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Old January 11th, 2019, 05:43 AM   #16
Gene Bond
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240/480 50/60 HZ is odd. You have a factor 2 ratio between what I interpret as delta and star connection, not the usual factor 1.732.
Is it to be interpreted as that at 50 Hz, the motor should be connected to 240V delta, and at 60 Hz the motor should be connected at 480V star ?
Typically, NEMA motors are series or parallel connected for 480 or 240.

If the performance required of the pumps is adequate at 50hz, then you should be fine. If 60hz is required, then you're in trouble at 400v input to the vfd.
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Old January 11th, 2019, 06:49 AM   #17
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It does not make any sense to me.
He has 400V supply available despite it is not a standard voltage in the US.
He then wants to connect a motor that is rated for the standard voltage 480V.
Why have a speciel 400V supply when the devices that are to be connected are rated for the standard 480V ??

he wrote "COPY EXACT PHILOSOPHY" of the Singapore plant. Was that interpreted as that he absolutely have to use 400V ?

And what about the 50/60Hz ? Is this an issue or a non-issue for the process ? Is this the reason why he wants to add a VFD ?
To copy the "philosophy" sounds not to me that everything must be exactly the same. It could be interpreted that you could adapt the hardware to achieve the same thing. Like changing a pump from x liters/h @ 50 Hz to a pump that provides the same x liter/h @ 60 Hz. Or changing the gearing on a conveyor. Or just changing V-belt pulleys. Having to add a VFD could be a solution if nothing simpler can achieve the same thing.

IMO it is not possible to answer any questions before all the information is out. That includes a photo of the name plate.
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Old January 11th, 2019, 09:50 AM   #18
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Originally Posted by skyfox View Post
Happy new year everyone.

This is more of a Electrical engineering question than a PLC one.

Can a Motor and a VFD that is rated for 240/480 60/50Hz operation be used on a system that has utility supply power of 3-Phase 400VAC? Customer is dictating 400VAC transformers for both their US and overseas factories? However, control cabinet electronics being used for powering the PLC, 24VDC Power Supplies etc., are running off from a 120 V step down from this very same 400 VAC transformer.

Can this be done or do I need to look for a VFD and a motor that is rated strictly for 400VAC use?

Thanks.
So for instance with us we use a lot of SEW eurodrive VFD's and their input voltage is usually a range "3x380-500V" @ "50-60hz". With a drive like this, you shouldn't have any issue supplying 400vac and controlling a motor rated for 480vac. I know that on some drives(Siemens), you will need to tell it what voltage it will be supplied, but most of these(SEW) that's not the case. If you exceeded the rating you would generate an overvoltage bus fault, and I expect the same would happen if you were under.

Seems odd they would specify 400vac unless the majority of the equipment will be in service outside the US, which may very well be the case.

Last edited by dwoodlock; January 11th, 2019 at 09:53 AM.
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Old January 11th, 2019, 08:11 PM   #19
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Originally Posted by Aabeck View Post
I work on quire a few machines from Italy, Germany and China - where 400V is the norm.


These machines need a 480 - 400 3 transformer for their power. A 480V VFD fed 400V will fault for buss undervoltage. Frequently they are built without a control voltage transformer - 400V usually has a neutral that gives 200V and a DC power supply input is rated up to 250V. Rarely is there anything in the panel that is 120V.


Short answer = No. Tell the customer they need a transformer.
I seem to recall being told (yea I know it is vague) of a machine not running on 480 properly. The machine was shipped with a ~460 to 400V transformer and never ran properly until it was hooked up. This machine likely did have a servo drive, but not VFD per say. If you are being told the machine needs a 4xxV to 400V transformer, put it on one. I was assuming it was an entire machine and not just a motor.
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Old January 12th, 2019, 05:35 AM   #20
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Quote:
Originally Posted by skyfox View Post
Happy new year everyone.

This is more of a Electrical engineering question than a PLC one.

