Suggestions on my vfd conversion

[RobinHood]

Any one use (or wish they had) shielded cable in their vfd conversions?

In you post #83 above you are wondering about shielded cable. So when I saw you using speaker wire, I thought you were having / or suspecting of having interference issues.

I am sure someone will chime in and educate us about this, but personally I would not use speaker wire in a control circuit.

In my VFD setup for the mill I used 4x2 twisted pair telephone wire. I know our phone line is ~50V DC on the active pair and you can run multiple pairs in the same jacket without interference, so I figured that it could easily handle 12VDC. I do use the original FWD/REV (High/Low) switch on the mill whose contacts are good for 440VAC at the FLA of the motor. Never had any problems.

 

[DPittman]

In you post #83 above you are wondering about shielded cable. So when I saw you using speaker wire, I thought you were having / or suspecting of having interference issues.

I am sure someone will chime in and educate us about this, but personally I would not use speaker wire in a control circuit.

In my VFD setup for the mill I used 4x2 twisted pair telephone wire. I know our phone line is ~50V DC on the active pair and you can run multiple pairs in the same jacket without interference, so I figured that it could easily handle 12VDC. I do use the original FWD/REV (High/Low) switch on the mill whose contacts are good for 440VAC at the FLA of the motor. Never had any problems.

Yes I had ran across some youtube and postings talking about using shielded cable for the power to and from vfds to avoid electrical magnetic interference. I hadn't heard anyone else talk about that so I asked. When I went to buy wire today I looked for some but saw none and came home with other cabling (more on that later).

I have quite a mix of wiring coming from my external controls, mostly because I used what I had. I used the speaker wire in places because i figured it was plenty heavy enough (18 gauge) and it's easy to work with. Why would you avoid it, is it known to cause I EM interference problems? I did not consider any interference when I chose my wire.

 

[YYCHM]

I wouldn't worry about it unless it's a long run mixed in with AC or Comms cables. I used some trailer lighting wire I had. My FWD/REV switch is no more that a foot from the VFD. You can't go crazy with the gauge due to those low voltage connection terminals being so small.

I'm really curious to see how this separate FWD/REV switch thing works out. What do you anticipate if you have them both selected?

 

[YotaBota]

Telephone wire is okay but Cat5 computer cable is better for the control lines. It protects the signals to the computers so it is more than enough for the VFD. Plus there are eight wires in one cable, you can use however many you need for the switches and the pot.
I used the original drum switch for fwd/stop/rev and a 1k pot for frequency control, all on the Cat5 cable. I had a piece of shielded cat five in the cable pile so I used it for my control lines.
What tach are you using?

 

[DPittman]

Telephone wire is okay but Cat5 computer cable is better for the control lines. It protects the signals to the computers so it is more than enough for the VFD. Plus there are eight wires in one cable, you can use however many you need for the switches and the pot.
I used the original drum switch for fwd/stop/rev and a 1k pot for frequency control, all on the Cat5 cable. I had a piece of shielded cat five in the cable pile so I used it for my control lines.
What tach are you using?

Hall effect sensor available on Amazon. Sorry I can't figure out how to post an Amazon link from my phone. Same gizmo @John Conroy used in his drill vfd conversion.

 

[DPittman]

I wouldn't worry about it unless it's a long run mixed in with AC or Comms cables. I used some trailer lighting wire I had. You can't go crazy with the gauge due to those low voltage connection terminals being so small.

I'm really curious to see how this separate FWD/REV switch thing works out. What do you anticipate if you have them both selected?

Hmmn I'm not sure i have it figured out yet. I thought @John Conroy had a similar setup working.

 

[YotaBota]

I'm using the same tach as well and I followed John's lead using a 220volt wallwart for power.
I have the TECO VFD and they recommended not to use the vfd's 10volt for the tach power.

 

[DPittman]

I'm using the same tach as well and I followed John's lead using a 220volt wallwart for power.
I have the TECO VFD and they recommended not to use the vfd's 10volt for the tach power.

I thought using the vfd power port would be ideal for this and my cooling fan.

 

[John Conroy]

I used cat5 cables for all my control circuits on my lathe. Electric motors and VFD outputs are an electrically noisy environment and the low voltage controls are very susceptible to EMI so twisted pair wiring or a shielded cable like cat5 is recommended to prevent control anomalies. If you are using the factory control button pad and a ribbon cable to remotely mount it that should be fine, it's working well on my drill press.

