460V motor unit supplied with 380V power 5

[chef5mate]

Hi,

We have Baldor motor units, specifically models ECP4314T and ECTM4314T, with voltages rated at 460V/60HZ/3PH to replace the old cooling tower fan drive motor units. However, available power supply is only 380V/60HZ/3PH. what are the possible effects the 460V motors would have in terms of performance output and its useful life?

 

[waross]

Low starting torque and low HP. If these motors are used to replace similar HP 480 Volt motors that are fully loaded, expect burnouts.
Consider an open delta autotransformer boost arrangement to raise the motor voltage to 480 Volts.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[chef5mate]

hi, bill! maybe I didn't make myself quite clear. allow me to try it one more time...

the old cooling tower fan drive motor is 380V/60HZ/3PH supplied by 380V/60HZ/3PH utility and now needs replacement so we were looking for similar unit. a local Baldor dealer is proposing to replace this with a motor that says 460V/60HZ/3PH on its name plate. my questions is, how would a 460V motor behaves when you supply it with 380V power? what are possible effects on the motors' overall performance if you supply 380V to a 460V motor unit? both the old 380V and the proposed new 460V motor units are rated 60HP.

sorry for the confusion...

chef5mate

 

[petronila]

Hello chef5mate,

The Baldor´s solution could works fine if the motor is 12 leads and 1 Delta for 460 V,60 Hz then you can connect the motor in two wyes and will works for 380 V, 60 Hz.

Best Regards

Carlos

 

[zlatkodo]

H, Chef5mate,
What is the motor power ? How much motor is loaded?
Is there any starter ( YD or soft start)?
It's hard to say for sure, without knowing more details but in case if the motor of 460 V can start at 380 V, only consequence could be decreasing the fan speed (increase in slip).
Proposal of Petronila is best, if it is feasible.

[URL unfurl="true"]http://winding.wix.com/design[/url]

 

[waross]

If the previous motors were 50 HP or less or if the actual load on the motors is less than 50 HP, the proposed motors could work.
If you need over 50 HP to drive the fans then:

Low starting torque and low HP. If these motors are used to replace similar HP 480 Volt motors that are fully loaded, expect burnouts.
Consider an open delta autotransformer boost arrangement to raise the motor voltage to 480 Volts.

The Baldor ECP4314T is available in 9 lead, or 3 lead.and the ECTM4314T is a three lead motor.
You may be able to change the drive ratio and run the fans slower to avoid burnout.
If you need 60 HP at 380 volts and 60 Hz, that is not a standard motor in North America.
Options.
Over sized motor. About 75 HP
Have the motor rewound for 380 Volts. (Sorry, the Baldor motors look like they are already connected nine lead delta.)
Have a motor specially wound.
Open Delta Auto transformer boost.
Or, get a performance guarantee with the Baldor motor.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[petronila]

Hello

Please take a look of attached file.


Best Regards

Carlos

 

[Parchie]

@petronila,
There's no argument there when you said he only needs to reconfigure the motor from delta into a wye-connection. But if you look at the part numbers of the Baldor motors that are offered as replacements, you'll understand that those motors are pre-wired "delta", either high or low voltage (460/230V)--> 9 leads out! IMO, it's gonna be a hard thing to do.

 

[zlatkodo]

Hi, Carlos,
By the way, I would like if the winding redesign is so simple, but unfortunately is not.
I know from which reputable publications "the master formula" is taken, but I think it is too, too simplified, incorrect and should not be used in this form at all.
Try and look what you'll get if you want to do a winding redesign from 4 to 2 poles (at same F,E, Kp, N, CC ) .

[URL unfurl="true"]http://winding.wix.com/design[/url]

 

[chef5mate]

Sorry for the late responding gentlemen as I was out for a business trip...

Hi, Zlatkodo! these are what i gathered as additional information about the existing motors, "MOTOR, AC, RELIANCE BRAND, XE DUTY MASTER / XT-EXTRA TOUGH,60HP, 380V/3PH/60HZ, 6-LEADS, 1780 RPM, 364T FRAME, TOTALLY ENCLOSED FAN-COOLED, CONT. DUTY, INVERTER READY"...have already forwarded these info to Baldor for possible match up...not sure if Reliance ever did 380V/60HZ/3PH motors though, did they?

Thanks a lot, Bill! Appreciate your winding redesign formula, Carlos...i guess we'll just have to outsource closest alternative equivalent...any suggestions where we could find one without the hassle of doing all these? 380V/60HZ/3PH is european, right?

appreciate all your help gentlemen!

 

[petronila]

Hi Zlatkodo,

Yes it is a simple calculation, for that reason I have sent this formula. I know that for complex redesigns this formula is not the best but for this case can clarify the reconnection is possible and chef5mate is asking only how a 460 V motors could works with 380 V and him is not speaking nothing about some complex winding re-design.

The problem also could be solved even we use a second hand motor with same power and Frame and six leads (delta wye starting) or three leads (inside Delta conected) and we take out 12 leads or we made the internal connection in two wyes, then the nameplate will be replaced with all new parameters.

Another solution is rewinding other motor with same power and frame.

