Star delta connection of induction motor

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panthripu

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Gentlemen ,Why my induction motor is drawing 5.5 A current with no load , when connected in star And 60A when connected in delta ?
:mad:
Appreciate your views.
 
Is the motor rated for the voltage that you're applying with the delta connection? If not then the motor may be going into saturation and drawing excess current.
Did you measure the currents on each phase to see if they are balanced?
 
Dear sir
Yes , this motor is rated for 460V/60Hz and tested with same voltage in both star and delta as well. The currents are almost balanced. In start connection L1=5.2,L2=5.2,L3=4.9 whereas with delta it is L1=60.2,L2=60.1,L3=55.1
 
So this must be a wye start delta run motor. There does seem to be something amuck. I am not very familiar with wye start delta run motors, but my understanding is the current in start/wye connection should be about a third of running/Delta. Does it start ok and then run in Delta ok?
 
panthripu said:
Dear sir
Yes , this motor is rated for 460V/60Hz and tested with same voltage in both star and delta as well. The currents are almost balanced. In start connection L1=5.2,L2=5.2,L3=4.9 whereas with delta it is L1=60.2,L2=60.1,L3=55.1
Click to expand...
Back to Post 2. Is the Motor rated for a Delta connection?

I’ve only connected a few motors Delta, and only one Wye start, Delta run that I remember.

The one attempt I made to connect a Delta wound motor to Wye did not end well. I would guess the inverse is true.

eta: in a Wye configuration. 50 years ago?
 
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panthripu,

I'd suggest posting a photograph of the nameplate, or the complete nameplate data.

In delta configuration I would _expect_ higher no load current then in star configuration. But the factor of 10 jump suggests something amiss.

My guess is that the motor is _rated_ for 460V 60Hz in the star configuration, and is not actually intended for use in the delta configuration at this voltage.

-Jon
 
panthripu said:
Gentlemen ,Why my induction motor is drawing 5.5 A current with no load , when connected in star And 60A when connected in delta ?
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Click to expand...
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Yes , this motor is rated for 460V/60Hz and tested with same voltage in both star and delta as well. The currents are almost balanced. In start connection L1=5.2,L2=5.2,L3=4.9 whereas with delta it is L1=60.2,L2=60.1,L3=55.1
Click to expand...
winnie said:
... My guess is that the motor is _rated_ for 460V 60Hz in the star configuration, and is not actually intended for use in the delta configuration at this voltage.
Click to expand...
Following every one else's posts - which are all pretty good:

My guesses are:
Synchro is right on
Jon is right on

This is a 7.5hp motor, rated for 460V,
It is not intended to be used Wye-Delta Start. Nobody wye-delta starts a 7.5hp motor.

It has to be either a 6 lead or a 12 lead, which would be uncommon for a single voltage motor
Otherwise you could not connect in delta

Unless:
It I a 9 lead motor and you tried to connect it delta. And that would not work. And the nameplate would show two voltages, 480V connection and a 240V connection.

For now, stick with: It is rated for 460V and the connection will be Wye.

I'm thinking we really need some more context here.

Question:
480V, 60HZ sounds pretty North American. Most all the time, a "Star connection" is referred to as "Wye". Which makes me think, "other than North American". Just curious, where is this located?
 
electrofelon said:
So this must be a wye start delta run motor. There does seem to be something amuck. I am not very familiar with wye start delta run motors, but my understanding is the current in start/wye connection should be about a third of running/Delta. Does it start ok and then run in Delta ok?
Click to expand...
Not very likely to be a wye/star start,delta run motor based on the op saying it only pulled 5A. A motor that size would have no trouble starting across the line.

More likely it's a dual voltage iec motor and you connect it in star for 480V and delta for 240V.
 
ActionDave said:
... More likely it's a dual voltage iec motor and you connect it in star for 480V and delta for 240V.
Click to expand...
I would not think so.
480V, 60 hz sounds pretty North American - not iec
For Wye connected 480V, each coil is 277V
Connecting those coils in delta and energizing with 240V, turns a 7.5hp motor into a 5.6hp motor
 
post 3
and I should have said 460V, 60HZ
comparing 460V wye (265V coils)
connected delta to 230V
Gives about the same ratio, .75
So, IF it is a 7.5hp motor, that would still drop it to 5.6hp
 
Yeah, I thought of that, see post 12.
And that could be a mess in couple of different ways.

As you know:
In a 9 lead motor, three leads go to an internally connected 230V Wye, each of the wye coils are 138V The other 6 leads are thee coils each rated for 138V. The separate coils are connected to a parallel 230V Wye, or are each connected in series with the internally connected Wye. The nameplate would clearly show the two different connections, one marked "High", one marked "Low".

(edit to add) I'll leave a second connection mess out. It is too far out of the box - even for me.

60A for a 230V motor connected to 460V does not sound wrong. And
one could mis-interpret the HIGH/LOW connections as Wye or Delta, but the nameplate would be clear the connections are for two different voltages.

I'm stuck with:
The OP will eventually tell us - or not

the worm - curls up for a nap
 
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