2 speed motor 3 phase 380 volt motor

[AndyD]

we have been waiting patiently all these years to see andy get stumped.

TBH It's not that rare, I get stumped quite regularly. I've never worked on a Dahlander Motor installation but I live in hope.

You can fully enclose a VFD in an enclosure without ventilation but there strict manufacturer recomendations on how much surface area the enclosure must have to allow the heat to be dissipated and it must be of metal construction. The enclosure size is also relative to external ambient temperatures so if it's being used outdoors in a ventilated and shaded area then it should be a sensible size. The last drives we had to fully enclose in a plant room (44 degrees C ambient) the enclosure needed to be 1000 x 1200 x 500mm and mounted on spacers to hold it off the wall in order to fulfil the heat dissipation requirements. We also installed a small tangential blower similar to an air curtain above them just to play it safe.

[bergie]

so the enclosure for the drive would be a bit big for a portable pump on a trolley. not to mention the exd enclosure would also cost a fortune.

[Justloadit]

so the enclosure for the drive would be a bit big for a portable pump on a trolley. not to mention the exd enclosure would also cost a fortune.

But Bergie the enclosure along with the VSD would be far cheaper than the R45K you mentioned in one of your posts. Being portable, does this not make the extension a challenge to maintain in a hazardous area?

If it is variable pumping output you require, then a loop back valve system may be a cheaper solution with a single speed motor.

[bergie]

i think the enclosure for the vsd would be too big and impractical. the customer can decide,they have big budgets. their mechanical engineer doesnt have an easy mechanical solution either.

[5barware]

Please check the drawing. I upload many times. I do not know whether I can upload successfully this time.

[bergie]

looks correct,although i'm not sure why the overload contacts are on the star point

[5barware]

looks correct,although i'm not sure why the overload contacts are on the star point

It should be on the star point. It is a 3 phase motor. Each winding powers on independently. If the overload protector is just on one winding, when overload happens, the protector just can cut off one winding power. The other two windings still power on. Then the motor can still run. So the protector must be on the star point, when overload happens, the protector can cut off all the windings power once.

[bergie]

an overload relay just switches the contactor off and all windings have no power. the star point of a motor can be connected to neutral,but doesnt need to be

[mikilianis]

Hi a quick sketch of how it should be wired up I did the power circuit and the control circuit Two Speed Motor Circuit.pdf

[5barware]

an overload relay just switches the contactor off and all windings have no power. the star point of a motor can be connected to neutral,but doesnt need to be

I can not understand what you want. And what is the problem? I think it is ok design like this.