PM1440-2SM VFD conversion

[B2]

Hi Mike,
Understood.
I had a similar problem with insufficient DIN rail space. I added a short section next to the VFD. You can see it in the photos. What I was trying to say is that perhaps you want to put a volt meter in the same housing as the RPM meter is in. You will have already run the 12V there, but you will need a wire to your pot, where ever that is located and you will need to be aware of the ground lines making unnecessary runs or loops to avoid noise. By the way the digital displays do make some switching noise as the segments change. The more active segments the more current the display requires. If your 12 volt supply is some distance from the displays you may want to add some capacitance at the power connections at the displays. I did not have to add capacitance, but the need for controlling noise is dependent upon the arrangement of things.

Anyway, I like having the ability to see what frequency the VFD is going to be running at before turning on the motor.

I am looking forward to seeing your final circuit and physical layout. So do post them.

Dave

PS. Unless you are just into building and modifying the lathe and its features, once you get the lathe up, it is working ok and you are making things you probably will never go back and make changes. You know the old saying "If it isn't broken don't fix it." That is probably why, even though I have designed and built a pcb to replace my hand wired board, I have yet to replace it. Also, as I have found not all lathe's have the same space for the switches, knobs, display etc control features in the front panel, so, for example, perhaps the pcb connectors should be laid out differently or some features are more desirable than others.

Oh, one other thing you mentioned. About hinging things. There are a lot of wires going to the VFD and some of them are pretty stiff. Likewise, the motor and power wires are very stiff. I would think that hinging such that wires have to move would NOT be good. Things come loose or break and it is not always obvious and they may short out. You also mentioned turning the VFD. I did this and it works fine.

I also wanted the air that is being blown through the VFD heat sink to exit in the opposite direction (to cause flow in the enclosure across my electronic-brake resistor) and the little fan that is built into the VFD does flip right around just fine. Turns out the electronic brake never gets hot anyway. There is only power being dissapated in the resistor when the VFD is braking the motor. It might get warm if you were rapidly starting and stopping the motor and that never happens on our lathes. At least I am not familar with any application where this is happening. People do not seem to understand that this braking resistor only gets warm if the load is hugh and the VFD is being use to control dynamic speed changes. Things like this happen in paper mills etc. where large rolls of paper are being speed controlled to transport webs without breaking them. I have not seen any lathes the size of ours that would even ever be run like this. Hence, the 300 and 400 watt resistors are way over kill.

 

[yarm2111]

Thanks Dave, all good points. I already ordered enclosure for tach display, not the same Mark linked, but about same size. May order another one to accommodate both tach and voltmeter, but this is not a priority right now.
Yes, hinged configuration is questionable. See attached picture, it will be about inch or two higher then shown. I don't have wires and cables yet, coming tomorrow and I will evaluate this design. I'm thinking if I attached clamp to hold harness at the bottom corner of the VFD it would provide some strain relief. It also will be close to hinge axis. And hopefully I would not need to swing VFD after everything is tuned. Wishful thinking maybe?
Mike
sorry, pic is sideways

 

[B2]

Yes Mike, When I was doing mine I changed my mind several times and so I have several never used spare parts. And, yes, once you have things set up the way you want them there is seldom a need to get into the enclosure.

I do not understand your circuit design yet, but what you have certainly looks neat. The VFD is normally mounted with the heat sink against a flat surface. This is needed to constrain the fan's air flow inside the heat sink. I cannot see the edge of the heat sink so I am mentioning this. I bolted a mine to a 1/8" thick Al plate to accomplish this. Is this where your hinge is located? If you look at my design again you will see my VFD orientation such that the display is upward. I put a clear cover on my enclosure and all I have to do is look around the back of the lathe and I can look down and see the VFD display.

It looks like you have lots of room for things at the top (right hand side of the picture) of the enclosure. The relays really are big and take up lots of space. Most of them do not carry much current do they, so could be much smaller?

