Motor Taps Delta/Wye?

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justin

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I am currently working on a greenhouse that is manufactured entirely in Israel. There are 6 motors for shade curtains. The syatem supplying the building is a 120/208Y 3Ph System. I hooked up the motors correctly according to the diagram sent with the motors which was typical for a low voltage 3 Ph motor tap for a Y system. When we tested the motors originally the motors ran fine but were unable to completely handle the load(they stopped half way up). when we contacted the rep from Israel he said we needed to hook up the motor as if it were a Delta system and when we did they worked perfectly. Problem being that i can't understand why! Same voltage just tapped as if it were a delta system when it is actually Y. if i were to do this on a motor manufactured in the US what would be the result?. any info would be appreciated!!
signed, completely confused!!!

[ October 01, 2003, 09:18 PM: Message edited by: justin ]
 
Re: Motor Taps Delta/Wye?

Bennie
A 3-phase motor that can change from a Y to a delta would be a 9 lead wouldn't it?
Of course there are these new 12 lead Eco motors but the same would still apply if you didn't use the soft start winding.

I thought Israel used the European voltages and frequency's?
 
Re: Motor Taps Delta/Wye?

You have to have 12 leads to change from wye to delta on a dual voltage motor.

The type of supply system (delta or wye) has no bearing on how you connect the motor. You just match the supply voltage to the motor voltage. A delta supply can run a wye motor or visa versa.

Don
 
Re: Motor Taps Delta/Wye?

A 3-phase motor that can change from a Y to a delta would be a 9 lead wouldn't it?
Click to expand...
If a three phase motor is "delta-wound", that is, designed to operate with the three windings delta connected, it will not operate correctly if the windings are wye connected. Each phase would get only 58% of rated voltage, and torque would be lowered.

Similarly, a wye-wound motor mistakenly connected delta would have the winding voltage increased by the factor of 1.73, and would be damaged.

There are motors designed to be started with the windings wye connected (for a few seconds), then changed to delta for running.

Most general purpose (not multi-speed) three phase motors manufactured in North America fall into one of these categories:-

3 leads - single voltage - 208 or 575 volts.
6 leads - single voltage - 208 or 575 volts for wye-delta starting.
9 leads - dual voltage 230/460 volts
12 leads - dual voltage - 230/460 volts for wye-delta starting.

BTW - Israel's standard is 230 volts, 50 Hz.
Could one assume that equipment intended for export would conform to the standard of the country the equipment is exported to?

Ed

[ October 03, 2003, 12:11 PM: Message edited by: Ed MacLaren ]
 
Re: Motor Taps Delta/Wye?

Ed correct me if I am wrong, you are taking about low voltage connection on dual voltage motors?
 
Re: Motor Taps Delta/Wye?

you are talking about low voltage connection on dual voltage motors?
Click to expand...
Not sure what your question is.

The 230/460 volt motor can be used at either voltage with a wye-delta starter, if it has 12 leads.

The only reason (that I know of) for specifying a 12-lead motor would be for use with a wye-delta starter. Don referred to that above.

The standard 9-lead, 230/460 volt motor is permanently connected either wye or delta, depending on other design factors, internally, and cannot be easily changed in the field. The 9 leads are provided for changing voltages.

Ed

[ October 02, 2003, 01:26 PM: Message edited by: Ed MacLaren ]
 
Re: Motor Taps Delta/Wye?

Ed there are 6 lead motors that are dual voltage WYE start and Delta run. On 9 lead and 12 lead motors the connection on the high side are the same,4&7 5&8 6&9 and so on. On the low side of the 12 lead motor there is a difference on the connection between WYE and DELTA. Thatis what I was asking if that was what you were taking about?
 
Re: Motor Taps Delta/Wye?

to answer some ?'s, there were only 3 leads. i was told the motors were tested Y/360V in israel @ 50hz. I have since heard that there can actually be a difference in the torque rating of the motor depending on the internal windings and how it is tapped. definitely something new to me, and i am still interested in any other info or other similar experiences. i appreciate what has been posted so far! justin
 
Re: Motor Taps Delta/Wye?

to answer some ?'s, there were only 3 leads
Click to expand...
Justin, I'm curious.

What changes were made to the motor connections, to make them work properly? You said the motors only have three leads.

Ed
 
Re: Motor Taps Delta/Wye?

rpmlube,
Ed there are 6 lead motors that are dual voltage WYE start and Delta run.
Click to expand...
I don't see how that is possible. Can you provide any details?
Don
 
Re: Motor Taps Delta/Wye?

Check out figure 7.171, and 172 in the American Electrician's Handbook. Allen Bradley Star-delta motor starters.
 
Re: Motor Taps Delta/Wye?

Bennie,
I'll have to look at home as I don't have that book here at work. I can see single voltage wye/dela with 6 leads but not dual voltage. With 6 leads, you only have the ends of 3 coils, how can you connect this to two different system voltages?
Don
 
Re: Motor Taps Delta/Wye?

Don: I have a feeling there is more to this issue.

208 volts is rare for a star/delta start motor. I am not aware they exist. Small motors are not star/delta started. This appears to be small motors.

I am guessing that the running problem was the low voltage.

Was the supply changed from 208 wye to 240 volt delta?

6 leads from a motor are only for single voltage.

T-1 to T-4 is phase A to B.
T-2 to T-5 is phase B to C.
T-3 to T-6 is phase C to A.

Star point is 4,5,6. line is 1,2,3,

Delta connection is 1,6 is phase A. 2,4 is phase B. 5,6 is phase C.
 
Re: Motor Taps Delta/Wye?

Bennie,
I think that there is some confusion in this thread. The type of supply system, wye or delta, has no effect on the motor connections. The connections to the motor are based on the supply voltage. If you have a 480 volt wye sypply system, the motor is connected exactaly the same as when you have a 480 volt delta supply system.
The wye/delta connections in the motor are used to reduce the starting load on the supply system and as you stated would not be done on a small motor.
Don
 
Re: Motor Taps Delta/Wye?

Consider the standard 9 lead, 230/460 volt, 3 phase motor. Unless you "ring it out" with a continuity tester, you can't tell if the manufacturer connected the windings wye or delta, and in fact, there is no need to know, as it cannot be changed anyway.

The choice of connection is the manufacturer's, based on engineering principles.
For example, a high voltage, low current motor is almost always wye-wound, so that the phase winding coils only have to be insulated for 58% of the line voltage.

In contrast, a low voltage, high current machine is most often delta-wound, so that the phase coils carry only 58% of the line current, and the coil wire size is more managable.

Ed
 
Re: Motor Taps Delta/Wye?

My earlier post should have read 6 leads, sorry. These motors are small FHP motors.
 
Re: Motor Taps Delta/Wye?

Justin: Then am I correct, the winding was connected in wye, and would not reach proper speed?. When reconnected in delta it ran OK?.

This suggests a low voltage condition. Is the motor rated for 230 volts?
 
Re: Motor Taps Delta/Wye?

This suggests a low voltage condition. Is the motor rated for 230 volts?
Click to expand...
It appears that the motors are delta-wound, and the windings were mistakenly connected wye by the installer the first time. When the the mistake was corrected they operated correctly.

To repeat what I said in a previous post in this thread - "If a three phase motor is "delta-wound", that is, designed to operate with the three windings delta connected, it will not operate correctly if the windings are wye connected. Each phase would get only 58% of rated voltage, and torque would be lowered."

Ed
 
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