Installation only by the specialist!
- 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
- Never try to repair the unit yourself! An electric shock can be deadly!
- Its not allowed to use the board without housing
The SmartPi 3.0 expansion module
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
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.
|SDA||SDA / PIN3|
|SCL||SCL / PIN5|
|MOSI||SPI0_MOSI / PIN19|
|MISO||SPI0_MISO / PIN21|
|SCLK||SPI0_CLK / PIN23|
|+5V||5V / PIN2 / PIN4|
|D0||GPIO 23 / PIN16|
|EXT_INT||GPIO 24 / PIN16|
|CS_EXT||SPI0_CE1_N / PIN26|
Einstellung der Stromwandler
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
Connection of the current and voltage measurement
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.