The client requests 125/216V, 3-phase panel for his work shop. The building voltage system available are 480/277V or 208/120V. We never heard this voltage system before, sounds like industrial application? How to make this happen? Is there a special xfmr to convert voltage to the requested voltage system? Thank you.
Strange voltage system
- Thread starter anbm
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- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
216Y/125 is just boosted 208Y/120
240Y/135 is another flavor which is more likely to be used.
Possibly he is looking for a compromise which can deliver higher power to 240V heaters or motors while still being (barely) within tolerance for nominal 120V loads?
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240Y/135 is another flavor which is more likely to be used.
Possibly he is looking for a compromise which can deliver higher power to 240V heaters or motors while still being (barely) within tolerance for nominal 120V loads?
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- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
He may be looking at something that says it is rated for 125V and is thinking it needs that, then is extrapolating a 3 phase voltage from that (125x1.732). Usually that is just telling you the maximum voltage something can function with, not what you would actually feed it. For example if you look on the end of a NEMA 5-15 plug, it says “125V”. Sone people look at that and think it is the voltage that a device needs.
ATSman
ATSman
- Location
- San Francisco Bay Area
- Occupation
- Electrical Engineer/ Electrical Testing & Controls
If we use the 10% nominal rule then wouldn't the 208/120V system satisfy the cust's request?
I think heaters have a much wider tolerance range but a motor, well that's another story.
I think heaters have a much wider tolerance range but a motor, well that's another story.
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
A buck/boost transformer could easily be wound to do this, but I don't think you will find it as a standard catalog item.
What you essentially need are 3 120:5V single phase transformers where the secondary is rated to be connected in series with the primary. These would be connected in the wye autotransformer configuration.
Unfortunately the standard buck/boost transformers manufactured have 12/24V our 16/32V secondaries.
I think you might be able to use 3 240:12V transformers at 120:6V to get close, but you lose half their capacity in order to use common hardware.
Jon
What you essentially need are 3 120:5V single phase transformers where the secondary is rated to be connected in series with the primary. These would be connected in the wye autotransformer configuration.
Unfortunately the standard buck/boost transformers manufactured have 12/24V our 16/32V secondaries.
I think you might be able to use 3 240:12V transformers at 120:6V to get close, but you lose half their capacity in order to use common hardware.
Jon
MD Automation
Senior Member
- Location
- Maryland
- Occupation
- Engineer
The OP states there is 480/277V on site.
One idea for this shop might be to utilize a standard 480 Delta to 208 Wye step down transformer - and if it had 5% taps on the primary, use them to make the secondary 218Y/126. That's awful close to the desired 216Y/125.
Just a thought.
Would still want to check if the 216Y/125 was really a "thing" that was needed.
One idea for this shop might be to utilize a standard 480 Delta to 208 Wye step down transformer - and if it had 5% taps on the primary, use them to make the secondary 218Y/126. That's awful close to the desired 216Y/125.
Just a thought.
Would still want to check if the 216Y/125 was really a "thing" that was needed.
Problem is many utilities run about 4% high, which would result in 500/288 voltage.
that runs your 218Y/125 upwards of 225/130 now…
Always best to check with the utility first..
SSDriver
Senior Member
- Location
- California
- Occupation
- Electrician
Did you ask what his reasoning was?
kwired
Electron manager
- Location
- NE Nebraska
You also might want to check to see what voltage looks like loaded vs unloaded. That 4% high is probably done assuming there will be some drop when loaded. Step it up while loaded just means it goes even higher when unloaded. If it is a situation that is almost always loaded to a certain level, you maybe take that into consideration before bucking/boosting for something being added.
Nope, that’s the regulator settings.
124 with 2v bandwidth Loaded and unloaded.
kwired
Electron manager
- Location
- NE Nebraska
Yes but I assume they set it high because they expect some drop when loaded, otherwise 120 is the nominal voltage.
I see 122-124 or so a lot when unloaded, but 117 or even lower when loaded, at the service equipment.
Again, no.
Most of it is simple economics. More voltage equals more power equals more revenue for the utility.
CVR is run to curb peak demands. This is a program where we lower the entire systems voltage to use less power.
The regulator accounts for loading. When the voltage gets low the regulator steps it up.
When it gets above the bandwidth the regulator lowers it.
Electrofelon had an issue with his solar some time back but in the end it was found to be a regulator issue screwing the voltage up.
kwired
Electron manager
- Location
- NE Nebraska
For straight resistance loads yes. Motors no. Much more energy is consumed by motors but they typically draw whatever energy is demanded to do the work. Lower voltage they draw more current, raise voltage they draw less current, power tends to try to remain constant as long as driven load demands the same. If anything low voltage will be more revenue for utility as it can result in more line losses when it comes to motor loads.
Lighting might be one the bigger loads out there, but has gotten more efficient over recent years, and with some the management systems automatically increase or decrease light levels depending on conditions as well.
If anything I been seeing utility companies pushing for higher efficiency and less usage where possible, if anything to lower their need to invest in the ability to supply more energy or at least to be able to put off such investments for a longer time.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
That’s a wrong assumption. Many people believe that.
Explain how low voltage will increase revenues?
The last paragraph is where CVR is important. Peak times only
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
If that's true, then, as electric meters respond to power usage, the voltage should not affect the power used for motors.
kwired
Electron manager
- Location
- NE Nebraska
Low voltage to a motor means motor draws more current to do the same work.
More current over same size conductor increases line losses, that is real power losses. If during the winter may not be much of a loss at all, will just lessen demand on the heating system. During cooling season means more heat for cooling system to have to remove, which also may have increased losses in it's supply lines if voltage is low.
If a resistance load - typically something that heats, higher voltage just means it gets the job done faster, even if just slightly faster and not very noticeable to us people. Utility still billing for watt hours, watts go up slightly, hours go down slightly work done was still the same plus or minus line loss differences.
Most cases all this is kind of negligible though for an individual user. with large users or over the entire POCO network those issues can add up, or take away whichever applies.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The current drawn by the motor will not be proportional to the mechanical load, but that is mostly the result of zero power factor magnetizing current.
The efficiency of the motor including slip and friction, and the resistance of the wiring will cause some additional losses when the motor is "idling", but except for that the efficiency losses and wiring resistance losses will increase with mechanical power demanded.
The power (at unity power factor) going to the motor will be greater than the driven mechanical load power, but still roughly proportional and not more than 10-20% more.
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