Bunt23
Member
Hello all,
I have a mixing machine that measures a specific amount of water, adds it to a mixing chamber and creates a homogenous slurry. The way we measure the amount of water going into the mix chamber is with a paddlewheel water meter. Omega FP-5063 is the specific part number. It has a paddlewheel with a metallic piece embedded in it that makes a prox switch each time it rotates. The number of rotations are sensed using a high speed counter input on a PLC. I’ve been asked to automate a few steps in our process, and to do so I’ve added 2 solenoid air valves and 1 water valve (essentially, the machine now has 4 more outputs [1 of the air valves is double acting]). Since I’ve made those modifications, our paddlewheel water meter failed. Thinking it was a coincidence, I replaced it with a new one, and that one failed shortly thereafter (completed 2 machine cycles prior to crapping out). Thinking maybe THAT was a coincidence I found one more, hooked it up to a bench top power supply, and manually spun the paddlewheel by blowing air into the meter while measuring voltage on the meters signal wire. It worked exactly as it should, so I put that one on the machine. Once again, I got through 3 or 4 cycles and the water meter quit working. I removed it and went back to the bench top. I hooked it back up to a power supply and blew air in it to manually spin the paddlewheel to see if it would output a signal. Nothing. Also did that with the other 2 that had failed. No signals from either of them as well. So they definitely failed somehow. I then proceeded to check all my connections in the electrical cabinet related to the water meter, and everything is wired per the manufacturer specs. I measured the voltage it sees, and it is 24VDC, per the manufacturer spec. I have this same water meter on 18 other machines that are wired the same way that work with no problems. The only difference between the problem-child machine and the rest is that I wired in a few more valves that the PLC turns on and off during the process. Other than that, the machines are identical. I decided to remove the valves I added to return the machine to its original state. Then, I put a new water meter in and ran some cycles. I think I’ve run over 40 cycles now and have had no issues. How can wiring in a few extra solenoid valves to some outputs on the PLC cause a paddlewheel prox sensor to fail? It just doesn’t make any sense to me. Can anyone shed some light on what may be happening?
I have a mixing machine that measures a specific amount of water, adds it to a mixing chamber and creates a homogenous slurry. The way we measure the amount of water going into the mix chamber is with a paddlewheel water meter. Omega FP-5063 is the specific part number. It has a paddlewheel with a metallic piece embedded in it that makes a prox switch each time it rotates. The number of rotations are sensed using a high speed counter input on a PLC. I’ve been asked to automate a few steps in our process, and to do so I’ve added 2 solenoid air valves and 1 water valve (essentially, the machine now has 4 more outputs [1 of the air valves is double acting]). Since I’ve made those modifications, our paddlewheel water meter failed. Thinking it was a coincidence, I replaced it with a new one, and that one failed shortly thereafter (completed 2 machine cycles prior to crapping out). Thinking maybe THAT was a coincidence I found one more, hooked it up to a bench top power supply, and manually spun the paddlewheel by blowing air into the meter while measuring voltage on the meters signal wire. It worked exactly as it should, so I put that one on the machine. Once again, I got through 3 or 4 cycles and the water meter quit working. I removed it and went back to the bench top. I hooked it back up to a power supply and blew air in it to manually spin the paddlewheel to see if it would output a signal. Nothing. Also did that with the other 2 that had failed. No signals from either of them as well. So they definitely failed somehow. I then proceeded to check all my connections in the electrical cabinet related to the water meter, and everything is wired per the manufacturer specs. I measured the voltage it sees, and it is 24VDC, per the manufacturer spec. I have this same water meter on 18 other machines that are wired the same way that work with no problems. The only difference between the problem-child machine and the rest is that I wired in a few more valves that the PLC turns on and off during the process. Other than that, the machines are identical. I decided to remove the valves I added to return the machine to its original state. Then, I put a new water meter in and ran some cycles. I think I’ve run over 40 cycles now and have had no issues. How can wiring in a few extra solenoid valves to some outputs on the PLC cause a paddlewheel prox sensor to fail? It just doesn’t make any sense to me. Can anyone shed some light on what may be happening?
