In the review of communication faults in 110kV and above substations, a large proportion of port burnouts are caused by lightning strikes, ground faults or switching operations. Optical isolation is often mentioned in the transformation plan before networking. The physical reasons behind this statement are worth clarifying.
Ground potential differences drive current into signal lines
When a single-phase grounding or lightning current discharge occurs in a substation, the ground grid potential at different points in the substation can increase by hundreds of volts in an instant. Both ends of the cable between the relay room and the outdoor terminal box are grounded nearby. This potential difference is directly added to the shielding layer and signal line of the RS485, 232 or audio line, and the driving current invades the equipment port along the copper cable. The optical fiber is composed of a quartz core and a non-metallic sheath. It does not form a conductive loop and theoretically cuts off this entrance.
Optical isolation does not mean tearing everything down and starting over
A common practice is to retain the original device and replace only the easily affected communication segments with optical fibers: transceivers or optical transceivers are used on the outdoor side to complete photoelectric conversion, and the indoor side is concentrated on the distribution frame. Can refer toOptical isolation renovation of a 220kV substation communication networkWith the channel-by-channel photonics approach, the equipment on both sides is grounded nearby, and the copper cable no longer bridges the two grounding systems. The overall channel division method can be combined withCommunication transformation plan for electric power and new energy stationsCome sort it out.
Which channels should be prioritized for actinization
- Remote control, temperature and humidity, and access control RS485 channels connecting the outdoor terminal box and the protection cubicle;
- Dispatch traffic and administrative telephone lines laid across different grounding networks;
- Industrial video and Ethernet links run parallel to power cables over long distances along cable trenches.
To determine the priority, you can draw a ground network demarcation map: any channel where the same copper cable is installed between two ground systems is a photochemical candidate. After the transformation, the insulation conductors and markings of the optical cables entering the station must be reviewed. If you need help sorting out the channel list, you can contact EB-LINK technical support.