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.

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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.

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

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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

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Thanks, Nick

MichaelG.

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