Dave

 

[yarm2111]

Dave, I don't have hinge yet. VFD just sits there on the bottom of the enclosure, just to show planned location. The VFD will be mounted on a .25" aluminum plate hinged to the enclosure lip just next to the gasket. I'm waiting for my cables to arrive tomorrow to see if my plan is feasible.
Yes, the contactors are big and I only use auxiliary contacts. But they already have all interlock logic from the factory and I'd like to keep them for now. In the future I can replace them with much smaller relays and just keep the logic.
Mike

 

[yarm2111]

Looks like my hinged WJ200 idea may work fine. I got 12/4 shielded cable connected and can swing VFD easily. And I was able to put EMI filter behind it too, no wasted space.

Still waiting on a motor to arrive from eBay, meanwhile installed joystick, E-stop, and pot on the front panel. Very tight fit there on the bottom of the headstock cavity. All wired and works with existing single phase motor. Jog now works in both forward and reverse.

I keep fine tuning schematic. Looks like I don't need to replace foot brake switch, instead I will use contacts available on the KA (enable relay).
Here is updated schematic Rev.1.
Mike

 

[B2]

Hi Mike,

Looks too neat to be true!

You could have a stronger wire strain relief at the VFD mount plate to prevent twisting at the wire screw down tabs.

I might have mounted the door on the left hand side so that you could open the door and see the VFD while standing at the end of the lathe.

I was thinking you were going to use the VFD intelligent inputs for wires. While these wires are smaller and have push in connectors, they are not all that strong. So you would want strain relief for them as well.

Dave

 

[yarm2111]

Thanks Dave, looks like it is going to work. Left side has less clearance because transformer there.
I'm wiring 240VAC power and intelligent inputs now. When done I will work on strain relief. I have one shielded cable from the pot and the other one from all other controls. With this cable, not sure how to route - 4 wires go straight to the VFD, 2 other have to go to the relays and then after relays 3 wires coming back to the VFD. It complicates shielding and probably would require some splicing which I don't like. But it is unavoidable, just not sure do it on the VFD, or route all to the terminal board first and then to the VFD?
Mike

 

[mksj]

Would not have used shielded wires on such short run, they can cause issues if the grounding is not done properly. You can extend the ground wires and have them go to a star or central ground plate only on at the VFD end for control wires. The purpose of the freerun command is to be active only when the foot brake is applied, so it doesn't fight with the VFD braking. Releasing the brake should allow the VFD braking to occur as well as pressing the E-Stop should revert to stage 1 braking (fast stop). Release of foot brake breaks the 24VAC power contactor latch and should not allow restart. Maybe I do not follow your schematic, but I would not want the chuck not to brake quickly when the E-Stop is pressed or the foot brake is released.

You use ferrules on the control wires typically 18-20AWG, give a small tug once pushed in they should be secure. To release them, push the orange release tab push the ferrule in and then pull out. Just pulling they are like a hook and can get jammed in place. You can secure the cables to the VFD mounting plate with zip ties or nylon cable retainers. I see no reason to look at a VFD once mounted,, you set the speed pot range for the RPM range of the machine and the operating window of the motor. A tach tells you the spindle speed. There are also other factors as to the gear train operating speeds and lubrication. The factory VFD model is designed differently then the standard gear head.

 

[yarm2111]

Mark here is my thinking - the KA enable relay is always energized unless E-stop or Foot brake are activated. So it's NC contact in the free run input will be open and VFD brake is enabled. If I press Foot brake KA drops and it's NC contact sends +24V to VFD input 6 to free run. I assume spindle would complitely stop any time I use the Foot brake, so free run or VFD braking it is irrelevant.
Now, if the E-stop is pressed +24V power is removed from all VFD inputs. My understanding was that VFD would apply braking. Is it correct?
I did have redundant E-stop contact in the VFD 6 input, it is not needed and removed in the updated schematic.

 

[mksj]

KA 21 and 22 is shown as part of the AC 24V circuit so would need to be a separate set of contact connections, if for some reason you release the foot brake or cannot complete hard braking then I would want the VFD braking to kick in. In addition the belt guard and chuck cover are tied into the same circuit if used, not a good idea to put the VFD into a free run if they trip.

Correct, if the P24 is interrupted then it would disconnect the free run command. USP should be a jumper from P24 to the programmed USP input, no need to go through the E-Stop. Other VFD's just have this as a programmed option, not as an input, they also have an emergency stop input and it has a separate braking time, which is what I use with the E-Stop NO switch block as well as interrupting the run inputs and dropping out the power latch relay.