victron energy MultiPlus-II External Transfer Switch User Manual

August 30, 2024
victron energy

MultiPlus-II External Transfer Switch

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Product Information

Specifications

  • Model: MultiPlus-II external transfer switch manual
  • Revision Date: 2024-06-20
  • Compatibility: Generator-based systems only
  • Required Firmware: VE.Bus firmware, version S99
  • Additional Hardware:
    1. High current 4 pole contactor
    2. Ground relay: High current single pole relay
    3. Relay Rated for 230V with 24V Coil

Product Usage Instructions

Installation

To install the external transfer switch, follow these steps:

  1. Ensure you have the required firmware version installed.

  2. Acquire the necessary additional hardware listed in the
    specifications.

  3. Use a Schneider LC1G3304 TeSys Giga, 4-pole (4NO), AC-1 for the
    external transfer switch.

Configuration

To configure the system using an external contactor, follow
these guidelines:

  1. Refer to the wiring diagram in the manual for proper
    connections.

  2. Make sure to check the single line diagram provided in the
    appendix for full-size connection diagrams.

  3. Double-check the wiring before powering up the system to avoid
    damage to the MultiPlus-II units.

FAQ

Q: Can this external transfer switch be used with grid-tied

systems?

A: No, this solution is intended for generator-based systems
only and is not certified for use with grid-tied systems.

Q: What should I do if I encounter wiring issues during

installation?

A: If you experience wiring problems, it is recommended to seek
assistance from trained professionals to avoid damaging the
MultiPlus-II units.

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MultiPlus-II external transfer switch manual
Contents
Introduction ……………………………………………………………………………………………………………. 2 Requirements and compatibility ……………………………………………………………………………… 2 Additional hardware requirements …………………………………………………………………………… 2 Single line diagram………………………………………………………………………………………………… 3 Warnings …………………………………………………………………………………………………………….. 3
Installation ……………………………………………………………………………………………………………… 4 External transfer switch………………………………………………………………………………………….. 4 Ground relay ………………………………………………………………………………………………………… 4 Current transformers …………………………………………………………………………………………….. 4 AC Wiring…………………………………………………………………………………………………………….. 5
Wiring diagram ………………………………………………………………………………………………………… 6 Configuration ………………………………………………………………………………………………………….. 6
VE.Bus System Configurator …………………………………………………………………………………… 6 VE Configure………………………………………………………………………………………………………… 8 Venus OS…………………………………………………………………………………………………………….. 8 Troubleshooting ………………………………………………………………………………………………………. 9
Revision 3 2024-06-20

Introduction
This manual explains how to install and configure a system using an external contactor (transfer switch) instead of the Multiplus-II built-in relays.
Using an external transfer switch reduces wiring costs and installation time.
This solution is intended for generator-based systems only and cannot be used with grid-tied systems as it is not certified for such use.

Requirements and compatibility

· Compatible with all MultiPlus-II models rated 5000VA and above.

· Maximum number of units is 12, 4 per phase. Maximum systems size is this 180kVA.

· Only one AC input source is supported

· Current transformer and contactor rating of 100A or 400A.

·

Requires application-specific VE.Bus firmware, version S99.

Additional hardware requirements
1. High current 4 pole contactor: The external transfer switch. 2. Ground relay: High current single pole relay. 3. Relay Rated for 230V with 24V Coil: A relay with these specifications is necessary for
controlling the ground relay. The 24V coil allows it to be activated by the lower voltage control circuit inside the MultiPlus-II. 4. Victron Current Transformer: This component measures the current in a circuit and is essential for monitoring and managing power usage accurately. 5. 1.5 mm² wire and four- pole circuit breaker: This ensures that the whole circuit is protected.
See the installation chapter for details.

Single line diagram
See the appendix for the full-size connection diagrams.
Warnings
Parallel and Multiphase systems are complex. We do not support or recommend that untrained and/or inexperienced installers work on these size systems. Double-check the wiring before the system’s initial power-up. Wiring mistakes can damage the MultiPlus-II units.

Installation
External transfer switch
Use a Schneider LC1G3304 TeSys Giga, 4-pole (4NO), AC-1 <=440V 440A contactor Connect the coil directly to the NO and COM terminals of the MultiPlus-II “AUX RELAY” of the L1 phase master unit.
Do not use a different contactor, as closing and opening times differ per brand and model.
Ground relay
The ground relay drive signal is supplied by the MultiPlus-II “Ext GND Relay” terminals of the L1 phase master unit. The “Ext GND Relay” output signal is limited to 24V / 200mA, so an extra relay with a 24V coil that switches the actual ground relay must be installed. The ground relay rating must match the total inverter power of the system.
Current transformers
Connect the current transformers for L1, L2, and L3 to the “Current Sense” inputs on the respective phase master MultiPlus-II units. Remove the wire bridge between the INT and COM terminals. Connect the red sensor wire to the EXT terminal and the white sensor wire to the COM terminal. Ensure the wire direction through the current sensor follows the arrow pointing towards the Multi. To prevent signal interference, avoid routing current sensor wiring parallel and close to AC power wiring. This applies to all signal wires, including the VE.Bus cables. Note that the higher rating of 400A sensors reduces current sense resolution, especially at low currents.

