Energy Meter VM-3P5A – flexibly measure high currents – with 5A current transformers
3-phase | Ethernet & VE.Can | Flexible configuration | for ESS, PV inverters, generators & AC loads | easy setup
The Victron VM-3P5A measures power and energy in single-phase, three-phase and split-phase AC systems, enabling reliable monitoring of different energy flows.
With the VM-3P5A, Victron expands its range with the “big brother” of the proven VM-3P75CT. While the VM-3P75CT works exclusively with the supplied current transformers and measures currents of up to 75A per phase, the VM-3P5A is designed for use with industry-standard 5A current transformers, making it particularly suitable for larger systems and higher currents.
By selecting suitable 5A current transformers, the measuring range can be flexibly adapted to the respective system. Depending on the transformation ratio of the current transformers used, currents of theoretically up to 6,000A per phase can be measured. This provides a suitable solution for applications above the measuring range of the VM-3P75CT.
Typical applications include measurement at the distribution board, measuring the power of a PV inverter, generator, inverter or inverter/charger, as well as use as a grid meter within an ESS system. AC loads can also be monitored with the energy meter.
For integration into the Victron system, the VM-3P5A features Ethernet and VE.Can. Functionally, it is based on the VM-3P75CT, but the use of standardised 5A current transformers provides significantly greater flexibility when designing higher-power systems.
Features:
- Suitable for three-phase, two-phase and split-phase wiring
- Ethernet & VE.Can
- supports industry-standard 5A current transformers (not included)
- configurable energy measurement
- monitoring of electrical parameters
- status LED
- high update rate
- easy setup (Plug & Play)
What can the VM-3P5A be used for?
In combination with a GX device such as the Cerbo GX MK2 or Ekrano GX, the VM-3P5A offers flexible application options. Depending on the configuration, it can perform various roles and provides the required measurement values for monitoring, analysis and system control:
- Can be used as a grid meter and as a control input for an ESS system. The energy meter measures the energy flow at the grid connection point and provides the measurement values for controlling and monitoring the ESS system.
- For measuring the power of a PV inverter. This allows the AC power supplied by the PV inverter to be measured, displayed and analysed within the system.
- For measuring the power of an AC generator. This allows the energy supplied by the generator to be included in the system monitoring.
- As an AC meter for measuring the AC output of an inverter or inverter/charger. This allows the supplied power and energy flows on the AC side to be monitored.
Note: The VM-3P5A has no integrated fuse. Therefore, external overcurrent protection must be installed at each of the four voltage measurement inputs: N, L1, L2 and L3. A 500mA fuse is required at each input.
When is the VM-3P75CT the right choice and when the VM-3P5A?
For typical applications in your home, the VM-3P75CT is generally the simpler and entirely sufficient solution. It can measure currents of up to 75A per phase and is supplied with the appropriate current transformers. This means you do not have to select additional current transformers or match them to the measuring range of your system.
The VM-3P5A is primarily suitable for larger commercial or industrial systems where currents above 75A per phase need to be measured, the measuring range needs to be individually adapted, or existing 5A current transformers are to continue to be used. It works with external 5A current transformers selected to suit the respective system. These measure the actual current flowing in the system and provide the VM-3P5A with a standardised measuring current of up to 5A. Depending on the transformation ratio of the current transformer used, significantly higher currents can therefore also be measured.
In short: For typical home systems and a straightforward complete solution, the VM-3P75CT is usually the right choice. For higher currents and individually adjustable measuring ranges, the VM-3P5A is recommended.
How do 5A current transformers work with the VM-3P5A?
The VM-3P5A works with industry-standard 5A current transformers. These measure the actual current flowing in the system and reduce it to a standardised measuring current of up to 5A. The energy meter evaluates this measuring current and uses it to determine the actual current in the system.
The 5A value is not the maximum measurable current of the system, but rather the standardised secondary current of the connected current transformer. Depending on the transformation ratio used, significantly higher currents can therefore be measured, for example with 100A/5A, 500A/5A or 1,000A/5A current transformers. This allows the measuring range to be flexibly adapted to different system sizes and current levels.
Note on using the current transformer:
The primary current set in the energy meter must correspond to the transformation ratio of the current transformer used. The information on the current transformer's rating plate is decisive. For example, for a current transformer marked 250/5A, a primary current of 250A must be set in the energy meter. If the transformation ratio is not stated directly on the current transformer, refer to the manufacturer's technical documentation.
