victron energy MultiPlus-II External Transfer Switch User Manual
- August 30, 2024
- victron energy
Table of Contents
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:
- High current 4 pole contactor
- Ground relay: High current single pole relay
- Relay Rated for 230V with 24V Coil
Product Usage Instructions
Installation
To install the external transfer switch, follow these steps:
-
Ensure you have the required firmware version installed.
-
Acquire the necessary additional hardware listed in the
specifications. -
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:
-
Refer to the wiring diagram in the manual for proper
connections. -
Make sure to check the single line diagram provided in the
appendix for full-size connection diagrams. -
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