What are the functions of the cables used in the design of servo level gauges?
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This post was last edited by Zhang Naai Yang Jingwang on 2017-3-21 at 17:01. As shown in the photo, it has been installed on site, but I’m not sure how to handle the cables; is there anyone who knows how to do this? There are two more junction boxes that haven’t been photographed. Tag numbers LT21101 and 21102
The tag numbers are LT21101 and 21102
Great picture posted by the original poster – it cured my cervical spondylosis that had plagued me for years; P;P
This post was last edited by budaoweng123 on 2017-3-21 at 17:19. Ordinary servos are four-wire instruments that require a separate power supply. Two additional output paths: one leads to the control room, and the other leads to the on-site indicator at the tank floor.
The signals are all connected to one box, and then transmitted to the control room via 232 or 485 communication
It’s too blurry! The photo is bad If that’s correct, it should be: power supply, signal, RS485 communication line
Those two servo level gauges communicate with the DCS via a communication method, usually serial communication over 485. I didn’t see the power cable for the servo level gauge; is it in the electrical section?
I took a quick look at the wiring diagrams for LT21101 and 21102: Both LT21101 and LT21102 are powered by 220VAC. They have serial communication, likely in RS485 mode. When the liquid level is too low, signals are sent to the DCS, while when the liquid level is too high, signals are sent to the SIS (LT21103). There are some points that are not clear from the diagrams; it seems there is an issue with the arrangement of the signal terminals in the on-site cabinet room. The signals from TB1 and TB7 appear to be in a ‘messy’ state. According to the design, low-level signals should all be fed into the terminals on the DCS side, while high-level signals should all be fed into the terminals on the SIS side, right?
No, most of them are still 4–20 ma