is this motor suitable for a milling machine

Hi , Im always unsure when i look for suitable motors and especially the electrical aspects of machine tools.But is the motor in the photo suitable to run a milling machine through an inverter??

I notice it says there is no thermal overload protection is that a big problem? 

Its a washdown motor but i like the idea of the extra protection from the environment you get with these motors as my workshop isnt exactly ideal and often gets damp .

Thanks

Edited By mark smith 20 on 26/07/2016 09:54:53

Edited By mark smith 20 on 26/07/2016 09:56:18

It's dual voltage, and from a good manufacturer

... So my answers would be:

Q1 = YES

Q2 = NO

MichaelG.

Edited By Michael Gilligan on 26/07/2016 10:29:30

All the NOT protected means is that there is neither a thermo-switch, nor a thermistor embedded in the windings to wire back to the control terminals of the VFD. Modern VFDs provided a lot of protection anyway if the motor rating information is set correctly (some can even measure/calculate this for themselves). If planning extended running at low speed, or lots of stop/start cycles in a short time, extra thermal protection might be more important.

I wouldn't be worried about a little damp (as long as your cable glanding is sound) - standard TEFC induction motors are often installed outdoors with no weather protection.

Thanks Michael good to know. Another question, these motors don`t appear to come with a terminal block ,what would be a suitable type for this?? They have 9 numbered wires coming out .

See photos.

mark

Edited By mark smith 20 on 26/07/2016 11:13:09

.

That's quite unusual ... But nothing to worry about.

I would probably use one of the better quality 'chocolate block' strips [the ones with protective leaf springs inside] to avoid damaging the wires.

Incidentally: You mention 'these motors' ... Would you mind sharing your source ?

MichaelG.

Anything that is safe and works would be fine. Start with connector strips and build from there if there is nothing available commercially.

Only twelve wire connections and three or five link connections, so not too difficult. Better screw clamp connections would be better than the usual cheap strips with screws into the conductors. Fitting good connection terminals to each wire is also safer.

The question of suitability for any particular milling machine? Yes. But not to all.

MG,  looks like a US product.  Might be OK, if you are that side of the pond, but a bit hefty to import to the UK, I would think.

Edited By not done it yet on 26/07/2016 12:02:24

I would have thought that although it is rated with dual voltages, it could still be used with an inverter.

It is common for three phase motors to be capable of being wired either star or delta. The impedance of the winding is different in either configuration. The rating plate should say if the rating is star or delta. If it does not, you would probably assume that the rating is for delta. This is how larger/older motor rating plates work, to allow for star/delta starters.

In your case the label inside the connection cover implies that the two voltages on the rating plate are for delta and star respectively. I'd say that you can use that motor with either a three phase or a single phase input inverter.

It does depend very much on what inverter you obtain to use with it. Generally an inverter with a single phase input will only have a fairly small output voltage rating. A three phase to three phase inverter would normally have a much higher output voltage rating. This is not a rule, just an observation.

To compensate and get broadly equivalent ratings from a motor at different voltages you would wire 240V delta and say 415 star. If you just want the maximum from the motor, wire delta whatever the supply. If you want efficiency and/or low inrush wire star.

There is absolutely no reason not to use a motor like yours with an inverter. You should do some simple experiments however. Get a current clamp and verify the rating plate data. You can also get thermistor protection relay packages from people like ABB automation. These can act to stop the motor in thermal overload conditions. That might be quite important with a fully sealed motor, like this. Obviously it must have poor airflow.

The connections you will have to buzz out. It looks to me like someone has written the terminal numbers on the wires. Check them obviously, but there is no reason not to use 10A marathon/choc block inside the box to make connections.

You should expect it to work out such that low voltage is the delta connection and high voltage is star connection. If it doesn't something is up.

I'd use a rigid type terminal strip rather than the soft nylon type, they are more like the material usually found as terminal blocks in motors and may be more resilient with regard to fretting due to vibration.

**LINK**

Martin

Normal method of connecting these is to crimp ring terminals to both motor & supply wires and nut & bolt them together, using both flat & spring washers. Then insulate with PVC boots held on with cable ties, or wrap with self amalgamating tape followed by PVC tape. An alternative is to twist motor & supply wires together & then apply an insulated closed-end splice crimp over the twisted ends.

I see this method of termination frequently on Korean, Taiwanese & Japanese CNC machine tools. I first came across the method while production wiring large lathes at Broadbent Machine Tools - but only on machines destined for the US. IIRC I was told at the time that it was a requirement of the American Electrical Standards that this method of termination was to be used, rather than the stud type terminal blocks European manufacturers normally fit.

Nigel B

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I think that was the style that Michael Gilligan meant. i.e. the ones with the leaf so that the securing screw does not rotate directly into and chew the the cable.

Nick

Its for a Alexander master toolmaker mill

Edited By JasonB on 26/07/2016 14:18:29

Thanks for the replies ,i will address some of the points when i get the motor in question as i will need help wiring it up, they seem good quality motors and are listed at around 400-500$US in the catalogues.

.

Thanks, Nick

MichaelG.

Mark, the wiring is quite easy based on your photo for low voltage. Join together L1, T1 & T7. Join together L2, T2 & T8. Join together L3, T3 & T9. Join together T4, T5 & T6. To do this you need a connector block with four terminals that can take two cables in one side and one in the other side.

Martin

Hi, Just received a new inverter , one of these **LINK**

Bought off ebay not from the link above.

What do i need to get this up and working?

The workshop has a consumer unit that takes mini type MCCB . Do i need a type B or C ? The manual states 20 amp.

Also cable , i only need 3 metres of each , is this suitable ?**LINK**

3 metres of 3 core and 3 metres of 4 core?

Anything else i need between the consumer box and the inverter??

Also a bit confused by what type of terminal block i need for the 9 motor wires ? Link mentioned a few posts above,why not just a normal motor terminal block or will these not work with 9 wires.....

Thanks

Edited By mark smith 20 on 03/08/2016 12:18:29

Keep a close eye (well hand) on how warm it gets. With no airflow and not even any fins on the outside I think you may be limited to intermittent use.

Mark

Type C mcb, use ramp up speed to prevent mcb tripping.

Cable shown is suitable but if you don;t use the proper glands that are listed be sure to take a tail of the protective braid into the earth terminal at source of supply and same at motor. The 1.5mm size will be OK with such low current and short lengths but you may have to go to 2.5mm to satisfy short circuit protection of the type C mcb.

You may want to fit a Double Pole isolator in the feed from the consumer unit to provide complete isolation of the supply at the inverter.

Emgee

Bazyle, states Continuos Duty on the plate but your advice should be headed.

Edited By Emgee on 03/08/2016 12:46:46

I wont know if this will be a problem until i use it ,it is continuous use rated and has a large fan on the end.