208v or 480v? Why the difference?

[Dirty Laundry]

Hi all.

I operate a commercial laundry. We have various motors running. I have a 60hp Baldor motor (runs 10 hours per day which circulates water in wastewater treatment machine.

We are wired for 208v service into the building. This 60 hp motor/pump is wired 208v, like anything else we’ve replaced motors for over the past 20 years.

My amperage draw on this wastewater machine is 90-95 amps when the machine is running at an acceptable flow.

My friend in Ohio has TWO of these 60hp Baldor motors running with his system (2x the size of mine)……… and his amperage draw is 55-60amps, when operating at acceptable flow levels.

Does that mean his cost per gallon produced in the wastewater machine is less? Does he consume less kW than I do?

What are my options?

Remaining in compliance with the EPA has caused our electric bill to skyrocket.

What would you all suggest?

Thank you

 

[Ox]

Which 4th world country doo you live - that is running 40 and 44hz?


95 x 208 = 19.76 KVA (KW)
60 x 480 = 28.8 KVA (KW)


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Think Snow Eh!
Ox

 

[Donkey Hotey]

Electric costs are going to vary by location and whatever billing scheme your utility has. As for the exact power consumption, double the volts and you consume half the amps. The thing that remains approximately the same is watts and that's what the power company bills you for.

440-480V is a way for distributing more energy through smaller wires and switches. That's the upside to it. The downside is wayyy more dangerous to work with or around. At those voltages, arc flash is a very real possibility, you have to maintain minimum distances to cabinets, etc.

208V is more friendly for safety but, is less able to supply really high horsepower numbers without exceeding the limits of the wiring and overall power supply coming into the building.

At least that's the quick answer...

 

[Donkey Hotey]

Which 4th world country doo you live - that is running 40 and 44hz?

Pumps are running on VFD drives to control the output?

 

[dalmatiangirl61]

His location info lists Massachusetts, so I'm guessing there is a vfd in the system.

DH beat me to the explanation.

 

[Dirty Laundry]

Yes, It has a VFD.

 

[rons]

Who programmed the VFD? Check the programmed parameters changed from the defaults.

 

[SomeoneSomewhere]

Who programmed the VFD? Check the programmed parameters changed from the defaults.

I'm not sure what makes you think there's something wrong with the VFD?

If the motor only needs to run at ~70% speed to achieve the required flow/pressure, running it at that speed is much more efficient than running it at 100% and using valves to restrict or bypass the output.

 

[Dirty Laundry]

I have the Tech’s information. And have a call out to them.

However, I never like to be BS’d so I tend to do my own homework.

I was curious if the VFD’s settings had an impact.

 

[candeservices]

To get apparent voltage of a 3 phase system multiply the voltage (480) x 1.732 =831 volts multiply this to the amperage to get watts. Or 208 x 1.732 = 360 volts x amps.

A 480v motor is NOT more efficient or uses less power than a 208 or 240v motor it just allows you to run smaller wire and save money on wire and conduit size.

Both motor configurations should use the same amount of power but the higher voltage saves more money on installation.

 

[Dirty Laundry]

So. Service don’t matter whatsoever? I didn’t think it would because my whole life I hadn’t ever heard of such a thing.

NOW, that be said……. Has this conversation turned into a VFD conversation?

If so, my experience is not far from zero.

 

[EmGo]

Laundry - a real electrical guy would slap me for saying this but think of it like water. You've got a 1" pipe at 100 psi or a 2" pipe at 50 psi. Same amount of water, same amount of available work, just different delivery methods. 1" pipe is cheaper than 2" pipe.

(Yes that's technically wrong, it's an EXAMPLE).

 

[Ox]

2" is 4x the volume of 1".


-----------------

Think Snow Eh!
Ox

 

[candeservices]

Reading your text again here is what I can come up with.

example:
Motor 1 is 10hp rated at 5 amps if I put 15hp of load on it it WILL push it but struggle to do the work and life span will suffer.

Motor 2 is 20hp rated at 10amps if I put 15hp of work it will pull Less than 10 amps and be the right size for the job.

Think of it as your air compressor with a 6" pulley, if you put a 9" pulley the electric motor will draw more power to run, electric motors don't care what load you put on the they Will try to run.

In Conclusion there might be more head pressure on your system or some kind of restriction. Maybe one winding in your motor is starting to go bad. Hell I don't even know if elevation has some thing to do about it. Look at the name plate on your motor and it should tell you what amperage it draws at what voltage when properly loaded down it should read this or slightly lower.

 

[candeservices]

2" is 4x the volume of 1".


-----------------

Think Snow Eh!
Ox

It is also 4x the cost to install it, but if you don't need the additional flow Why pick the bigger size?

 

[EmGo]

2" is 4x the volume of 1".

How did I know that someone would jump on this ?

Mea culpa, mea maxima culpa. As penance, some snow for Ox



happy new year and ally ally oxen free

 

[Sam L]

The cost savings in a high voltage system also comes from amperage draw.
If you have 3 phase power, on your electric bill you will have a "Demand Charge".
This charge consists of taking the highest amp draw for a given time and then multiplying it with the usage for the month.
The demand charge is usually a significant part of the electric bill (Summer demand is even worse).
So if you have higher voltage, you will have lower amp draw, which in turn gives you lower demand cost.
The only way you might be able to reduce your amperage draw is to extend the time that the motor takes to get up to speed. The VFD may have a setting for that.

Good luck
Sam

 

[Ox]

I think you missed one part of that demand equazsion.


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Think Snow Eh!
Ox

 

[mksj]

Demand: The maximum rate of power used in a 15-minute interval during a single billing cycle. Demand can be shown as kW or kVA on your bill and is used by your power company to calculate your demand charges.

It is not that you are using twice the amps at a lower voltage, and it is usually measured over a 15 minute interval for on-demand charges. Given the nature of the VFD and that this is a fluid system, I would not expect high current start up. There may be a higher efficiency factor using a higher voltage. One would assume the the VFD was built as a system in this scenario, that the VFD is programmed and tuned to the motor system. A small decrease in flow may have a significant factor in power consumption, similar to swimming pool variable speed pumps, a decrease of 100-200 RPM pump speed and running it a bit longer has a significant effect on both the on-demand as well as overall energy consumption. So possibly some tuning of the system may improve your power consumption.

 

[SomeoneSomewhere]

The cost savings in a high voltage system also comes from amperage draw.
If you have 3 phase power, on your electric bill you will have a "Demand Charge".
This charge consists of taking the highest amp draw for a given time and then multiplying it with the usage for the month.
The demand charge is usually a significant part of the electric bill (Summer demand is even worse).
So if you have higher voltage, you will have lower amp draw, which in turn gives you lower demand cost.
The only way you might be able to reduce your amperage draw is to extend the time that the motor takes to get up to speed. The VFD may have a setting for that.

Good luck
Sam

Maximum demand is usually charged in kVA, so is also independent of voltage.