Can a Motor and a VFD that is rated for 240/480 60/50Hz operation be used on a system that has utility supply power of 3-Phase 400VAC? Customer is dictating 400VAC transformers for both their US and overseas factories? However, control cabinet electronics being used for powering the PLC, 24VDC Power Supplies etc., are running off from a 120 V step down from this very same 400 VAC transformer.

Can this be done or do I need to look for a VFD and a motor that is rated strictly for 400VAC use?

Thanks.
A 480V 60Hz motor will work quite well with 400V 50 Hz because the lower voltage is compensated by the impedance reduction due to the lower frequency.

In contrast for the VFD you need one for 400V. It will not be difficult to find one since the most of the world works with 400V 50Hz, except in the US and its area of influence.
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Old January 12th, 2019, 05:49 AM   #21
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The specs plate of a standard three-phase induction motor. Note that the motor gives less power at 50Hz than at 60Hz and if it is going to be used at 50Hz you may have to select a slightly larger motor apart from calculating the gearbox for the 50Hz speed.
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Old January 22nd, 2019, 06:42 PM   #22
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Originally Posted by JesperMP View Post
It does not make any sense to me.
He has 400V supply available despite it is not a standard voltage in the US.
He then wants to connect a motor that is rated for the standard voltage 480V.
Why have a speciel 400V supply when the devices that are to be connected are rated for the standard 480V ??

he wrote "COPY EXACT PHILOSOPHY" of the Singapore plant. Was that interpreted as that he absolutely have to use 400V ?

And what about the 50/60Hz ? Is this an issue or a non-issue for the process ? Is this the reason why he wants to add a VFD ?
To copy the "philosophy" sounds not to me that everything must be exactly the same. It could be interpreted that you could adapt the hardware to achieve the same thing. Like changing a pump from x liters/h @ 50 Hz to a pump that provides the same x liter/h @ 60 Hz. Or changing the gearing on a conveyor. Or just changing V-belt pulleys. Having to add a VFD could be a solution if nothing simpler can achieve the same thing.

IMO it is not possible to answer any questions before all the information is out. That includes a photo of the name plate.



JesperMP,


I know it is a bit confusing but let me try and explain again.


Singapore Plant: 400VAC 3Phase 50Hz


US Plant: 400VAC 3Phase 60Hz

New Information I have on the Pump Motor:



(Still no Pics of the Pump Motor Label)

230/400V D/Y 3.0 l/min. At 50Hz.

VFD Operation:

7.5 kW / 230V 3,000 RPM at 50hz. (Delta Connection)
15.0kW / 460V 6,000 RPM at 100Hz (Delta Connection)

I am being told that this was run a using the 15kW configuration on 400VAC @ 50Hz. I am a bit confused as to how the VFD was able to output 460V (provided they ran at max RPM), when incoming power to it was at 400VAC (50Hz Line frequency). Reason for the VFD is them wanting to control the Pump Flowrate.


My question is, what do I need to do to achieve the same performance at the 15kW power configuration using 400VAC Power at 60Hz (instead of at 50Hz) without increasing the speed of the motor by 20%? Do I limit the max frequency output of the VFD? Any other VFD programming parameters i need to be concerned with?
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Old January 23rd, 2019, 03:25 AM   #23
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Very doubtful that the pump/motor has run at 460V 100 Hz. I wouldnt take it at face value.
Motor is rated for 400V, then do not run it at 460V.
Pump is for 50 Hz, if running it at 100 Hz is a huge difference. If it is a centrifugal pump, its load on the motor would in principle quadruble.

The 460V does not match neither motor nor VFD. I dont think it is a correct statement.
In is most likely that the motor was connected in Y, and the VFD output 400V 50Hz.
Then everything matches up.
If that is the case, you dont have to change anything since the pump then runs at its designed speed.
To be sure, get a photo of the name plate(s) of pump and motor.
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Old January 23rd, 2019, 03:55 AM   #24
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This is not an electrical problem. It is mechanical.
Quote:
Originally Posted by skyfox View Post
Reason for the VFD is them wanting to control the Pump Flowrate.
If they want to adjust the flowrate between 0 - 3 liter/min, then you can do so easily. Down to 0 is probably OK, since the pump load will be zero.

