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Variable frequency drive for high speed spindle

Variable frequency drive for high speed spindle

Variable frequency drive for high speed spindle

(OP)
I operate a CNC router table with a high speed spindle. I'm looking to upgrade to a new spindle but need to know if the variable frequency drive I currently have will work with this new spindle.

The new spindle has the following stats: 300Hz, 1kw, 18000RPM.

The frequency drive is made by LS Industrial Systems - Starvert SV008IC5-1F

The info on their website suggests that this particular drive can reach 400HZ, but I'm not sure about the other details, especially whether or not 1kw is too high.

More info is available using this link:
  
http://eng.lsis.biz/product/product/introduce/ecatalog_viewStream.asp?catalog_id=288&;fileNum=1

Any advice would be welcome.  

RE: Variable frequency drive for high speed spindle

It looks like it isn't rated for 1kW.  This means you may not be able to run the new spindle at full speed at full load for much time.

If you don't actually push your spindle to the limits constantly it may work okay for you.  You can overload them for a bit. If a particular pattern only overloads it in an occasional move it could work.   You want to do everything you can to keep the drive cool.

Alternatively 1kW drives are pretty inexpensive($200~350) and you might just want to upgrade your drive.

I've been doing acrylics, PVC, ABS, and aluminum lately. What do you route?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Variable frequency drive for high speed spindle

(OP)
I'm wondering if the 0.75KW motor rating - as shown in the PDF manual - relates to the motor within the frequency drive, and not it's output. Does anyone know if a frequency drive has a motor? My knowledge of these devices is quite poor.  

RE: Variable frequency drive for high speed spindle

There may be a small fan motor inside the drive, but its rating would be much lower and not specified.

The motor rating shown in the PDF manual is the rating for a typical motor that would be controled by the variable frequency drive (VFD). In order to avoid overloading the VFD, you must also not exceed the VFD's full load current rating (FLA), 5 amps. It is possible that you could operate a 1kW motor without exceeding the 1.8 kVA, 5 amp output rating. That might still overload the input section of the VFD, but if there is no warning against using a motor larger than .75 kW, I would go by the output kVA and FLA ratings rather than the motor kW rating.

The motor voltage rating must also match the output rating of the VFD. The PDF manual has a major unfortunate error in listing the output voltage as "Single phase, 200 to 230V." The output is actually 3-phase and the voltage would range, inproportion to output frequency, from zero to the connected input voltage, 200 to 230 V. The motor voltage should match the available input voltage supply.

RE: Variable frequency drive for high speed spindle

(OP)
Is it not possible that the 0.75KW relates only to how much power the frequency drive needs to run and not it's output. I have looked at a few other makes of frequency drive of a similar size and they do, as far as I can see, have a kw range instead of being only suitable one power rating.

I am extremely surprised to learn how much a pain it is just by getting a slightly more powerful spindle. I mean it doesn't half sound complicated. How easy is it to change the settings on these drives? I've looked at the operating manual for the Starvert drive and it goes on for ever. As someone who has very little knowledge of the electrics on a CNC table, who would be best person to get in to sort this out?      

RE: Variable frequency drive for high speed spindle

In the catalog, the motor rating entry of the specification table is intended provide to a quick estimate of what motor rating is can be connected to each model. The output current rating is the real limiting factor that determines the maximum motor size.

A motor that is rated 0.7kW is capable of delivering 0.75kW of mechanical power to the load. The maximum input electrical kW from the VFD to the motor will be determined by the motor efficiency. The maximum motor current is determined by the kW, voltage, efficiency and power factor. However, the rated current should be marked on the nameplate and listed in the catalog. That is what you need to check.

On some VFD brands it is not too difficult to change settings. Some have a quick setup guide that covers the items that are most likely to need changing. Some brands are more difficult. Anyone who has ever changed settings on any brand would probably be of some help. I have gone through the manuals and changed settings on 20 or 30 different VFD models. I will see if I can help by posting here. Do you have complete nameplate data for the motor? Have you actually purchased the new spindle?

RE: Variable frequency drive for high speed spindle

Find someone local with a technical bent. Pay them.

Keith Cress
kcress - http://www.flaminsystems.com

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