Three phase motor question.

[Pat Tester]

I have been asked to manufacture a control panel for an automated batch
feed mixer. Pic control unit conects to weigh bridge with 8 dil relays for
auger control. My question is this, one of the motors (the first one I've looked at) has terminals marked 1,2,3 and N. 1 to 3 are the phases N has the other end of the three windings connected together. I presume this makes it connected in STAR.
Why is the terminal marked as N ? should the star point not be connected to
earth The motor does looks old

regards Pat

 

[adnarim]

not sure about the N terminal, probably a universal terminal block that manufacturer uses in other types of motor,but the star point should definately not be connected to earth,this should always be on a free terminal(in this case N ),earth terminal is for earth conductor only.

 

[OilBeDamned]

I have been asked to manufacture a control panel for an automated batch
feed mixer. Pic control unit conects to weigh bridge with 8 dil relays for
auger control. My question is this, one of the motors (the first one I've looked at) has terminals marked 1,2,3 and N. 1 to 3 are the phases N has the other end of the three windings connected together. I presume this makes it connected in STAR.
Why is the terminal marked as N ? should the star point not be connected to
earth The motor does looks old

regards Pat

Are the terminals linked out? And if so in what way?

Generally in all the older motors iv came across its been with copper links.

If the secondary terminals are linked out together its Star, if the terminals are linked out between the primary and secondary terminals then its Delta.

Hope this helps

 

[adnarim]

Hi,

see link below,some motors are internally connnected in star etc,within the stator body/winding.
http://www.rotor.co.uk/technical_support/star-delta.pdf

regards