What is PLC?
Power line communication (PLC) is a communication method that uses the local power grid (230V) to provide an internet connection to other Power line devices (such as Zaptec Pro charging stations). The PLC module converts a standard Ethernet connection (network cable) into a signal sent over the local power grid (power line), removing the need for separate network cables to each charger.
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Watch: PLC theory overview.
The video uses a standard domestic PLC adapter. For best result, use the Zaptec-supplied DIN-rail PLC module.
Requirements and best practices
To ensure reliability:
- Minimum one PLC module per circuit.
- Each PLC module can support up to ~30 chargers.
- Ensure the protective earth (PE) is in good condition.
- Zaptec Pro is wired 3-phase, but the PLC module should always be wired 1-phase (L1-N-PE). Charging stations communicate on PLC over L1 and N.
- Maintain the same phase order across the entire charging system.
- If the cable run is long, you may need multiple PLC models on the same circuit to maintain signal strength.
- Install the PLC module in an enclosure close to the charging stations, preferably in the middle of the installation for even signal distribution.
- The cable length must never be more than 90 meters.
- Remove or isolate noise sources from the network.
- Do not connect the PLC three-phase or to L2, L3, as this increases cable length and reduces signal strength.
Long distances can impact the signal. The recommended cable length may vary depending on grid type, number of chargers, and noise from the power grid. For example, IT systems require shorter cable runs than TN systems.
How to install the PLC module
Zaptec Pro is wired 3-phase, and the PLC is wired 1-phase. If the PLC modules are fully encrypted, configure the charging stations as described in the procedure supplied with the PLC module. In the table below, you can see installation diagrams for TN and IT/TT grids.
- Mount the PLC module on a DIN rail, close to the charging stations, preferably in the middle of the installation for even signal distribution.
- Connect to the main power cabling and a standard Ethernet cable.
- It is recommended to install a 10A fuse before the PLC module.
- The module is usually mounted after a 63A course, but the connection terminals are 1.5-2.5 mm². This also simplifies any troubleshooting and restart of the PLC module.
Wiring diagrams
Connection TN system Connection IT system
PLC module configuration
After the PLC is mounted, connect the charging stations to the PLC network using the Zaptec App.
Modules purchased after Nov. 2019 come pre-encrypted with a QR code.
Modules purchased before Nov.2019 require manual key entry.
Steps (repeat for each charging station)
- Open the Zaptec App and tap the three-dot icon (top-right).
- Select Configure products and connect via Bluetooth using the PIN code.
- Go to Network Settings > Configure PLC.
- Tap the Scan network name and use the camera to scan the QR code on the PLC module. (iPhone users can upload images from the gallery).
- Tap Save to connect.
Use the existing network key to add another charging station:
- Open the Zaptec App and tap the three-dot icon (top-right).
- Select Configure products and connect via Bluetooth using the PIN code.
- Copy the network key from an online charging station.
- Follow the same procedure on the new charging station and paste the network key in the last paragraph under Set network key. Remember to tap Save.
PLC module indicator light
| Icon | Color | Status |
|---|---|---|
| Green | PLC is connected to power | |
| No Light | PLC is not connected to power | |
| Red | PLC communicates with charger(s) | |
| Green | PLC is not communicating with other units on the PLC network. This could be because the chargers are not encrypted with the same encryption key as PLC | |
| Green | PLC is connected to network router | |
| No Light | PLC is not connected to open port on router. Even though it is communicating with router, it does not mean it has access to the internet. |
Troubleshooting
Factors that can affect the signal strength of the PLC network:
Cable length
- Cable length has a direct effect on the signal strength of the charging stations.
- Use minimum one PLC unit per cable run/course.
- Place the PLC module close to the charging stations, especially if the supply from the switchboard is far away.
- The charging stations communicate with the PLC only between L1 + N + PE.
- Connection on the L2 and L3 terminals will lead to increased cable length the devices are trying to communicate.
Number of connected devices
- A PLC module has a limit on the number of devices it can communicate with. The general recommendation is 30 charging stations per PLC module. Exceeding this number will lead to unstable communication over the PLC.
- Isolate PLC communication on each course by encrypting the PLC module and associated charging stations.
- Minimum one PLC unit per cable run/course.
Grounding conditions
- PLC communication uses the ground connection for positioning the frequency range. Poor grounding reduces range and stability.
- If the ground connection is insufficient or affected by external factors like ground faults, this may result in the PLC not being able to maintain sufficient signal quality for stable communication.
Electrical noise and local power outages
- Noise from external sources, like frequency converters, can disrupt PLC signals.
- It can be difficult to map, but this can be limited by installing a filter before the PLC module.
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