For more accuracy the best is use a redesign program and also your own data bank, the AC Redesign Program of EASA is an excellent tool that provide you the chance to analyze all important parameters including efficiency increasing and so on helping you to choose the right re-design data.

Only like an example, in South america you can find both frequencies and different voltages (230/400-50 Hz,220/380/440-60 Hz) and WEG a reputed brand, designs some of his windings to make possible this motors can works with 380 V-60 Hz (used in mainly in the border of Brazil and Paraguay) it design is based in the same : 12 leads-two deltas for 220 V-two stars for 380 V and one Delta for 440 V. Then this motor is works with three different voltages at 60 Hz and also with 380 V-50 Hz.

Thanks and Best Regards

Carlos

 

[waross]

The change from wye to delta is quite easy with a 6 lead or a 12 lead motor. With a 3 lead or a 9 lead motor, a winding shop may be able to locate and bring out the buried internal connections. This is more expensive but may be doable.
BUT, The Baldor information for these motors seems to indicate that these motors are already delta connected.
YOU CAN"T RECONNECT A 480 VOLT DELTA MOTOR FOR 380 VOLT DELTA. It needs a rewind with a larger gauge of wire.
In Western Canada, we have a mix of 480 Volts and 600 Volts. When a plant goes into shutdown for maintenance, temporary power and lighting is often supplied by rental generators. There are very few 600 Volt generators available on the rental market. The most common way of supplying 600 Volts from a 480 Volt transformer is with an auto transformer boost.
There are two choices, the wye auto--transformer boost and the open delta auto-transformer boost.
The open delta needs only two transformers.
I have run into numerous instances where, for one reason or another, the voltage was transformed twice, from 480 volts to 600 Volts and back to 480 Volts.
The big problem is to run the fans on the available voltage with available equipment.
Some Options:
1> Use available motors and of the shelf transformers for an auto transformer boost. Replacement equipment is readily available.
2> Locate 380 Volt/ 60 Hz motors, or 480 Volt wye wound motors that are easily reconnected in delta. Replacement equipment may be more difficult to locate in the event of sudden need.
3> Rewind the locally available motors for 380 V/60Hz. Expensive.
I suggest that you investigate the availability of the various options and then make a choice based on the economics, including the cost of loss production in the event that a motor fails and there is a lengthy delay getting a suitable replacement.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[zlatkodo]

Hi, chef5mate,
Still nothing is known about the starting device, the stator connection (Y or D).
Your question was:

how would a 460V motor behaves when you supply it with 380V power?

If you have some source of variable voltage and if it is technically possible, try to make the next test: connect (for short time) the old fan drive motor of 380 V to reduced voltage of about 315 V. Record the changes of currents and rpm (in %), and you'll get an answer to your question.

[URL unfurl="true"]http://winding.wix.com/design[/url]

 

[waross]

Google + Baldor x ECP4314 / drawings = 9 lead Delta
Link
Google + Baldor x ECTM4314 etc.
Link

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[petronila]

Hi chef5mate,


If a three phase motor that drives a fixed load runs at low voltage (out of its permisible voltage limits) it will experiment drastic changes. For a fixed load the power that the motor will drawns depends of V x I, if the voltage drops, to keep the same power, the current most be increase and if exceeds the rated current, the motor will runs like in overloading condition, runs hotter and will faill (it depends of overload percent and operation time).
Another important considerations are torques (starting, pull-out and pull up) all are based on square voltage, then a reduction in apllied voltage impact in torque by squared fuction.Also with low voltages the efficiency drops and the power factor improves. Then verify the motor load to check if a 460 V motor can handle the voltage drop(this situation is that Zlatkodo is suggesting, if you can do it,feedding your actual 380 V motor with 315 V).


This would be feasible, however verify the starting method, like bill sayds the motor most be rewounded for 380 V operation and wye-delta starting. If the starting method is different the alternative could be winding reconnection (if 460 V rated connection is 1 Delta). So could be good that you ask for your dealer how are going to do that, maybe the dealer are going to send a standard new motor to one workshop for this redesign and will install a new name plate with new data. (We do the same in our workshop for some dealers that are going to provide motors to other countries). So could be good that you verify also the starting method.


If you mind is an standard, the answer is no, usually in Europe the standard is 400V-50 Hz. 380 V-60 Hz are proper of some Brazilian regions and it border of Brazil with Paraguay.

Best Regards

Carlos​

 

[rhatcher]

chef5mate,
Baldor-Reliance can supply 380V 60hz motors to your specifications. They will not be standard motors and will require special order in the same way that the original Reliance motors were ordered. Any other solution besides ordering motors to the proper voltage and frequency rating will be a compromise. For the record, other manufacturers may also be able to supply this custom rating, my point is that the proper rating should be applied.

 

[chef5mate]

Thank you all for the continuous feed of excellent information...all advices well noted...already looked up with US MOTORS and WEG, indeed all these manufacturers could supply to our specs but finally got a ring from the dealer committing to replace them with specs as per requirement (took some time to hear from this guy)...as rhatcher says "compromise" is the last thing we don't want to end up with...thanks again for the comprehensive research and sharing...