HV vs LV connections with Delta and Wye connections on motor

[philly]

I have a motor that I believe is a 480V motor and will be installed on our 480V system. The motor nameplate lists the motor voltage at 260V/460V with the associated current for each voltage value. The motor is a 6-lead motor and shows configurations for both wye and delta.

My question is, if I am feeding the motor with 480V should I use the delta or wye connection on the motor. I am thinking I need to use the delta connection but am unsure because of the LV and HV terminology. Does the HV connection which is shown used with the wye connection get used for a voltage higher than 480V? Or is the high voltage connection choses when you have 480V avaliable?

 

[don_resqcapt19]

Take a look at this thread. You really can't have a 6 lead motor dual voltage motor with a voltage ratio of 2:1. The voltage ratio for a wye/delta is 1.73:1.

 

[philly]

Take a look at this thread. You really can't have a 6 lead motor dual voltage motor with a voltage ratio of 2:1. The voltage ratio for a wye/delta is 1.73:1.

The voltage on the nameplate of 260/460 is not a 2:1 but more like a 1.76:1 ratio which is close to 1.73.

 

[Jraef]

The exact wording of your nameplate is actually important here. If it says 230/460, that would make it a NEMA (North American) motor design and the configuration would not be Wye or Delta, in fact a 6 lead NEMA motor would not be dual voltage at all.

But if it really does say 260/460, or more likely 265/460, then it is likely a dual voltage IEC motor that has been re-labeled for use in the US. If that's the case, you would use it in the High Voltage pattern for 460V, which would be the Wye (Star) connections. I would not run it on 230V however, unless you use a boost transformer to step it up to at least 260V.

 

[philly]

The exact wording of your nameplate is actually important here. If it says 230/460, that would make it a NEMA (North American) motor design and the configuration would not be Wye or Delta, in fact a 6 lead NEMA motor would not be dual voltage at all.

But if it really does say 260/460, or more likely 265/460, then it is likely a dual voltage IEC motor that has been re-labeled for use in the US. If that's the case, you would use it in the High Voltage pattern for 460V, which would be the Wye (Star) connections. I would not run it on 230V however, unless you use a boost transformer to step it up to at least 260V.

The motor is a European SEW motor. The nameplate does indeed say 260/460 so its sounds like I need to wire it in a wye connection with my supply voltage of 480V. This motor is indeed a 6 lead motor with 3 windings and the nameplate shows the different winding configurations.

If a 6 lead motor is either wye or delta and cannont be re-wired between the two, then why does the motor have two different wiring methods which appear to be a delta and wye configuration with the three motor windings? It sounds like you are saying a 6 lead motor is either a wye or delta, but why have the two different configurations?

On a 480V system will the 480V supply always be ton he high voltage connection?

 

[philly]

The exact wording of your nameplate is actually important here. If it says 230/460, that would make it a NEMA (North American) motor design and the configuration would not be Wye or Delta, in fact a 6 lead NEMA motor would not be dual voltage at all.

But if it really does say 260/460, or more likely 265/460, then it is likely a dual voltage IEC motor that has been re-labeled for use in the US. If that's the case, you would use it in the High Voltage pattern for 460V, which would be the Wye (Star) connections. I would not run it on 230V however, unless you use a boost transformer to step it up to at least 260V.

If we use the high voltage pattern with a wye connection will we only develop only 58% of the torque in the motor? If our supply was 240V would we then use the delta connection?

It sounds like the connection is determined by what the winding coils are rated for. How do you tell what the coils are rated at, for a sure way of knowing how to make the connections?

 

[Jraef]

The motor is a European SEW motor. The nameplate does indeed say 260/460 so its sounds like I need to wire it in a wye connection with my supply voltage of 480V. This motor is indeed a 6 lead motor with 3 windings and the nameplate shows the different winding configurations.

If a 6 lead motor is either wye or delta and cannont be re-wired between the two, then why does the motor have two different wiring methods which appear to be a delta and wye configuration with the three motor windings? It sounds like you are saying a 6 lead motor is either a wye or delta, but why have the two different configurations?