Compatible current transformers:
· CRT12xxxx Current Transformer 100A:50mA for MultiPlus-II Wire-end (available in 1.5 and 20m cable length)
· CTR140050100 Current Transformer 400A:50mA for MultiPlus-II (10m) Wire-end (the current sensor wiring can be extended up to 20m using 0.75mm2 wire)
· CRT11xxxx Current Transformer 100A:50mA for MultiPlus-II Jack connector (for older MultiPlus-II units, available in 1.5 or 20m length)
For further details: https://www.victronenergy.com/meters-and-sensors/current- transformer-formultiplus-ii.
AC Wiring
In this application, inverter current flows through the AC outputs of the MultiPlus-II units, so the external transfer contactor wiring diameter must be appropriately sized and symmetrical.
Protect the AC output wiring with a circuit breaker suitable for the expected load and wire gauge. Fuse both line and neutral wiring.
The wiring to the AC inputs of the phase masters acts as measuring/sense wires. Since the Multi firmware will not drive its internal back-feed relay, these wires can be relatively thin, such as 1.5mm². Fuse the line and neutral wires using 6A four-pole circuit breaker.
Leave the AC inputs on slave units unconnected.

Wiring diagram
AC input
(See full size diagrams in the appendix)
Configuration
Install S99 VE.Bus firmware
The external transfer switch application requires special VE.Bus firmware, identified by the “.S99” subversion number. Download the xxxyy.S99.vff file from https://professional.victronenergy.com/ Install it using VEFlash, the VictronConnect app, or via the VRM Portal. Make sure to select the xxxyy.S99.vff file. Note: never update or upgrade systems with “External transfer switch” firmware using standard VE.Bus firmware, as this will cause the system to connect to the AC input and likely trigger the current protection on that measurement-only circuit.
VE.Bus System Configurator
Use the “VE.Bus System Configurator” to set up the system. Configure all phase masters in AC input group 1 and all slaves in AC input group 2, as illustrated in the following screenshots.

VE Configure
Use “VEConfigure” to select the correct current sensor rating for the L1, L2, and L3 phase masters (keep the sensor rating in the slaves at 100A). With the correct “S99” firmware version, this setting is located in the “General” tab, as shown below. Currently, 100A and 400A current sensors are supported. For all connected MultiPlus-II units, configure the grid codes in the “Grid” tab to be the same. Select “None” as the grid code.
Venus OS
If a GX device is used, it should be updated to Venus OS version 3.33 or later.

Troubleshooting
If the system exhibits strange behavior, check the following:
· Ensure the orientation of the current transformers is correct; the arrow on the CT should align with the direction of the arrow in the drawing: points from generator to the contactor.
· Verify the location of the current sensors: L1 should connect to the L1 unit, L2 to the L2 unit, and so on.
· Ensure the current sensor wires are not routed too close to AC or signal wires.
Known issues:
· The VRM kWh counters may show incorrect readings; this will be fixed in an upcoming version of Venus OS.
· The VictronConnect app cannot be used for system configuration and current sensor settings. Use VE.Configure and VE.Bus System Configurator instead.

External transfer switch conceptual diagram

Generator

AC measurement wiring, connected to the AC-in terminals
External transfer switch

VE.Bus

VE.Bus

Power wiring, connected to The AC-out terminals

CTs & voltagemeasurements

Loads
Rev 1.1

Detailed wiring

Input voltage and current measurement

N L1 CT-L1

L2 CT-L2

B

B

F

L3 CT-L3 B

To input voltage and current measurement

A N L1 L2 L3

CT coils

4p Breaker (6A)

N

Generator

L1 L2

L3

D

2A

Optional

E

2A

4p Breaker and RCD

C

Loads

A 1.5mm2 AC measurement wires, connected to the MultiPlus-II AC input terminals B Current transformers for MultiPlus-II. Route wires through in the direction of the arrow pointing towards the main contactor C External transfer switch with 230Vac coil, driven by the MultiPlus-II programmable relay D Help relay, driven by the external ground relay output of the MultiPlus-II. (24V, 200mA max) E Ground relay F Additional MultiPlus-II units can be paralleled in each phase with only their AC outputs and the VE.Bus cables connected

References

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