Any advantage to higher voltage motors?

[Ron74]

Hi,

I am trying to figure out what type of motor should I use for the equipment for the pilot I design.
Is there any advantage to 575V 3p motor over 440V 3p? I am talking mostly about low output motors, up to 10kW.
Will there be any advantage for 150kW equipment?

Thanks,
Ron

 

[waross]

The most advantageous will be to use a motor that matches the available voltage.
In the US you may not find many 600 Volts supplies (for 575 Volt motors), while in Canada 600 Volts is a standard voltage.
There are still a lot of 480 Volt systems in Canada but for many years the utility standard has been 600 Volts. Some plants use 480 Volts but source it with their own transformers.
Some Canadian plants have dedicated 480 Volt systems for heat tracing only, not available for motors.
You won't easily find any 440 Volt, 60 Hz motors. The standard motor voltage is 460 Volts (for use on 480 volt systems).
For Canada, 575 Volt motors.
For the US and some Canadian plants, 460 Volt motors.

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

 

[Ron74]

Thank you, since I need a DC power supply, that I could only find at 480V, I figured I will have to buy a transformer anyhow, so I might as well expand the available motors that I can use.

 

[waross]

If you use an open delta autotransformer you will be able to input either 480 Volts or 600 Volts (through different input connections) and be able to run either 480 Volt or 600 Volt equipment. (460 Volt or 575 Volt motors)
There are other solutions but in many instances the open delta autotransformer is the cheapest.

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

 

[HamburgerHelper]

You can get more torque by increase the current or the amp turns. Higher voltage let you use thinner wire which you can use to create more turns when you wire the motor.

Higher voltages usually means the connection. To the grid is stronger.

Lower losses due to needing to draw less current to get the same torque.

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If you can't explain it to a six year old, you don't understand it yourself.

 

[waross]

If you give us a little more information we can give better answers. Is your market local, US, Canadian, US and Canadian, world wide?
What is the HP or current draw of the components that you will use?
For 150 KW, match the available voltage.

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

 

[edison123]

HH - All your points are incorrect.

OP - At that 10 KW range, any low voltage will work. Your only criteria is what is the readily available voltage at your location.

Muthu

http://www.edison.co.in

 

[itsmoked]

The general point to higher voltage motors is that you can wire them with smaller less expensive wire that is rated for half of what the lower voltage motor current would need. Copper wire is no longer cheap.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

The counter-argument is that at higher voltages on relatively small machines you can end up filling a large percentage of the available core slot area with inactive insulation material, where at lower voltage you can get higher percentage fill with active current-carrying (i.e. torque-producing) conductor.

 

[itsmoked]

But Scotty how does that matter since 90% of motors are dual voltage?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[edison123]

For random wound LV motors, the winding insulation is practically almost the same from 200 to 600 V and so the copper fill factor is almost the same over this voltage range. The insulation starts to affect the slot fill factor (and hence the frame derating) from 3 KV onward for form wound coils.

Muthu

http://www.edison.co.in

 

[Ron74]

Well, this is confusing...
So if I understand correctly, there shouldn't be any difference for small motors?
The autotransformer seems like a great option for us, I will check it out.
I was thinking of buying those AC to DC converters

https://magna-power.com/products/magnadc/ms,

several of those will give me the output I need, but they do not have any 600V option.

Ron

 

[HamburgerHelper]

Edison,

Tell me why what I said was not true for motors as they increase in voltage?

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If you can't explain it to a six year old, you don't understand it yourself.

 

[waross]

Any advantage to higher voltage motors?

The rule of thumb is when the motor Horse Power is higher than the voltage it is time to run the numbers on a higher voltage motor.
If your motors are less than about 500 HP each, don't worry about high voltage.
Also, in this instance when we talk about higher voltages we are talking about moving up from 480/600 Volts to 4160 Volts or more.
If you are comparing motors in the lab, you can quantify the slight possible difference between a 460 Volt motor and a 575 Volt motor but you are not doing a laboratory analysis. You, as I understand it, are selecting a motor to purchase.
MATCH THE MOTOR TO THE AVAILABLE VOLTAGE.
As an example; If you select a 575 Volt motor because of greater efficiency over a 460 Volt motor, you will need a transformer which will erase any savings in initial motor cost and running efficiency many times over.
The perceived advantage of a 600 Volt motor over a 460 Volt motor is a fine point.
The added losses of a transformer to run a 575 Volt motor with a 480 Volt supply is a GROSS point.
You mention a DC power supply and a 150 kW load as well as motors below 10 kW.
You may have unasked and unanswered questions in addition to motor voltage.
What are you designing/building?

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

 

[waross]

Ron74; Lest the voltages that I quote are confusing:
In North America standard SUPPLY voltages are multiples of 120 Volts;
120 V, 240 V, 480 V, and in Canada, 600 V.
In North America standard MOTOR voltages are multiples of 115 Volts;
115V, 230 V, 460 V, and in Canada, 575 V.


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

 

[Ron74]

As I said, I am in Canada and have a 600V supply to the plant.
I cannot find any 600V AC to DC converter so I will have to use a transformer. And this is a large part of the production costs, so I so should I invest more time on finding one or asking for a custom design?
I've read in another post somewhere that 575V motors are not common in industrial applications here, most of my experience is with the European voltage. 600V is used mostly for commercial application and municipal wastewater, I do not know if this true.
I will get on a later stage an electrical engineer to design, but I need to order the motors before.

 

[HamburgerHelper]

Warross,

Is that rule of thumb for certain voltage ranges? For a 480hp motor being fed by 480, I am getting near 600A and that would require 1000 mcm cable if you didn't bundle.

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If you can't explain it to a six year old, you don't understand it yourself.

 

[waross]

If the utility is supplying the transformer in Canada it will most likely be 600 Volts.
Smaller plants generally use the 600 Volts supplied by the utility.
Larger plant who typically buy their own transformer must decide what voltage to use.
I have worked in plants that were 600 Volts, plants that were 480 Volts, plants that were 600 Volts but also used 480 volts for specific equipment, and one plant that had about a 50/50 mix of 460 and 575 Volt motors and had both 600 and 480 Volts.
600 Volts is the standard.
480 Volts has a much greater range of available equipment from the US.
You should be asking us how to source your DC supply.
You should be finding out the supply voltage where your equipment will be used.

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

 

[waross]

HH; Good question. If you are moved to ask that question, then it is time to consider going to 2400 V, 4160 V or higher.
Consider the cost of supplying 4160 Volts, transformer, switchgear.
Consider the training and abilities of the electricians who will be responsible for the motor. You may have to contract an outside contractor who has higher voltage experience.
I remember one installation with a 120:208 Volts supply and a second 4160 Volt supply for one 600 HP A/C motor.
I have seen more than one installation of 3000 HP motors where the supply was 13,000 Volt class.
It could have been 4160 Volts, but given the number of motors involved and other factors, they designers chose 13,000 Volts.
One plant was a total of 36,000 HP (12 x 3000 HP) at 13,000 Volts.
One was a total of 48,000 HP (16 x 3000 HP) at 13,000 Volts.
The rule does not mean that when the HP exceeds the voltage you must go to a higher voltage.
The rule means that when the HP exceeds the voltage it is time to run the numbers. (even at 208 Volts)

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

 

[itsmoked]

Ron74; What do you need for DC? Volts? Current?

Keith Cress
kcress -

http://www.flaminsystems.com