I want to step 240 single phase to 480 volt 3 phase. I understand I can wire a transformer in reverse to achieve this. Can the transformer convert to 3 phase power or do I need a phase converter on secondary? I need a neutral so transformer will be a wye and not sure what kva I'll need yet. I deal with mostly residential and don't have alot of experience with transformers. Any good websites referencing transformers? Thanks
240 volt to 480 volt transformer
- Thread starter Ken 6789
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- Wisconsin
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- PE (Retired) - Power Systems
If you need 480Y/277, you will need to purchase a step-up transformer, running a step-down unit in reverse will not provide you with the neutral connection.
If you need 3-phase from single-phase you will need some typ of phase convertor.
stevebea
Senior Member
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- Southeastern PA
You can check out Federal Pacific and Hammond website. They both have info on transformer basics. Hope this helps.
BILLY101
Member
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- Telford, Pa
1 phase transformers are available to step up voltage from 240 to 277 volts.
Sola/Heavy duty HS12F series for example.
If 480 v, 3 phase is required for motors an inverter will be needed.
The question does not indicate what 480/277 is being used for.
If 277 volt is the only voltage needed, usually lighting, then an inverter is not needed.
Simple use a 1 phase transformer to step up the voltage to 277.
BILLY
Sola/Heavy duty HS12F series for example.
If 480 v, 3 phase is required for motors an inverter will be needed.
The question does not indicate what 480/277 is being used for.
If 277 volt is the only voltage needed, usually lighting, then an inverter is not needed.
Simple use a 1 phase transformer to step up the voltage to 277.
BILLY
controlled
Senior Member
- Location
- Bowmanville, Canada
I have use Rotary Phase Convertors from Rotadyne many times with good luck.
http://www.willett.ca/RotaDyne.htm
Derek
http://www.willett.ca/RotaDyne.htm
Derek
LarryFine
Master Electrician Electric Contractor Richmond VA
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- Henrico County, VA
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- Electrical Contractor
Ken, tell us more about the loads; not just size, but types and quantities.
Keep in mind that you'll need more kva at 240v than you'll get at 480v.
Keep in mind that you'll need more kva at 240v than you'll get at 480v.
Neighbor of mine is considering purchasing the Nissan Leaf, all electric car. There are 3 options for charging: 120 volt, 20 hours to charge; 240 volt, 7 hours to charge; 480 volt, 30 min charge @80%. He wants to see if 480 volt power is possible in his garage, which I told him no house has 480 service and step-up transformer is required and not cost-effective. I tried to convince him to wire at 240 volt, but he wants to recharge car in shortest time possible. Also, I told him the expense and a higher electric bill, but still insists on shortest recharge time. I am not 100% sure if charger is 3 phase yet or amperage requirements. I know at 240 single phase, the spec calls for 40 amp ocp. Thanks for replies.
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curt swartz
Electrical Contractor - San Jose, CA
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- San Jose, CA
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- Electrical Contractor
From what I have read there are very few 480 volt chargers currently produced and they cost about $40,000. I believe they require a 125 amp 3 phase circuit. These chargers are designed for commercial applications not residential.
kwired
Electron manager
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- NE Nebraska
Dont you mean - You will need more amps at 240 to get the same Kva at 480.
The first thing you really need to know is what VA is needed. You may be able to charge it faster @480 volts but what if after transforming voltage and possibly going through phase conversion you need about 80 amps @ 240 volts single phase and his house only has a 100 amp panel? (The 480 volt 3 phase would draw about 23 amps per phase in this case)
Electric bill will not be any higher - it will take the same kWhrs to charge the battery to the same level (ignoring losses which should be minimal) no matter what the source is. You pay for Kwhrs not amps.
broadgage
Senior Member
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- London, England
Apart from the cost of the 480 volt charger, and the cost of the transformer and phase converter, it is most unlikely that a domestic service will have sufficient capacity.
It is stated that the 240 volt charger requires a 40 amp circuit and charges in 7 hours.
The 480 volt charger is said to take only 30 minutes, one fourteenith of the time, therefore it must require about 14 times the input current or about a 560 amp circuit at 240 volts.
This is only approximate, but suggests that it cant be installed in a home without either a 480 volt 3 phase service, or a most improbably sized lower voltage service, such as 500 or 600 amps at 3 phase 120/208.
It is stated that the 240 volt charger requires a 40 amp circuit and charges in 7 hours.
The 480 volt charger is said to take only 30 minutes, one fourteenith of the time, therefore it must require about 14 times the input current or about a 560 amp circuit at 240 volts.
This is only approximate, but suggests that it cant be installed in a home without either a 480 volt 3 phase service, or a most improbably sized lower voltage service, such as 500 or 600 amps at 3 phase 120/208.
kwired
Electron manager
- Location
- NE Nebraska
That would require a 433 amp circuit @ 240 volt single phase.
Not only will he spend $40K for the charger he would need new service, if he can't get 3 phase service then conversion equipment, possible construction fees from POCO on top of fees from the EC - most will not build a service like this if the return on investment is long term. The load is around the 100kW range but for only half hour or less (assuming the half hour is for a fully discharged battery). This is a high draw for residential services but for an equivelant commercial/industrial service it is not really that much load for the more expensive equipment needed to deliver it. Connecting it could cost another $40K or more. What is the price of the car.
It still takes natural gas, coal, nuclear, etc. to generate the power for this car in most cases.
- Location
- San Francisco Bay Area, CA, USA
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- Electrical Engineer
Reading some blogs and forums on this subject (I am considering one), it appears the 480V charger is not yet available, but may require 50kW at 480V 3 phase. Given that it will be a rectifier and most likely a PWM design, it will be a non-linear load, meaning lots of harmonics so low power factor. You would need more kVA to supply it safely, therefore I would say a 75kVA 240-480 K-4 rated 3 phase transformer at least. Then you must consider the efficiency loss through the phase converter, assume at least another 20%. So yes, it's only going to need a 45A 240V 1 phase service (using 208A 3 phase current at 240V to a 75kVA 3 phase xfmr, 3 phase conversion factor and 20% additional for converter).
It also appears that so far, the only 3 phase quick charger available is the one developed by Nissan for Japan;
So maybe you can get away with not having to step it up to 480V, and let's ASS-U-Me for the moment that this charger has enough tolerance to accept 240V 3 phase instead of 200V (+20% would be unusual though). It's still going to need roughly a 200A 240V 1 phase circuit to feed it. So as mentioned, new service, PoCo charges etc.
Bottom line, totally impractical IMHO.
It also appears that so far, the only 3 phase quick charger available is the one developed by Nissan for Japan;
So maybe you can get away with not having to step it up to 480V, and let's ASS-U-Me for the moment that this charger has enough tolerance to accept 240V 3 phase instead of 200V (+20% would be unusual though). It's still going to need roughly a 200A 240V 1 phase circuit to feed it. So as mentioned, new service, PoCo charges etc.
Bottom line, totally impractical IMHO.
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