Nardini 1440E VFD Conversion advice.

[ajpiers]

I just acquired a Nardini 1440E with lots of tooling and everything seemed to be functional under 3 phase power.
Can anyone confirm that the motor would be 6.3HP/4HP 2 speed motor (nameplate, and electrical diagram attached)?. My plan is to use a VFD wired to the motors' low speed and bypassing the highspeed altogether. What would the following basic motor parameters be (when only using low speed)?:
power = 4HP???
voltage = 220
frequency = 60hz
speed = 870rpm???
Current = 17.0???
I already have a HuanYang 7.5HP Vector VFD from another project. Apparently the VFD has an 'internal braking unit'. If so, can skip using a breaking resistor and just disconnect the motors electromagnetic brake?

I hate to rewire a perfectly working machine, but don't see away around without buying an expensive RPC.

I'm a lathe/VFD novice, so any help would be great!

 

[jackalope]

I have the same machine but mine is 440v. I can’t help with a VFD and instead use a RPC and step up transformer and it works flawlessly. I have tons of tooling for mine. The relatively obscure D1-5 spindle is really the only downside but even that isn’t bad.
You will love this machine. I’ve had mine quite awhile and it is a pleasure to run. Extremely well made by a bunch of German tool makers down in Brazil.

 

[ajpiers]

I've been looking for ~3yrs to find a high quality lathe locally. Finally found this and very excited to get it running. Appreciate the heads up about the spindle. Looks like a new 15HP RPC would cost me >$1500 and take up a lot of space... Going full VFD conversions to get soft starting and continuous speed is nearly free for me.

 

[Brandenberger]

Your original post suggested wiring to the low speed windings of the motor. If you do this you throw away the top speeds of the machine, why?

You also suggest abandoning the braking system of the lathe and using whatever is in the VFD. You really need to know whether that solution would have sufficient braking capacity and duty cycle for your needs. I’m betting an internal braking system in that unmentionable VFD may not. Who knows if that drive supports a sufficiently large external resistor?

Perhaps you should draw up your planned wiring of the machine, addressing all the control aspects (fwd, rev, estop, braking, coolant pump). Depending on how you do it you probably need to add some components (eg more contactors).

 

[ajpiers]

Your original post suggested wiring to the low speed windings of the motor. If you do this you throw away the top speeds of the machine, why?

The motor has 6 wires powering it, 3 for each speed. I thought I would need to somehow change motor parameters in the VFD to change which motor speed to use and would require using contactor(s) to switch connection to the VFD. Not sure if I could or how I would program the VFD to do that. Seemed just using VFD for additional speed control was simpler.

I'll reconsider using the unmentionable VFD in favor of a good Teco, Hitachi, or Yaskawa etc.. Would I need to de-rate the VFD if it's designed for split/single phase input? Is the sensorless vector features important for braking or some other benefit?

I was considering basically just supplying existing switches with 10V - 24VDC and wiring them to VFD control inputs and program the VFD. Putting together my attempt at a wiring diagram that shows more of the details.

 

[jackalope]

He mentioned "expensive" and "RPC" in the same post. Sounded bassackwards, to me.

I'd bet the cost over even only five year beats a <not allowed to even mention> alleged VFD... including replacement cost of the motor it ruint.. that an RPC won't harm atall in 20-plus years of running.

Very good point. The RPC also allows other machines to be run but I’m assuming he knows this.
I’ve had zero issues with my over sized 30hp RPC that has less than $500 total into it. Fires up fine on 50amp breaker too. If the OP knows enough about electronics and VFDs then surely he can build a RPC in short order that does everything and then some.

 

[Bill D]

I have a cheap non name china made VFD with breaking terminals that go nowhere. The screw have no wire traces to carry any currentt from the VFd. They are just for show. This i. known problem for cheap VFDs. People install braking resistors and actually have not connected them even if they think they did.
Bill D

 

[GregSY]

VFD's with internal braking generally offer a SMALL amount of braking and rely on extra external resistors if you want more. Think about it.

The real culprit is the two speed motor, or at least the fact that Nardnin relied on a two speed motor to achieve all their speed ranges.

 

[ajpiers]

I really am learning as I go, and appreciate all the input. I'll keep looking for a suitable RPC locally, but this looks like the easy button for me: https://www.americanrotary.com/products/view/ad-digital-smart-series/?attribute_model=AD-15.
Shop space is priceless for me. Maybe I can shelter that outside...

 

[Brandenberger]

Qualify VFDs in that size range may also be in short supply and expensive right now. A few months back I had to shop around to even find a 5hp single phase capable yaskawa, and prices were going up 20-30% at that point. So maybe that makes the RPC option more favorable too. Add also the braking resistor for a good VFD would be another $200+.

 

[mksj]

So maybe to clarify a few things on the use of a VFD in this application.

1. The motor is variable Hp so there is no reason to run it off of the 8P (870 RPM) winding, other than higher torque, typically in this type of motor with a VFD you would use the higher speed winding. Torque remains flat below the base speed and Hp drops in a linear fashion, There is no reason to use the VFD for both windings and the added complications.

2. You would need a 10-15Hp 3 phase input VFD (minimum 30A output) run in derated mode for a single phase input amd a DC buss choke. So something like the Yaskawa GA50U2042ABA OR GA50U2042ABA GA500 Microdrive would be in the $800-1000 range. Tecos, Hitachi;s, etc. are in the same price range. The noname Chinese ones, their single phase 10 Hp models are very questionable, and often will go up in smoke. Their connection terminals do not match their power ratings. End of the day no cost savings when you get into this VFD's in this size range vs RPC. If you need to go low budget with a decent VFD, the Fuji drives are an alternative. You need to check the derating for single phase and that it is in constant torque mode and duty level, they are all very different.

VFD, 15hp, 230V, 3 Phase, 47A, Compact Micro Drive

VFD, 15hp, 230V, 3 Phase, 47A, Compact Micro Drive, Easy To Use

www.wolfautomation.com

3. Braking, at this size range you would need a fairly substantial external braking resistor for a VFD, the internal one cannot dissipate both the current and heat. So added cost and space. In addition, in many applications where a machine has a mechanical and or electro-mechanical brake, you would use this option and put the VFD into a free run mode/no braking when operating say the foot brake. Depends on the application.

4. An RPC 15 Hp control box can be had for around $300 and a decent idler can be found for not much, it is pretty much plug and play. It will draw more power and in some areas the size Hp motor hooked up to the grid can be limited by the power company. You can locate it elsewhere or get a sealed TENV 1750 motor which are very quiet. End of the day VFD is going to cost you more if done decently, but there are features of the VFD that may be desirable. You may be able to find a Phase Perfect or some variant offshore brand that provides 3 phase, but typically will cost much more. If you plan on multiple 3 phase machines that may be an reasonable option, despite the high upfront cost.

4. It is not just a factor of connecting a VFD as a power source, there are many ancillary costs that add up and they require modifications (and space) for them to be installed. You need to modify interface wit the existing controls...... It is all doable, but it is time and money, and some times some head scratching to get it working correctly AND safely.