When working on substation and photovoltaic grid-connected cabinet projects, equipment manufacturers often encounter a common situation: the electricity meters, protection devices and communication management machines inside the cabinet have all been commissioned, but the on-site deployment gets stuck at the "network access" step.

Some old station buildings do not have ready-made network conditions, and re-laying optical fibers incurs high costs; distributed photovoltaic project sites are widely scattered, and most of them can only rely on 4G access. In addition, strong and weak current devices are concentrated inside the grid-connected cabinet, and the operation of switches and inverters will further complicate the on-site electromagnetic environment. Once the communication becomes unstable, the background will fail to view real-time data such as real-time power, switch status and fault alarms.

In this type of project, the core task of the industrial 4G router is not "data collection", but to transmit the pre-collected data inside the grid-connected cabinet to the remote monitoring platform stably and securely.

1. Problems That Need to Be Solved
1.1 Network Convergence of Multiple On-Site Devices

A typical grid-connected cabinet may be equipped with an energy meter, protection and measurement control device, PLC, communication management machine and video monitoring equipment. The current official specifications of the G809s provide 8 Gigabit RJ45 electrical ports and 2 SFP optical ports, along with RS232 and RS485 interfaces, which reserve sufficient access resources for different types of devices inside the cabinet.

For manufacturers, this means that the communication part can be planned uniformly during the cabinet design phase, eliminating the need to temporarily add network equipment at each project site.

1.2 Solve the Instability of Site Uplink Network

Substations with favorable conditions can access the monitoring center through wired or optical fiber connections; distributed photovoltaic systems and remote grid-connected points can use cellular networks. If the project requires high continuous online availability, a primary wired link, 4G backup link and dual SIM redundancy can be planned to prevent the entire site from being offline for a long time after a single communication link fails. The G809s supports dual SIM cards, and provides Gigabit electrical ports, SFP optical ports and cellular network access capabilities.

1.3 Remote Maintenance and Data Transmission Security

Many grid-connected cabinets are delivered hundreds of kilometers away from the manufacturer. When problems occur with PLC parameters or communication device configurations, sending engineers to the site every time will lead to extremely high after-sales costs. The G809s supports cross-site networking, and is compatible with multiple VPN modes including PPTP, L2TP, IPSec, OpenVPN, GRE, VXLAN and WireGuard, which can establish a remote access channel according to the project's network architecture.

It should be noted here that the industrial 4G router is mainly responsible for network connection. If protocols such as IEC 101/104, IEC 61850 and Modbus on site need unified conversion, a communication management machine or edge gateway should still be configured according to the project architecture. The router cannot be simply regarded as a conversion device for all power protocols.

2. On-Site Deployment Procedures

The most common link is:
Electricity Meter / Protection Device / PLC → Communication Management Machine or Industrial Switch → G809s → Optical Fiber / 4G → Power Monitoring Platform

In the early design phase, first sort out the interfaces, IP addresses, network segments of the devices inside the cabinet, and confirm the final platform to which the data will be uploaded. Devices with network ports are directly connected to the LAN side; for RS485 devices collected uniformly by the communication management machine, the data will first enter the communication management machine and then be uploaded via Ethernet.

Then configure the LAN, WAN, cellular network and VPN parameters of the router. For projects with optical fiber conditions, the wired link can be used as the priority, with 4G as the backup; for small grid-connected points without fixed networks, the platform can be directly connected through the cellular network.

In terms of installation, the G809s supports DIN rail mounting, with a power supply range of DC 9~60V, an operating temperature range of -40℃~75℃, and adopts industrial-grade EMC design, which is very suitable for installation inside control cabinets such as grid-connected cabinets and box-type substations.

Finally, conduct joint debugging. In addition to confirming that real-time power, voltage, current, switch on/off status and alarms can be uploaded normally, you should also actively disconnect the main network and power on the device again to test whether the backup link switching, device reconnection and VPN recovery work properly.

3. Key Details to Note Before Batch Deployment
3.1 Do Not Place the Antenna Deep Inside the Metal Cabinet

The metal shell of the grid-connected cabinet will significantly attenuate cellular signals. It is recommended to test the signal in the actual state after the cabinet door is closed, and consider leading the antenna out of the cabinet in weak signal areas.

3.2 Distinguish Between Network Services and Control Services

Monitoring data, video data and protection control do not belong to the same security level. Services involving relay protection and fast control cannot simply rely on public 4G networks, and dedicated links should be designed in accordance with the communication and security requirements of the power project itself.

3.3 Complete Grounding and Line Isolation

Communication cables and power cables should avoid long-distance parallel laying with high-voltage power lines, and the grounding terminal of the router must be reliably grounded. The industrial 4G router G809s is equipped with a grounding terminal, reverse polarity protection and a built-in watchdog, supporting device self-inspection and fault self-recovery.

3.4 Do Not Launch Batch Deployment Directly

First select several representative sites for continuous operation, covering scenarios such as strong electromagnetic interference, weak signals, main link disconnection and device restart. Then determine the acceptance indicators such as disconnection recovery time and data integrity according to project requirements.

For grid-connected cabinet manufacturers, the industrial 4G router truly solves the "last mile" problem after delivery. The devices inside the cabinet may already be very mature, but if the site network is unstable, background monitoring still cannot be implemented. Taking the G809s as the communication exit of the grid-connected cabinet, and uniformly planning wired, optical fiber, 4G and remote maintenance, there is no need to make large-scale modifications to the original control logic. This will make scattered grid-connected devices easier to access the centralized monitoring system, and greatly reduce the workload of frequent on-site network troubleshooting in the later stage.