Process Area Activity – [I See Now-12]: The Power Supply Was Really Connected Reversely
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This post was last edited by *nht1 on 2016-10-24 21:22. First of all, it’s a joke, and they don’t want to talk much about it afterwards. It happened in Shanghai the year before last; the personnel in charge of mechanical and electrical equipment reported that a deep-well submersible pump had insufficient flow rate. After inspection, it was determined that the pump needed to be replaced. I went to the site and saw that the flow rate indeed was low, so I agreed to the replacement. After the start-up was completed in the afternoon, the personnel from the mechanical, electrical, and instrumentation department came back and said that the flow rate was still low. I went to the site to observe again, and it was indeed the same as before. Just ask the electrician: Is the power cable connected incorrectly, reversed? At this point, the mechanic, electrician, and instrument technician all agreed that it was correct – connecting it in reverse would prevent water from flowing. The electrician also said: Having worked in this field for so many years, something like connecting the wires incorrectly simply doesn’t happen. There’s really no other option but to restart; yet the data usage remains unchanged. I said, “Let’s give it a try – change the wiring and see what happens.” An electrician said it would do no good to try, but he still went ahead and made the change. As soon as it was turned on, the traffic volume increased immediately, several times higher than before, and everyone said: 【The power supply is really connected reversely.】 Usually, if the pump’s power cable is connected reversely, no fluid will be discharged. However, some pumps still manage to discharge fluid even when connected reversely, though at a lower flow rate. This is related to the impeller shape and the position of the liquid outlet, as well as to ensuring that the pump does not get damaged.
I’ve encountered a similar situation; the power cable of the exhaust fan was connected incorrectly, which caused me a lot of trouble
There are indeed quite a few faults caused by reversed wiring...
I’ve encountered this too: the submersible pump was dropped into the sea, the resistance test failed, so it was pulled out and its electrical insulation was rechecked. When lowering it back down, it was found that one pump had high water pressure while the other didn’t; so it had to be lifted out again, and it was confirmed that the power connection was reversed, causing the pump to operate in reverse.
Just by looking at the title, I thought it might be that case; once I checked, it was indeed the same. I’ve encountered this situation once as well
Generally, a submersible pump will still discharge water even if the power phase sequence is incorrect; I have encountered such a situation before. After the construction team installed the wiring and conducted tests, water was produced, but the flow rate was very low. At that time, the construction team thought that the equipment chosen was not powerful enough, and they believed that there would be no problems with installation. Later, after I went to the site and had them change the wiring order, everything worked properly, and they were quite convinced by that. Since submersible pumps are underwater, they are difficult to observe; it is generally assumed that as long as water comes out of them, everything is normal. Actually, the wires are connected in reverse, and this is evident both in the vibration and in the water output.
:）. I just chuckled; I’ve encountered situations where the wires were connected in reverse, and I’ve also seen cases where the check valves were installed backwards. During installation, care was not taken as to the orientation of the valves; there were also cases where it was insisted that the valves had no distinction between front and back, and orifice plates likewise had no such distinction. I’m laughing in anger.