Wye-Delta Two-Speed Control

[JesperMP]

Two nameplates, why ?
Even if it is two-speed it is one machine and one terminal box. So I doubt that (but strange things happen, so maybe).

Only one speed 1760 RPM at 60 Hz is mentioned, so it seems to be single speed by the name plate.

One mus trust the nameplate. It says 208-230V and 460V, and the diagram in the terminal box says 230V and 460V, so they correspond with each other.
There are 2 sets of windings, and they are connected in parallel D for 230V and series D for 460V. So it is NOT Y-D ! The difference between 230V and 460V is 2x not 1.7x as with Y-D. The voltage difference is by voltage divider via the windings in series.

I have attached a small sketch that shows how I interpret the motor termal diagram.

One thing, at first it seemed to me that the two connections were the same except for the links between 6-12, 4-10, and 5-11 in 230V mode were removed in the 460V mode, but at second look, they have rearranged the order of the terminals.
Very unintuitive ! And I guess that at least one of the diagrams does not look like the physical arrangement of the terminals in the box (very bad, it can/will lead to connection mistakes).

It is not a super-big motor, just 20HP so maybe you can just start direct without Y-D starter.

The motor starter diagram from before is almost certainly for a two-speed motor. So does not match this motor.

 

[JesperMP]

After reading a bunch on the subject I think what I'm really looking at is a two speed, single winding motor, that will be running with variable torque (pump application).

How do you come to this conclusion ?
The motor name plate only mentions one speed 1760 RPM.

 

[keshik]

Jesper - is it not one of the touted advantages of having a 12 lead motor the ability to configure wye or delta as you wish when you install it (pretty much all of this stuff is new to me).

Here's another question as well - what makes a two speed, single winding motor different from a single speed, single winding motor?

 

[keshik]

How do you come to this conclusion ?
The motor name plate only mentions one speed 1760 RPM.

Part of the issue is that I've been confused as to what I've been starting with and actually trying to do. I think that I confused a lot of people by originally talking about a wye/delta start sequence when I should have been asking about a two speed motor. Two days ago I didn't know the difference.

So let me try this again. I believe that the electrical schematic indicates that they are going for two distinct motor speeds (as opposed to a lower current start). I know that functionally they are going for two speeds as I just did a startup on a similar machine that had a VFD instead of this mess and that was the case there. Pump at low speed for a set period of time and then move to high speed to build up to a maximum pressure.

Now, for this particular machine, there's a few things at play. I'm not sure if the original designer and manufacturer of this machine (in Italy) provided this motor. It may have been something that our customer (we're doing some retrofitting on this machine as a local company) just provided without knowing there is something special about needing to intentionally purchase a two-speed motor. I've been operating under the assumption that this motor will actually work in this application and therefore might have been bending my facts to support that assumption.

Really, what I should do next (after I go and get a few hours of sleep) is call the motor manufacturer and see if I can find someone who can give me an answer that sounds believable. I'm sure there's several more things I'm missing.

 

[JesperMP]

You are right. I missed that the number of poles changes, so the speed will also change.
I guess that the 1760 RPM refers to highest speed then.
And the motor starter from post #1 CAN be used.

 

[Gil47]

Here is a link to a spec sheet.
My reading of the sheet may differ to yours,
so I will leave you to draw your own conclusions from what is supplied


http://www.naemotors.com/wp-content...Crusher-Design-Motors-Brochure-June-20114.pdf

 

[pal]

Please disregard the terminal assignment Igave in my previous post .
I agree with Califflash . This is a single speed motor sometimes refered to as universal . If being used without a VFD , it can run from 50Hz or 60 Hz supplies and is flexible in the voltage ratings .

A 2 speed motor , I believe in the States it is sometimes known as a consequent pole motor , has double the number of slots of a normal motor of the same rating ( compared at the higher speed rating of the 2 speed motor ) . With the Dahlander connection split winding scheme , the effective number of poles is doubled at low speed and so provides an output speed which is half the half the high speed . ie high speed 1760 rpm , low speed 880 rpm . The advantage of split winding motors is that all the wihdings are used at both speeds . A motor with seperate windings for each speed tends to be much larger and heavier than the split winding motor . The advantage for the seperate winding motor is that the starter and controls are much simpler .
Motors with seperate windings have some different terminal numbers , typically you will find T13 to T17 on the terminal block .

Other posters have mentioned using a VFD , and I agree .
Paul

 

[pal]

Sorry , I forgot to mention the connections to the motor. The supply to the motor goes to terminals 1 , 2 & 3 as per the right hand details for 460v. The terminal block should already have links fitted and I anticpate they are already set for 460V operation ie
1 -12
2- 10
3 -11
4 - 7
5 - 8
6 - 9
If you are using this pump in the States at 60Hz , then use the details on the left of the nameplate . I do recommend a VFD for this application since it gives you a great range of start up speed / torque flexibility - you can select different start up speeds and ramp times .

Good luck ,
Paul

 

[pal]

Having reviewed my posts , I realise I did not make clear the difference between star / delta and 2 speed motors - I guess it's old age .
A star / delta starter reduces the inrush or surge current to approx. 2 !/2 times the full load current by applying a reduced voltage and therefore reduced torque to the motor . The motor will still achieve the full speed if lightly loaded . A direct on line starter will peak at 6 -7 times the full load current when starting loaded .
A 2 speed motor will run at low speed ( half the full speed ) by doubling the number of effective poles and can run continuously at this speed .
As to the the wiring sizing and type along with protective devices - I'm sorry I can't help , they have to comply with the Alberta regulatory requirements . I' m sure other members can help if you need it.
Paul

 

[milldrone]

I'm with Gil47,

Search the PDF he linked to with the part number in the pics on post #12.

Draw your own conclusions from there.

 

[Mill_Control]

I'm not sure if the original designer and manufacturer of this machine (in Italy) provided this motor.

It's highly unlikely a european OEM supplied that motor.

 

[keshik]

It's highly unlikely a european OEM supplied that motor.

Considering the name of the manufacturer?

Anyways, I ended up calling the manufacturer and nope, it's not multispeed, and in fact, they don't even make any that are. Time for the customer to decide what they want to spend money on - a VFD or a proper two-speed motor.