Thread: Huanyang 24v line and tachometer

What's the current draw of the tacho?

Originally Posted by TheNutter

Hi All

I have been gathering things to convert my lathe to VFD variable speed and yesterday got the whole thing working on the bench. One of the things that I have acquired is a 'Hall Effect' tachometer off ebay. This needs a line voltage up to 24v to run. Yesterday I powered it up off the unused 24v terminal on my Huanyang 1.5kw VFD. This seems OK but I wonder if it is going to cause any problems? Has anyone tried driving accessories from this line? Any comments welcome!Regards

Ian

I think the Huangyang 24VDC output is rated for 0.1A only. If your tacho draws less than that, and no other 24V loads are attached, you could be fine.

I did not know their VFD's were accepting tachometer inputs for closed loop vector speed control though? Are you sure the tacho input is suitable for variable speed regulation feedback, and not only for much slower PID control purposes? If so, that would instantly make Huangyang VFD's a higly desirable choice for machine tools. I know of no other VFD brand that would offer closed loop vector speed control below $1k.

Thanks for the quick responses gents!

Bob - I don't know, google hasn't been my friend. I can find that just the the display is rated at 23 mA. I will have a go at measuring it.

CBA - I suspect that closed loop vector speed control is probably beyond the Huangyang, it is certainly beyond me. Getting the potentiometer working was the limit of my skills! I am just aiming for a simple display tachometer. The manual shows the UPF terminal as being limited to 100 mA but there is nothing that I can see for the terminal that is marked 24v.

Cheers

Ian

Originally Posted by TheNutter

...

CBA - I suspect that closed loop vector speed control is probably beyond the Huangyang, it is certainly beyond me. Getting the potentiometer working was the limit of my skills! I am just aiming for a simple display tachometer. The manual shows the UPF terminal as being limited to 100 mA but there is nothing that I can see for the terminal that is marked 24v.

Cheers

Ian

Ian, maybe the hall sensor is for an RPM meter then?

Anyway, it is not recommended to use an internal VFD power supply for anything not directly related to the VFD operation itself. The reasons are twofold. Once it is because the VFD generates considerable RF noise - that would be directly conducted through the 12 or 24VDC power lines to other equipment that may not tolerate such levels of RF noise. The other reason is these 12V and 24V supply voltages are very low current - typically only 100mA each, just enough to drive the VFD's inputs and outputs - and it is not 100% sure what happens if you overload these. They should be overload proof.... but is it worth finding out the hard way? I recommend you use a separate external power supply. Maybe a wall wart if it was only for an RPM meter?

Thanks CBA, that is the sort of thing that I needed to know and I will take your advice. It is just for an RPM meter, I was just trying to avoid the proliferation of stuff...

I can feel a fully blown switchboard coming on for this lathe.

Regards

Ian

Just to confirm, are you talking about a Hall Effect sensor connected to a seperate Tacho display which needs 24v to operate?

I have these except that mine runs on 12v which is simple because I have a 12v supply already to run the LED light. I have had them for ages and just happened to get them out a couple of days ago with a view to install them. I am going to do a shuffle around with the lathe wiring and switches and thought I would include the tacho install.

Dean

Yes Dean, it's one of the cheap ones off eBay. Mine is rated to run anywhere between 8 - 24v. It worked well when I had a play with it on the bench. I think that the idea of powering it off the line for the LED light is a good one. I am trying to avoid having separate power supplies for everything on this lathe.

Regards

Ian

Originally Posted by TheNutter

Yes Dean, it's one of the cheap ones off eBay. Mine is rated to run anywhere between 8 - 24v. It worked well when I had a play with it on the bench. I think that the idea of powering it off the line for the LED light is a good one. I am trying to avoid having separate power supplies for everything on this lathe.

As CBA says it's pretty simple to take the 240V of the line to the VFD and run it to a wall wart to generate 12V..

Here is how I did it on my Hercus to generate 12V for the computer fan to vent the VFD enclosure..
https://www.woodworkforums.com/showth...87#post1320687

A "wall wart". That is a new one.

That is what I have except that I pulled it apart and soldered wires on in place of the pins. This just sits in my lathe electrical cabinet and is wired to the 240v input via a switch. I may need to change that if I want the tacho to work when the light is turned off although that situation is unlikely. Maybe I don't even need a switch.

Dean

Dean - I am not going to switch the tacho. Its going in a prominent position and I want it to act as an indicator that the machine is powered up.

Bob - I am heading towards something similar but I want to mount it on the machine, its not impossible that the whole thing may yet move. I had no boxes that were the right size but one of Bunnings $20 toolboxes is just about smack on what is recommended in the manual. With a box of the recommended size I am not sure if I need to make provision for ventilation?

Regards

Ian

Originally Posted by TheNutter

Dean - I am not going to switch the tacho. Its going in a prominent position and I want it to act as an indicator that the machine is powered up.

Bob - I am heading towards something similar but I want to mount it on the machine, its not impossible that the whole thing may yet move. I had no boxes that were the right size but one of Bunnings $20 toolboxes is just about smack on what is recommended in the manual. With a box of the recommended size I am not sure if I need to make provision for ventilation?

Regards

Ian

I described it badly. The switch is for the LED machine light, but will also switch the Tacho as it is at the moment with the "wart" input switched. I don't want the Tacho switched. I probably don't need the light switched either. I am just going to remove the switch so both come on with the main power switch.

I like the toolbox idea. If I remember next time I am near Bunnings I will get one or two, but that may be some time away.

Dean

Originally Posted by TheNutter

Dean - I am not going to switch the tacho. Its going in a prominent position and I want it to act as an indicator that the machine is powered up.

Bob - I am heading towards something similar but I want to mount it on the machine, its not impossible that the whole thing may yet move. I had no boxes that were the right size but one of Bunnings $20 toolboxes is just about smack on what is recommended in the manual. With a box of the recommended size I am not sure if I need to make provision for ventilation?

You mean this tool box? more details here https://www.woodworkforums.com/showth...68#post1879068
This is more of a transport box and I will normally be operating it with the door open


I f you are going to close the door I would at least add a bunch of ventilation holes at the top and bottom of the box.
Also I would earth the box itself.

Yes Bob, that is the one.

Regards

Ian

I have now installed the Bunnings tool box as a switchboard to hold the VFD on my lathe. Its so thin that as a tool box it makes a good switchboard!

IMG_0331.jpg

I have put in top and bottom vents. The top one which is on the LH side is exactly the size of a 3" computer fan should I need to fit one. That is a 12v wall wart on the bottom LH side to run the tacho and the LED machine light.


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I backed the lid with a piece of perspex, this will enable me to see the VFD display and has stiffened the lid so that it doesn't rattle. I will keep the door closed with a couple of screws.

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The switching is back in the original location. The sensor for the tacho is mounted in the back of the original switchboard casting which means that the wire can be kept very short.

IMG_0334.jpg

This is the whole thing as it presently stands.

I have the VFD set to run from 30 - 90 Hz to try and avoid the low torque bands and over stressing the motor. This means that in the original low 3 belt position I have what was the original middle 4 of 6 speeds of the lathe achievable via the pot. I look forward to a life with a lot less belt changing! The lowest belt speed, in backgear at 30 Hz gives a bottom speed of 40 rpm for threading.

The whole thing is a lot smoother that the original rather clapped out motor that I have replaced.

The only thing that I don't like thus far is with the 30 - 90 Hz setting a lot of the range of the pot isn't used. Has anyone experimented with another pot to overcome this?

Regards

Ian

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