-
Scam Alert. Members are reminded to NOT send money to buy anything. Don't buy things remote and have it shipped - go get it yourself, pay in person, and take your equipment with you. Scammers have burned people on this forum. Urgency, secrecy, excuses, selling for friend, newish members, FUD, are RED FLAGS. A video conference call is not adequate assurance. Face to face interactions are required. Please report suspicions to the forum admins. Stay Safe - anyone can get scammed.
Suggestions on my vfd conversion
- Thread starter DPittman
- Start date
I wonder if he defeated the twisted pair benefit by using wires randomly?
Here is what I would try. Connect the tach to the sensor and the separate power supply and don't have the wiring from the sensor or power to the display anywhere near the wiring for the pot and see if it works with the VFD running. If it does, then there is electrical interference between wires.
I can believe the EMI. I have a TV in the shop that gets fed via coax which I drive with a RF converter. Your choices in the shop are to mull-sand, or watch TV, but not both. The VFD screws up the TV feed something fierce. (Note: I have the TV on for ambient noise most of the time, no safety warning needed 
)
)
DPittman
Ultra Member
I initially did have separate wires but they were run along side others.
No the cat cable isn't shielded
I thought I saw a post that showed you had more than one of these vfd's? maybe I am wrong, but if you did and you haven't had enough fun yet you could swap out the vfd.
DPittman
Ultra Member
Yes I have another duplicate vfd mounted in the same closure. It is for a drill press that will be wired the same way. I'm waiting for a motor for that one so we will see if it behaves any differently
DPittman
Ultra Member
Oh I'm learning!
I just read that twisted pair wiring is done to reduce interference. Ah ha! My potentiometer needed 3 wires from the vfd and my tach needed 2, so I just used wires as needed ie not matched pairs. I haven't tried rewiring it yet but I have a stinking suspicion that might be my tach problem. It definitely is some sort of interference problem.
I just read that twisted pair wiring is done to reduce interference. Ah ha! My potentiometer needed 3 wires from the vfd and my tach needed 2, so I just used wires as needed ie not matched pairs. I haven't tried rewiring it yet but I have a stinking suspicion that might be my tach problem. It definitely is some sort of interference problem.
And powered from the VFD? Everything is working as you want now?
Last edited:
DPittman
Ultra Member
Oh actually I haven't tried that (embarrassed) but it works now with external power AND the potentiometer so I am assuming all is well but I guess I will never learn about making assumptions. I will report back once I get it rewired to try that.
And the fan......
DPittman
Ultra Member
And finally the completed post.
While using twisted pair wiring correctly did improve the performance of the tach however it still would not work when powered with the vfd. I even tried shielded cable. And I tried a ferrite collar ( not that I know a damn thing about using those), the power from the vfd just was not compatible with the tach.
I ended up making a separate powered switch box just for the tachs.
My wiring is looking a bit like Helen Kellers knitting but with two vfds and external controls there gets to be quite a bit of wiring.
I probably spent as much time on making the control boxes as I did wiring the rest and now once I have it figured it wouldn't be much to do another all over again.
I prefer my new control switches for the mill on the front as opposed to the originals that were back on the side of the machine.
A few pics and a video.
While using twisted pair wiring correctly did improve the performance of the tach however it still would not work when powered with the vfd. I even tried shielded cable. And I tried a ferrite collar ( not that I know a damn thing about using those), the power from the vfd just was not compatible with the tach.
I ended up making a separate powered switch box just for the tachs.
My wiring is looking a bit like Helen Kellers knitting but with two vfds and external controls there gets to be quite a bit of wiring.
I probably spent as much time on making the control boxes as I did wiring the rest and now once I have it figured it wouldn't be much to do another all over again.
I prefer my new control switches for the mill on the front as opposed to the originals that were back on the side of the machine.
A few pics and a video.
DPittman
Ultra Member
Yes the tach wiring issues almost got the best of me but I'm glad I persevered. I used 20 guage sheet metal for my boxes. Yes I made the vfd cabinet as well but the side the door is hinged on could have been made a bit more ridged. I used only one center hinge because that's all I had but two would have been much better. The fan in the top of the box runs whenever the vfds are powered and the fans on the vfds themselves only come on when the vfd is actually running the motors. I powered the extra fan of the vfd ports.@DPittman looks great! Glad you got the tach to workout. Did you make the VFD cabinet as well? Great job on the boxes, what thickness sheet metal did you use?
At first I thought you had a mask on in the video, then I realized it was just your phone.