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MultiPlus-II External Transfer Switch application

4. Configuration

In this section:

4.1. Upgrade to S99 VE.Bus firmware

The MultiPlus-II units require application-specific VE.Bus firmware, identified by the “.S99” subversion number.

Upgrade procedure:

  1. Download the xxxyy.S99.vff file from https://professional.victronenergy.com/

  2. Install the firmware using VEFlash, the VictronConnect app, or the VRM Portal.

  3. Ensure you select the xxxyy.S99.vff file during the firmware upgrade.

  4. Repeat the process for all MultiPlus-II units.

Caution

CAUTION: Never use MultiPlus-II unit with standard firmware in an "External transfer switch" application. This will cause the system to connect to the AC input and likely trigger the current protection on that measurement-only circuit.

4.2. VE.Bus System configuration

Use the "VE.Bus System Configurator" to set up the system.

Configuration procedure

  1. Configure all phase masters in AC input group 1.

  2. Configure all slaves in AC Input Group 2.

Refer to the following screenshots.

MultiPlus-II_external_transfer_switch_-_VEbus_config_1.png
MultiPlus-II_external_transfer_switch_-_VEbus_config_2.png

4.3. MultiPlus-II configuration

Use "VEConfigure" to configure each MultiPlus-II unit.

Configuration procedure:

  1. Ensure the “S99” firmware version is installed

  2. Navigate to the “General” tab.

  3. For all phase master units, set the "Current sensor rating" to 100 or 400A, matching the current sensor's current rating.

  4. For all slave units, set the "Current sensor rating" to 100A, regardless of the current sensor's current rating.

  5. Navigate to the "Grid" tab.

  6. For all units, set the "Country/grid code standard" to "None".

Refer to the following screenshot.

MultiPlus-II_external_transfer_switch_-_VE_configure.png

4.4. Venus OS version

If a GX device is used, it should be updated to Venus OS version 3.33 or later.

4.5. GX device generator start/stop feature.

For a seamless transfer, we recommend using the generator start/stop feature in our GX devices, including the cool-down function,

Here is how it works:

When the system receives the signal to stop the generator, the inverter first takes over the load. Only after this and after the configured cool-down period will the generator stop. This makes the exact opening time of the contactor irrelevant, ensuring an instant (0 ms) transfer with no interruption.

In contrast, stopping the generator first and allowing the inverter to initiate the transfer after it has detected a drop in voltage or frequency will result in a slower changeover, regardless of contactor speed.

For more details on the GX generator start/stop feature and integration with DSE, ComAp, and other generator controllers, see Chapter 17 of the GX manual.