3 phase motor connection plate

Update on my motor quandary,

I bought one of those cheap VFD's off Amazon on Friday it was delivered Saturday, so I went and connected it up, and it works !!! . The motor is whisper quiet, the two speed changes are fully functional (although I do let it stop rotating before I switch it across) I don't suppose I'll really use it as obviously I now have variable speed via the VFD. Ii appears to have plenty of torque as I popped a 50mm shell mill in and faced off some steel resulting in a very nice finish I haven't yet done any drilling which I assume will require more torque but I'm confident all will be good. I am extremely happy and quietly relieved. I have now ordered another for the motor that drives the table traverse, having tried the VFD on that first to make sure it is compatible.

Congratulations! Is it a 380V VFD?

Important not to switch speed whilst the power is on because that's the greatest weakness of a VFD. As it's the sort of thing I do in moments of carelessness, might be worth fitting some form of physical measure to stop it, such as taking the handle off the switch! Or tying a huge red ribbon round it!

Dave

Hi Dave yes it is a 380v VFD, I think removing the handle is a great idea so much so after reading your post I popped out to the workshop and did just that.

Cheers John

Don't forget that the restriction on load switching applies to the traverse as well. If it is electrically controlled you will have to connected the mortor directly to the VFC and then connect the control switches to the control inputs of the VFD and set it up accordingly.

Robert G8RPI.

Good point, I had not actually thought of that, however I did use the original switch connected to the control inputs of the VFD but to be honest that was so I could keep the original switch gear on the machine. My next challenge is to work out how to incorporate the existing limit switches on the table into the electrical system.

There is always the other option of having 3 phase connected to your house.

That is the route I took.

I still use variable drives on some of my machines but only for speed control.

Les

An effective way to avoid inadvertent speed switching whilst the VFD is running would be to use one of the mechanically interlocked contactor units used in forward - stop- reverse systems. With these the "on" contactor moves a mechanism preventing the other contactor from turning on. Need to use the stop button first to relase the latch before the other speed can be selected.

The one I got for when I finally finish sorting my American style vertical opening bi-fojd garage door was about £40, I think.

Clive

When I upgraded my lathe to use a VFD I opened the CTL box to figure out the way to incorporate the VFD. I was faced with the maze of wires, switches and relays shown in the photo below. After a lot of head-scratching I realized that it was really all about controlling the forward/reverse power to the motor by means of the low voltage switches. The relay KM1 provided the mains power and all the motor switching was via the other relays.

The Original Layout diagram shows the salient features of the original CTL wiring and the Modified for VFD shows the far simpler layout when the VFD handles everything. All the original external controls of the lathe work as they did before the VFD, but I added a little speed control rheostat on the lathe control panel.

That looks a little bit like the inside of my cabinet lol, I am not that confident when messing with electrics so I think I will be rewiring my machine from scratch and probably removing all the original electrical equipment and wiring apart from the switches.