Tunnel ventilation and power supply are the key to operational safety: the jet fan automatically starts and stops based on CO and visibility, and the distribution box outside the tunnel must report switch status, voltage and current. The signal speed is not high but very scattered. It is much more troublesome to use a data optical terminal to concentrate the light than to pull a bunch of cables.

First divide the signals into three categories and then assign ports

• Control instructions: fan start and stop, wind direction switching, mostly switching values or Modbus write operations, requiring clear direction and timely response.
• Status feedback: fan operation/fault contacts, circuit breaker opening and closing positions, collected using remote signaling and then sent back through the data channel.
• Analog quantities: CO/VI concentration, distribution box voltage and current, are generally converted into 485 messages by the acquisition module and then polished.

Choose the model based on points and distance

When single-hole fans and distribution points are concentrated in one or two on-site boxes,Three-in-one data optical transceiverMultiple channels of data and switching values can be combined into one fiber core, and the occupation of cabinet ports is significantly reduced; when there are only a few 485 return points, use2-way bidirectional RS485 data optical terminalPoint-to-point connection is more direct. The distance from the substation outside the cave to the monitoring room is often several kilometers. Select a single-mode model and leave sufficient optical power margin according to the distance.

Isolation and power supply

Fan contactor action and lightning strikes will induce spikes on the 485 line. Select a data optical terminal with electrical isolation to block crosstalk and ground single-end to avoid loops. The on-site box usually draws centralized power supply from DC24V or -48V communication power supply, which is more controllable than drawing power nearby in the cave. EB-LINK This kind of electromechanical signal glazing can be referred toCommunication transformation plan for electric power and new energy stationsIf you need to check the isolation and grounding practices, please dial 0755-83179002 to check the location and distance.