motor nameplate specs confirmation?

[mikekilroy]

I have a rather unique motor nameplate and I would like to double check if my interpretation is correct. This motor has 3 output contactors and I am proposing to throw them all out and simply run this motor in one of its 3 potential modes to get highest performance over the whole vfd speed range; I think the manufacturer of this motor / drive combo missed the boat in how they applied it and made it much more complex than needed, at same time reducing the motor capability by a factor of 2-4 in some cases - I have an idea WHY they may have done this but think it is was an unwise decision.

In the wiring diagram, connector 1, 2, & 3 on motor are phases u,v, & w. each phase is 2 separate windings and they are from A-B & C-D in each connector.

I do not want to give any preconceived notions so will withhold my already written analysis until I hear from others here. I am a little concerned that if my analysis is wrong I will leave a very large aerospace machine unusable and that is not an option!

http://www.KilroyWasHere<dot>com

 

[mikekilroy]

It took me a while to see too so should bring up that the wiring diagram shows and states delta but the nameplate clearly shows wye specs.... and this is a matched set (motor & drive).

http://www.KilroyWasHere<dot>com

 

[jraef]

Looks to be what is called a "Dahlander" motor connection. If you are in the US, it's the same as a 2 speed 1 winding Consequent Pole connection, which gives you constant torque but less shaft power at the lower speed, as reflected in the nameplate. So for a VFD connection, you can just connect at the high speed pattern and it will do the same.

Qualifier; I'm on my iPad so I'm not double checking this against my stored data base, but it looks from memory to be this way.

"Will work for (the memory of) salami"

 

[mikekilroy]

1) Anyone know what the T means on the nameplate? Y and YY are easy but T? Twin Y? If so, why use both on the same nameplate?
2) Since motor nameplate says 290V in Y configurations, do you agree that run Delta on the drive shown, its base speed voltage becomes 290/1.73=167V & current goes up same (so the 94a becomes 128a)?
3) I agree it may be Dahlander style rather than double delta due to the 1/2 speed & 1/2 power rating shown, but I have never heard of a Dahlander actually being wired in double delta - has anyone else? And would that effect the ratings or torque output?
4) For a Dahlander winding I think the current flow is reversed in one of the phase windings for the low speed winding combination while it is same direction for the high speed in both windings? With this motor wired double delta, I don't see reversed current in 1 of each phase coils?

http://www.KilroyWasHere<dot>com

 

[mikekilroy]

I asked for & received additional info on motor - had them plot speed, volts out, hz out, in both series delta (001) and parallel delta (100) contactor settings (they did not include motor current or speed).

Comparing motor freq to output speed, I see low gear is about 7.5:1 ratio, high gear 1.9:1 ratio and there is no consequent pole Dahlander pole change going on - it stays 4 pole through both delta and double delta contactor changes....

Additionally, calculating v/hz, it appears the series delta gets to 400v about 50hz (8v/hz) but the parallel delta gets to 400v about 100hz (4v/hz)(so 200v@50hz 'base speed.' This would jive with the 290v Y motor rating (wouldn't it be 290/1.73=167v@50hz delta)? So the series windings each get 200v@50hz as expected, but they doubled the HP in parallel delta by using the available voltage?!?

Even with this doubling of HP, torque output should be identical for both configurations so I cannot see ANY reason to not just strip these 9 contactors out of the machine and KISS hooked up as 0-400v 0-100hz double delta winding.

Does anyone see a flaw in this?

www.KilroyWasHere<dot>com

 

[jraef]

I believe the "T" is the Italian use of what we call "Delta", but they use T as in Triangolo (Triangle)

"Will work for (the memory of) salami"

 

[mikekilroy]

It is apparent this motor is not Dahlander wound now; same speeds at same freq for both delta Y double delta (series delta/parallel delta).

Has anyone ever had experience with series_delta / parallel_delta and why one one switch between them?

http://www.KilroyWasHere<dot>com