Operation and communication of the Energy Meter VM-3P5A
The Energy Meter calculates the RMS power values for each phase and transmits them at a high rate via VE.Can or Ethernet, enabling more accurate measurements of power consumption, grid import and grid feed-in, for example in an ESS system. The VM-3P5A uses the vector registration method (the vectors of the individual phases L1, L2 and L3 are summed).
For connection to a GX device, for example a Cerbo GX MK2 (as shown here in the illustrations), the VM-3P5A offers two flexible options: VE.Can or Ethernet. If a local network is already available and the GX device is connected to it via Ethernet or Wi-Fi, the energy meter can simply be connected to the same network via Ethernet. (left illustration)
Alternatively, the VM-3P5A can be connected directly to the GX device via the VE.Can ports. The VE.Can network must be correctly terminated at both ends using the supplied terminators. (right illustration)
For both connection methods, the use of a high-quality Ethernet cable is recommended, such as a 1.8m Victron RJ45 UTP cable, which is available in various lengths.
How is the VM-3P5A configured and monitored?
When using a VE.Can connection, the VM-3P5A is automatically detected as soon as it is connected to the VE.Can port and properly terminated. Please ensure that the VE.Can profile of the GX device's VE.Can port is set to 250 kbit/s.
When using an Ethernet connection, the VM-3P5A regularly broadcasts mDNS data, which is automatically detected by the GX device.
There are two ways to connect to the VM-3P5A via VictronConnect from a mobile device, laptop or PC:
- Directly via Ethernet using the Modbus/UDP connection on the local network
- Or remotely via VictronConnect-Remote (VC-R), either via VE.Can or Modbus/UDP (requires the GX device to be connected to the VRM portal).
The VM-3P5A supports instant display of important data (total power and power per phase) directly from the device list in VictronConnect. This works via a local network connection and VictronConnect-Remote (VC-R).
General examples of AC wiring for the Energy Meter VM-3P5A
Scope of delivery
- Victron Energy Meter VM-3P5A | REL200320100 | Energy meter
- 2 x VE.Can RJ45 terminators
- Of course, you will also receive an operating manual in English from us in the download area.
Victron manufacturer's warranty
- Lithium batteries: 3-year manufacturer's warranty
- Lead/Gel/AGM batteries: 2-year manufacturer's warranty
- All other products: 5-year manufacturer's warranty, extendable to 10 years
Frequently asked questions about the Energy Meter VM-3P5A (FAQ)
Why does the current value seem unusually high for the displayed power?
The energy meter calculates the active power of each phase (P, in watts), which is shown on the display. Active power is determined by:
- Single-phase system: P = Voltage × Current × Power factor (cos θ)
- Three-phase system: P = √3 × Voltage × Current × Power factor (cos θ)
If the power factor is equal to one (cos θ = 1), the active power equals the apparent power (S), which is simply calculated from RMS voltage × RMS current.
In most real-world systems, inductive and/or capacitive loads cause reactive power. This results in a reduction in the power factor, meaning that the apparent power (S) becomes higher than the active power (P).
In AC systems, it is therefore normal and expected for the apparent power (S) to be higher than the active power (P) when the power factor is below 1.
The VM-3P5A also reports the power factor directly. If the current appears unusually high compared with the power value, please check the displayed power factor: a low value confirms that reactive loads are the cause.
Examples of an unfavourable power factor:
- Small electronic devices such as USB chargers and LED lighting often have a particularly poor power factor.
- Renewable energy generation systems, on the other hand, are legally required to operate with a power factor close to 1. This can exaggerate the difference between P and S, because the “good” power factor from generation is cancelled out, leaving only the “poor” factor from the loads.
Possible solutions:
- Please use loads with integrated power factor correction (common in modern PC power supplies).
- Alternatively, you can consider installing dedicated power factor correction equipment.
Did the firmware update via the Ethernet connection fail?
If you experience problems updating the VM-3P5A firmware via Ethernet, try connecting the device to the GX device via VE.Can (see the operating manual – section Ethernet and VE.Can wiring [7] for details), perform the update again as described in the Firmware updates chapter [11], and then reconnect via Ethernet.