On a 480V system will the 480V supply always be ton he high voltage connection?

NEMA motors with 6 leads are either Y or Delta, but yours is not a NEMA motor. It is an IEC motor, originally intended for use in Europe or Asia for instance. In those areas, the common voltages are either 220Y380, 230Y400 or 240Y415V, and the difference between them all is the sq. rt. of 3, or 1.732. So 240 x 1.732 = 415, or 415 / 1.732 = 240 (all are nominal). That means you can have a "dual voltage" motor by simply bringing all 6 leads out and connecting it either way; Y for the higher level, Delta for the lower.

But here in N. Am., we don't do things like that so out motors are not wound for it. Our voltage choices are generally double, i.e. 240 or 480. So the 1.732 trick, that of connecting a motor in Y or Delta, doesn't work here. What they id or your motor was to take a 220/Y380V 50Hz wound IEC motor and changed the nameplate for use on 60Hz. Motors work via a V/Hz ratio. 415V 50Hz is 7.6 V/Hz. If you apply a 60Hz power supply, then to make the ratio correct, you would been 60 x 7.6 = 456V, which they rounded up to 460V. But where the 50Hz lower voltage was originally 220V, the new ratio has to follow the same rules. So 220 / 50 = 4.4 V/Hz, x 60 = 264V, which they are rounding down to 260 in order to make it sound a little more palatable perhaps.

To answer your other question, No, you will get full torque at 480V when connected in Y, or full torque at 260V when connected in Delta. But if you connect only 240V in the Delta pattern, the torque will be reduced by the square of the reduced voltage percentage. So 240/260 = .92, squared = 85% of FLT.

 

[Besoeker]

The motor is a European SEW motor. The nameplate does indeed say 260/460 so its sounds like I need to wire it in a wye connection with my supply voltage of 480V. This motor is indeed a 6 lead motor with 3 windings and the nameplate shows the different winding configurations.

I would wire it in wye configuration.
You say it's European but neither 460V nor 260V is common in Europe. The standardised harmonised EU voltage is 400/230. Note also that the frequency in Europe is 50Hz. If your motor isn't 50Hz it wouldn't have been intended for the European market.

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[philly]

I would wire it in wye configuration.
You say it's European but neither 460V nor 260V is common in Europe. The standardised harmonised EU voltage is 400/230. Note also that the frequency in Europe is 50Hz. If your motor isn't 50Hz it wouldn't have been intended for the European market.

[

I made a mistake by saying that it was a European motor. I got confused with the fact that the manufacturer is a European company, but I'm sure as you stated the motor is intended for use in North America.

 

[Besoeker]

In those areas, the common voltages are either 220Y380, 230Y400 or 240Y415V, and the difference between them all is the sq. rt. of 3, or 1.732. So 240 x 1.732 = 415, or 415 / 1.732 = 240 (all are nominal). That means you can have a "dual voltage" motor by simply bringing all 6 leads out and connecting it either way; Y for the higher level, Delta for the lower.

Probably not. The two voltages are not commonly available as three-phase.
As I posted above, in Europe it is 230/400V.
The 400V is the common 3-phase LV distribution*. Distribution transformers for LV generally have a star (wye) secondary. The 230V is, of course, the line to neutral voltage and used for single phase loads. We don't have 230V three-phase. If a motor has six terminals brought out it is most likely to accommodate star-delta starting. Star starting, delta running. Not for two different operating voltages.

*For me at least, this seems rather less complex that practices in the US.
The vast majority of residences have just one single-phase voltage entering the premises. Lighting, heating, etc all operate at nominal 230V. Domestic appliances are all rated for that. There is only one type of receptacle.

For commercial or light industrial, a three phase four wire supply 400/230 supply may be used. Anything that requires three phase gets 400V three phase. And the 230V stuff gets the 230V phase to neutral derived from that same 400V.

Just seems a whole lot simpler than 120, 208, 240, 480, center-tapped 120-0-120, high leg delta.....etc.

