for local use (without internet connection)? 

If the site is known for very poor or intermittent internet connection, there is also possibility to operate non-cloud -based charging point specific hardware DLM in conjunction with the Virta platform. However, this approach restricts the use of different charger brands at the same charging site and requires additional cabling.  


How are different phases taken into account with DLM 2.0? 

DLM 2.0 can be setup with two different ways:  


  1. All three phases are monitored and the highest value from all three phases is used for calculating available charging power 

  1. A single phase is selected and the value provided by this phase is used for calculating available charging power