# Load management

> Load management in the Voltmasters EMS: limits per energy meter on top of the grid connection limits, with per-phase protection and the order in which the EMS intervenes.

Source: https://voltmasters.io/en/docs/voltmasters-platform/device-management/device-settings/load-management/

Load management keeps the power flowing through an **energy meter** below limits you set. It is configured per meter, on the meter’s **Load Manager** tab.

The limits of the grid connection itself are set in the [project settings](https://voltmasters.io/en/docs/voltmasters-platform/project-settings/general-settings/), with the access power and the [peak shaving reserve](https://voltmasters.io/en/docs/control-algorithms/peak-shaving-reserve/). Load management adds limits on meters deeper in the installation.

The limits of the grid connection itself are set in the [project settings](https://voltmasters.io/en/docs/voltmasters-platform/project-settings/general-settings/), with the access power and the [peak shaving reserve](https://voltmasters.io/en/docs/control-algorithms/peak-shaving-reserve/). Load management adds limits on meters deeper in the installation.

| Setting | Description |
| --- | --- |
| **Enable Load Management** | Switches load management on for this meter. |
| **Maximum injection power** (kW) | The highest power the installation behind this meter may feed back. |
| **Maximum consumption power** (kW) | The highest power the installation behind this meter may draw. |

![The Load Manager tab on an energy meter with the Enable Load Management switch and the fields Maximum injection power and Maximum consumption power, both at 150 kW.](https://voltmasters.io/assets/docs/load-management-meter.webp)

## Limits across the whole metering hierarchy

Every meter can carry its own limits, and the EMS enforces them **all at the same time**, together with the limits of the grid connection. A **sub-meter** protects what sits behind it, such as a transformer, a distribution board, a cable or a single building, even when the grid connection still has room. A busy sub-circuit is throttled without slowing down the rest of the site.

```mermaid
flowchart TD
    N["Grid"] --- H["Main meter: grid connection limits"]
    H --- A["Sub-meter building A: own limit"]
    H --- B["Sub-meter charging area: own limit"]
    A --- V["Loads in building A"]
    B --- E["EV chargers"]
```

Every meter has its own limit, and the EMS watches all of them at the same time.

## Unevenly loaded phases: per-phase protection

The limits are set in kW for the connection as a whole, but on a three-phase connection the fuses and the connection rating are **per phase**. When the phases are loaded unevenly, the total can be well below the limit while one phase is already over its share, and it is that single phase that trips the main breaker.

When the meter measures its power **per phase**, the EMS therefore protects each phase as well. It does so **pessimistically**: every limit check treats the site as if all three phases carried the same load as the heaviest one.

```mermaid
%%{init: {"xyChart": {"height": 300}, "themeVariables": {"xyChart": {"plotColorPalette": "#f8b81e, #0a0a0a"}}}}%%
xychart-beta
    x-axis ["L1", "L2", "L3"]
    y-axis "kW per phase" 0 --> 10
    bar [4.5, 8.5, 4.5]
    line [7.33, 7.33, 7.33]
```

A 22 kW limit: the bars are the load per phase, the line is the share of the limit per phase (22 kW ÷ 3 ≈ 7.3 kW).

In this example L1 and L3 each draw 4.5 kW and L2 draws 8.5 kW. The total of 17.5 kW stays under the 22 kW limit, but L2 is over its 7.3 kW share. The EMS therefore counts 3 × 8.5 = 25.5 kW, more than 22 kW, and reduces the load until L2 fits.

## What the EMS does when a limit is approached

When the power measured by a meter approaches its limit, the EMS intervenes, from the least disruptive measure to the most. It does so in this order:

1.  **The battery**: charging is reduced or stopped and, if needed, the battery **discharges** to take load off the meter.
2.  **EV charging**: the charging power of the [EV chargers](https://voltmasters.io/en/docs/control-algorithms/ev-charging/) behind that meter is curtailed.
3.  **Controllable loads**: [on/off loads](https://voltmasters.io/en/docs/device-integrations/controllable-loads/) are switched off one by one, in the order of their **Priority**.

Only when a step cannot free up enough power does the EMS move to the next one, so equipment is switched off as a last resort.