If they want to adjust the flow above 3 liter/min, then probably a little bit higher than 3 liter/min will be fine, but that is just a guess.

Significantly more than 3 liter/min, then maybe it is possible, but you have to analyse the pump application in detail.
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Old January 25th, 2019, 02:48 AM   #25
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At 460V supply...you could set max voltage out of the VFD at 400V, 50Hz.

I have even done this on a 240V motor with both 400V and 460V supply to VFD.
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Old January 25th, 2019, 03:07 AM   #26
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He has 400V supply.
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Old January 25th, 2019, 07:40 AM   #27
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Maybe you can just rewire the motor connections to the lower voltage?
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Old January 25th, 2019, 07:56 AM   #28
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He has a 400V supply and a 50 Hz pump rated for 400V in Y.
He says the pump has run @ 100 Hz and 460V. It makes no sense.
I think he should come back with better information.

Threads like this aggrevates me to no end.
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Old January 25th, 2019, 12:14 PM   #29
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Someone is getting confused with the voltages used in the US but not in most of the rest of the world where 400V is used, not 460 or 480.

If an installation is made for Singapore or Europe then the VFDs, motors, etc. they must be chosen and calculated for 400V 50Hz and it has to completely forget about higher voltages.

And pay attention to that pump that is intended to work at twice the nominal speed. Most pumps in those conditions tend to malfunction, the power is multiplied by 4, they usually have a very low performance, they probably heat the fluid a lot and even they can have cavitation problems. It would be much safer to choose a pump that directly gives the high flow with the nominal frequency of 50Hz, then there will not be any problem to work at lower frequencies
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Old January 25th, 2019, 01:53 PM   #30
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I see this occasionally around here, albeit not as much lately. His end customer is likely a Fab for the Semiconductor industry. Internally, most motors used in the machines are servos or on VFDs, so the incoming frequency is irrelevant since they are using power supplies for almost everything (except heating). So to maintain consistency around the world, the Fab owners in North America get custom 480-400V service transformers at the site. That way they use all identical equipment wherever they go. "Copy Exactly" is a term used by Intel for ALL equipment going into any of their facilities, meaning if you supply a piece of equipment to them in one place and they order another one, it must be EXACTLY the same in EVERY detail, right down to the plating of screws (that is an example they use in their training). So as nuts as this sounds, it is the way it is done in that industry.


So back to your problem;
No, you cannot operate a motor that is designed for 480V 60Hz by giving it 400V 60Hz. The motor will still attempt to spin at the same speed (based on getting 60Hz), but the ratio of Volts and Hz is incorrect and the motor will not develop rated torque. Torque varies at the square of the voltage difference, so 400V is 83% of the motor rating, therefore the torque will only be 69% of what the motor is rated for. SOMETIMES an equipment designer will have a "fudge factor" in the motor selection, but not so much any more, and I have never seen more than 20%. So no matter what, your motor will not develop enough torque, which means it will have higher slip, draw more current while doing less work, and either trip the Overload protection or burn up.


When you have a VFD on that motor, you can limit the speed to 83% of rated, which would make the motor see the correct V/Hz ratio and develop rated torque, albeit at the reduced speed. In something like a centrifugal pump that means less flow and may affect the head capability, so it needs careful consideration.


From your last post though, it appears as though the motor is NOT rated for 480V, it is rated for 400V. That's fine, you are good to go. The VFD will just be programmed to put out 50Hz at 400V as per the motor specs and you get full torque and rated flow. It's unlikely that it was ever putting out 480V from the 400V supply, that would not have made sense. That was likely just someone ASSuming something that they didn't understand.
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