 

[LarryFine]

We don't have 230V three-phase.

Well, we do, but we call it 240v Delta. What we don't have is 240v line-to-neutral.

 

[Jraef]

We don't have 230V three-phase. If a motor has six terminals brought out it is most likely to accommodate star-delta starting. Star starting, delta running. Not for two different operating voltages.

Maybe not in the UK, but they do use 230V 3 phase in NZ and Australia, and since many of their motors come from the UK, the motors are often set up to be used that way.

By the way, if you have a 380V 50Hz wound motor, the V/Hz ratio is 7.6:1. If you apply 460V 60Hz to it, your V/Hz ratio is still 7.6:1. That's why they do that. The motor will run 20% faster and actually put out more HP at 60Hz, but many OEMs just leave the power rating alone. In this case I think they put the 260V LV rating on it just to be accurate since that's how it works out, not intending for it to actually be used that way.

 

[Besoeker]

Maybe not in the UK, but they do use 230V 3 phase in NZ and Australia,

Australia was 240V single phase and 415V three phase.
http://www.westernpower.com.au/mainContent/workingWithPower/ourNetwork/Network_Vital_Statistics.html

Distribution lines take lower-voltage power from substations and ?distribute? it. Distribution lines transmit the following voltages:
o 33,000 Volt or 33 kV
o 22,000 Volt or 22 kV
o 11,000 Volt or 11 kV
o 6,600 Volt or 6.6 kV
o 415 Volt

I think has been harmonised to EU standards.


http://en.wikipedia.org/wiki/Three-phase_electric_power
A phase-to-neutral voltage of 230 V is standard in Europe and Australia.
Phase-to-phase would thus be 400V.

I'm pretty sure New Zealand is the same. We did have some dealings with a company there a while ago on three-phase PFC capacitors.

and since many of their motors come from the UK, the motors are often set up to be used that way.

Possibly not.
UK used to have decent motor manufacturing facilities but, like many other industries here, that has been decimated in recent years as more manufacturing is outsourced to India and the Far East.

In this case I think they put the 260V LV rating on it just to be accurate since that's how it works out, not intending for it to actually be used that way.

Well, maybe. If it was 460V in wye, it would be 265.6V in delta so if it was rounded to the nearest 10V, 270V would have been closer than 260V.

 

[philly]

Thanks for the responses guys. I think I have a better understanding of these motor configurations now. Heres what I think I now understand.

6 Lead Motors -Six lead motors have 6 leads brought out that can be connected in either a wye or delta configuration. However the Delta/Wye combinations are only used for a wye-detla starting scheme or when a European motor has been converted to a motor to be used in North America as Jraef pointed out above. The wye configuration will always be 1.73 times less voltage then the delta connection. Are the winginds internally in the motor connected in either configuration?

9 Lead Motors- These 9 lead motors are either internally wired in a wye or delta configuration and cannot be changed. These motors are dual voltage motors and are operated with the windings in series for a higher voltage (460V) and in parallel for a lower voltage (230V). The motor will always have the dual voltage rating on the nameplate listing the high and low voltages.

12 Lead Motors- These 12 lead motors can be wired in a wye or delta configuration, and can also have their windings in series or parallel depending on voltage. The two voltages are always listed on the nameplate for the high and low voltages. The wye configuration will always be 1.73 times less voltaage then the delta connection.

Did I pretty much sum everything up correctly? Did I miss anything?

 

[GeorgeB]

6 Lead Motors -Six lead motors have 6 leads brought out that can be connected in either a wye or delta configuration. However the Delta/Wye combinations are only used for a wye-detla starting scheme or when a European motor has been converted to a motor to be used in North America as Jraef pointed out above. The wye configuration will always be 1.73 times less voltage then the delta connection. Are the winginds internally in the motor connected in either configuration?

Ignoring the "luck of the draw" at being able to use a motor designed for one system on another (and considering the available voltages as 208-230/460, GENERALLY a 6 lead motor is said to be a single voltage winding suitable for wye-delta starting. The sqrt(3) thing applies; wye full magnetization requires sqrt(3) * the delta voltage.

