Installation only by the specialist!

All persons involved in the commissioning,
maintenance and maintenance of the device must:
  • be appropriately qualified
  • have knowledge of the handling of electrical installations
  • Read and understand this manual completely
  • The installation information in this manual is only for qualified persons
    Professional staff
  • Never try to repair the unit yourself! An electric shock can be deadly!
  • Its not allowed to use the board without housing

For more!

Further information can be found at:
In addition, the open source software is constantly being further developed.
You can find the project page on Github:

The SmartPi 3.0 expansion module

SmartPi 3.0 Erweiterungsplatine
Abbildung 1: SmartPi 3.0 Erweiterungsplatine



Figure 1 shows the SmartPi 2.0 expansion module. The SmartPi 2.0 expansion module enables non­contact current measurement via inductive current sensors with the RaspberryPi. The SmartPi 2.0 expansion module can also be used to measure the voltage and extend the Raspberry Pi to a fully­ fledged SmartMeter.
The SmartPi 2.0 expansion module has 4 inputs for connecting inductive current sensors and 3 inputs for voltage measurement. The system is supplied with the required operating voltage via the L1 voltage connection. A separate power supply is not required.

A relay for switching, an RS485 connection and an integrated RTC enable the connection of further devices and enable the measuring operation also without an Internet connection.

Connecting SmartPi 3.0 to the Raspberry Pi

Anschlussleiste SmartPi 3.0
Abbildung 2: Anschlussleiste SmartPi 3.0

The SmartPi expansion module is connected via the GPIO port of the Raspberry Pi. The easiest way to connect is via a 26-pin ribbon cable.

The power supply for the Raspberry Pi is provided by the SmartPi expansion board. A power supply unit for the Raspberry Pi is therefore not required.
Figure 2 shows the designation of the connections used.

SmartPi RaspberryPi
+5V 5V / PIN2 / PIN4
D0 GPIO 23 / PIN16

Einstellung der Stromwandler

Jumpereinstellung für die Auswahl des richtigen Sekundärstroms
Abbildung 3: Jumpereinstellung für die Auswahl des richtigen Sekundärstroms

The SmartPi 3.0 is suitable both for the connection of 50mA secondary current transformers (for example SCT013­000), as well as for the connection of current transformers with a secondary current of 1A. Set the secondary current according to your current transformers.


Too high current can damage the ADC converter of the SmartPi. Therefore, never use a transformer with to high current at the SmartPi. Also make sure that a current transformer is operated with the maximum rated current only.

Assembly of the SmartPi 3.0

From above, screw the screws through the circuit board into the spacer bolts....

First attach the spacer bolts to the Raspberry Pi. Hold the spacer bolts against the board of the Raspberry Pi from below....

Plug the 26-pin ribbon cable onto the pin header of the SmartPi. Please make sure that the lead points towards the battery. Attach the Raspberry Pi to the SmartPi.

Then plug the ribbon cable onto the pin header of the Raspberry Pi.

The next step is to insert the clips for the bracket from the inside to the outside.

To mount the SmartPi in the housing, please place the electronics in the housing. Make sure that the connections fit exactly.

Then put on the lower shell and press it down. It may help to push the lugs apart a little with your fingernails.

Plug the connectors onto the sockets from the outside.

...then insert the SD card with the operating system.
The installation is finished.

Connection of the current and voltage measurement

Anschlussschemata der Strom und Spannungsmessung
Abbildung 4: Anschlussschemata der Strom und Spannungsmessung
Anschluss des SCT013­-000
Abbildung 5: Anschluss des SCT013­-000

To connect the current measurement, the conductors of the individual phases are led through the current sensors. With folding transformers, installation is very simple.
Please note that a possibly existing arrow on the transformers represents the reference direction. The "positive" connection is led to the right-hand pole of the connection terminal. Reversing the polarity of the connection leads is not a problem, but will result in an incorrect representation of the reference and the connection.

With the SCT013-000 current sensors (supplied), the red connection lead must be connected to the right (Figure 5).
The measuring voltage is connected to the voltage connections. Make sure that L1 is on the right and neutral N is on the left. Be careful not to reverse the polarity of the connections.

You can also use the SmartPi without voltage measurement.

To do this, you can preset a voltage in the software settings that the SmartPi uses to calculate the power. Note that in this case the power measurement is only possible to a limited extent (no bidirectional measurement, only apparent power, no cos Phi, no power factor).

Excursus on current measurement

The SmartPi measures the electrical current in the same way as a current clamp meter in an indirect way. One advantage is that the circuit does not have to be disconnected and the measurement is contactless.
The current I flowing through the conductor generates a magnetic field H which runs in a ring around the conductor (Figure 7).
The current is measured according to the transformer principle with the conductor as the primary winding and the current sensor as the secondary winding.
If a current sensor is now placed around the conductor, the magnetic field of the conductor induces a current in the current clamp that can be measured (Figure 6).
If current flows through two conductors in opposite directions, the resulting magnetic field is cancelled out because the two magnetic fields are directed in opposite directions (Figure 8).
The current sensor can't measure current.

Phase and neutral conductor must not be connected together through one current terminal.
If the consumption of an electrical appliance (e.g. television)  to be measured, the individual conductors in the supply line must be separated. The current clamp has only to be placed around the conductor in which the current flows into the device.
If the current sensor is placed around the entire supply line, the SmartPi cannot measure consumption.

Principle of the current clamp for alternating current
Figure 6: Principle of the current clamp measurement for alternating current (Source: Wikipedia (©CC BY-SA 2.0 de))
Magnetic field around a current-carrying conductor
Figure 7: Magnetic field around a current-carrying conductor
If current flows through two conductors in opposite directions, the total magnetic field is cancelled out.
Figure 8: If current flows through two conductors in opposite directions, the total magnetic field is cancelled out.