As Mike suggested you do need a seperate 12 volt power source for the digital tachometer.


A very simplified explanation of how the control circuits work is this. The control circuits use a reference voltage usually 5, 8, 10 or 12 . Each control circuit has a voltage dropping resistor and a voltage monitor connected to it. The DCM or digital common is a low reference or ground. When you connect a switch between a control circuit and the DCM ground the voltage monitor will measure high (reference) voltage when the switch is open and low (zero) voltage when the switch is closed. When a switch is open there is no current flow and therefore no voltage drop across the resistor so the voltage monitor measures high. When the switch is closed all the reference voltage is dropped across the resistor so the voltage monitor measures low. For example if you program your VFD so switch 1 is for forward rotation, when the voltage monitor for that switch will make that happen when it sees the voltage go low on that switch circuit. When 2 conflicting switch circuits are closed at the same time a trouble code will set. This type of circuit is very common in any electronic device that uses a low current switch to control an output.

PS--picture now edited due to brain fart.

 

[RobinHood]

@DPittman , I have a lifetime supply of CAT5e cable - PM sent

 

[John Conroy]

I thought using the vfd power port would be ideal for this and my cooling fan.

That circuit can't supply enough current for both. It might work for the tach but probably not the fan. To avoid problems just use a remote 12V power supply.

 

[DPittman]

That circuit can't supply enough current for both. It might work for the tach but probably not the fan. To avoid problems just use a remote 12V power supply.

The fan only takes .15 amps and the tach is only 30 milli-amps.
What do they put that power terminal there for?

 

[DPittman]

So I thought I was keeping things simple here,

but not simple enough for me I guess. Here is my external control panel that I'm trying to hook up

 

[YYCHM]

This thread inspired me to wire out the Emergency Stop (ES) input on my mill VFD to see how it behaves.

I'm not liking what I'm seeing. It stops when you trigger the ES but carries on where it left off when you remove the ES input. The display does not indicate anything unusual. I would prefer if it stayed in an ES state until both the ES and FWD/REV signal were removed. @kevin.decelles or anyone else for that matter how does your ES behave?

Craig

 

[DPittman]

This thread inspired me to wire out the Emergency Stop (ES) input on my mill VFD to see how it behaves.

I'm not liking what I'm seeing. It stops when you trigger the ES but carries on where it left off when you remove the ES input. The display does not indicate anything unusual. I would prefer if it stayed in an ES state until both the ES and FWD/REV signal were removed. @kevin.decelles or anyone else for that matter how does your ES behave?

Craig

Well I'm sure you will be more successful at your endeavors than I have been at mine so far. Good luck, I wish I could offer advice but you know what that would be worth if I did. Hee hee.

Please excuse the poor video and the bumbling narrator, but have a look at this video of my issue please.

 

[RobinHood]

Try connecting the second lead of the RPM meter straight to the bare copper grounding wire to see what happens. Maybe that COM port is not a “true” ground when you have the external inputs enabled.

 

[Brent H]

@DPittman : are you getting an RPM readout on the VFD? I wonder if you have something negating the feed signal to your readout. As far as I know with the VFD the rheostat would just control the VFD and your rpm feed back should be a completely separate connection.

 

[kevin.decelles]

My ES switch stops the motor and when u release the motor starts again.

While it is stopped my display shows this

But if u turn the switch to stop WHILE it is in es, it will stop

Basically, it will return the machine back to the state represented by the switches


Sent from my iPhone using Tapatalk

 

[DPittman]

Try connecting the second lead of the RPM meter straight to the bare copper grounding wire to see what happens. Maybe that COM port is not a “true” ground when you have the external inputs enabled.

Yup I tried that actually and I got nothing whatsoever on the readout. And I tried the other COM port too. I'm baffled.
Those two far left and right terminals seem to power the external fan I have just fine. ?

 

[DPittman]

@DPittman : are you getting an RPM readout on the VFD? I wonder if you have something negating the feed signal to your readout. As far as I know with the VFD the rheostat would just control the VFD and your rpm feed back should be a completely separate connection.

I believe I have to somehow program the vfd to read rpm on the panel. It shows amps and frequency.