9 Lead Motors- These 9 lead motors are either internally wired in a wye or delta configuration and cannot be changed. These motors are dual voltage motors and are operated with the windings in series for a higher voltage (460V) and in parallel for a lower voltage (230V). The motor will always have the dual voltage rating on the nameplate listing the high and low voltages.

I believe that a 9 lead motor is always a wye connected motor. You either series or parallel windings. The dual voltages will be 2:1 related. There will likely be some manufacturers who make dual voltage dual frequency, but I suspect this will be limited to lower power (under 10HP?) applications. I'm particularly thinking here of a 230/460-3-60 rated for use at 415-3-50 wired in the high voltage connection. You will not be able to get as much power from the motor in 50 Hz applications at the same temperature rise.

12 Lead Motors- These 12 lead motors can be wired in a wye or delta configuration, and can also have their windings in series or parallel depending on voltage. The two voltages are always listed on the nameplate for the high and low voltages. The wye configuration will always be 1.73 times less voltage then the delta connection.

GENERALLY a 12 lead motor is said to be a dual voltage winding suitable for wye-delta starting on either voltage. And in my terminology, your statement should be "The wye configuration will always be 1.73 times MORE voltage then the delta connection." I consider that a motor designed for operating delta, starting wye, to "NEVER" to be operated wye.

Did I pretty much sum everything up correctly? Did I miss anything?

To me, you summed it up pretty closely. I'd add that IN GENERAL, a 3 lead or 9 lead motor is OPERATED (but you have no control over it) wye connected. IN GENERAL, a 6 lead or 12 lead motor is OPERATED delta connected. If you had some oddball voltage at the designed frequency (say 400-3-60 or 800-3-60), you could OPERATE a 6 or 12 lead motor at sqrt3 * the normally delta connected voltage with a wye connection.

 

[philly]

O.k. so now that I'm clear on the connections, its time for the fun question? The question relating to the theory or operation resulting from these connections.

With these different motor connections I'm assuming that each winding is designed to have a particular flux density based on the votage and frequencey through the winding. For example in a 9 lead 230/460V motor each winding is designed to have a particular flux density with 230V across each winding? Since flux density is proportional to V/hz then as long as the windings are put in parallel or series to achieve the appropriate voltage across the windings.

Obviously with a wye connection the voltage across the winding is less then design and therefore the flux density across the winding will be less then design. The lower flux density will lead to a lower torque output.

 

[GeorgeB]

O.k. so now that I'm clear on the connections, its time for the fun question? The question relating to the theory or operation resulting from these connections.

With these different motor connections I'm assuming that each winding is designed to have a particular flux density based on the voltage and frequency through the winding. For example in a 9 lead 230/460V motor each winding is designed to have a particular flux density with 230V across each winding? Since flux density is proportional to V/hz then as long as the windings are put in parallel or series to achieve the appropriate voltage across the windings.

I agree with your analysis.

Obviously with a wye connection the voltage across the winding is less than design and therefore the flux density across the winding will be less then design. The lower flux density will lead to a lower torque output.

Whoa here ... a wye connection will only have a lower than design flux density (assuming design frequency) at the nameplate voltage IF the motor was designed by flux density criteria to run delta. This would normally apply on a 6 lead or 12 lead motor starting in the wye configuration ... 58% torque IIRC.

A 3 lead or 9 lead motor (inherently wye) has proper flux density in its wye configuration.

 

[GeorgeB]

Whoa ME ... there are 3, and 9 lead motors designed to operate delta connection.

Go to Baldor's website and under support select motors, then get their MN408. See pages 2-5 and 2-6.

My mistake!

 

[LarryFine]

9 Lead Motors- These 9 lead motors are either internally wired in a wye or delta configuration and cannot be changed.

Just to throw in the technically-speaking twist, a 9-lead motor is actually a 12-lead motor with the other three leads connected and inaccessible.

When run on the lower voltage, you connect the other group's corresponding three leads together, parallel the lines, and have two parallel wyes.