Natfuelbilll
Senior Member
Customer has 280A of load 5400' from electric utility. What is best source for step up/step down transformers and equipment?
Single phase power extension
- Thread starter Natfuelbilll
- Start date
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zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Having the ulitity extend the service?
Volta
Senior Member
- Location
- Columbus, Ohio
What voltage is the load?
- Location
- Massachusetts
Will the utility supply at a medium voltage and then you run the 5400' to a customer owned transformer?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
The power company would be my first choice. (Doing, not supplying.)
What were they planning to do for power when they chose the site?
Way too little information here to give any meaningful answers..but as stated, let the POCO deal with it.
HV/MV services are a specialized art form and can be extremely dangerous if poorly designed /installed.
What is the utilization voltage of that 280 amp load? Overhead or underground?
There are some options on transformer, with common arrangements being customer-owned, POCO maintained, POCO owned, POCO maintained (most likely setup with the load you specified), and customer-owned, customer maintained.
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Natfuelbilll
Senior Member
Sorry for the delay. The load is 120/240 v single phase.
My source is 240v single phase. The power co will not extend their line.
I need to take a 120/240 single phase service. Step it up. Transmit it. Step it down.
My source is 240v single phase. The power co will not extend their line.
I need to take a 120/240 single phase service. Step it up. Transmit it. Step it down.
broadgage
Senior Member
- Location
- London, England
This is going to be very expensive.
70 KVA transformer to step up from 240 volts to say 4KV
5,400 feet of MV cable.
70 KVA transformer to step down from 4KV to 120/240.
Remember that the load will probably be much less most of the time, but that the customer will be paying for the iron losses in 2 transformers 24/7, forever.
Such loses vary according to transformer design, but might be 1.5% in each transformer. That is a continueing loss of about 2KW, or at $0.15 a kwh a cost of over $2,600 a year.
Copper losses would vary according to load, but could be as much again.
Also the voltage at the load will vary a lot, and may be unacceptable.
The voltage of the 240 volt supply might well drop 5% under load, and another 2% drop could occur in each transformer, with say another 3% in the MV cable and in the relatively short 240 volt connections to the transformers.
The total change in voltage from full load to very low load could easily be 12%.
If one designed for 125/250 volts at low load, that would drop to about 110/220 volts at full load, and even less at appliances due to voltage drop in feeders and branch circuits.
If the POCO can not be induced to extend the MV service to nearer the load, then it might be worth useing a generator. (and possibly a battery bank and inverter at times of low load.)
70 KVA transformer to step up from 240 volts to say 4KV
5,400 feet of MV cable.
70 KVA transformer to step down from 4KV to 120/240.
Remember that the load will probably be much less most of the time, but that the customer will be paying for the iron losses in 2 transformers 24/7, forever.
Such loses vary according to transformer design, but might be 1.5% in each transformer. That is a continueing loss of about 2KW, or at $0.15 a kwh a cost of over $2,600 a year.
Copper losses would vary according to load, but could be as much again.
Also the voltage at the load will vary a lot, and may be unacceptable.
The voltage of the 240 volt supply might well drop 5% under load, and another 2% drop could occur in each transformer, with say another 3% in the MV cable and in the relatively short 240 volt connections to the transformers.
The total change in voltage from full load to very low load could easily be 12%.
If one designed for 125/250 volts at low load, that would drop to about 110/220 volts at full load, and even less at appliances due to voltage drop in feeders and branch circuits.
If the POCO can not be induced to extend the MV service to nearer the load, then it might be worth useing a generator. (and possibly a battery bank and inverter at times of low load.)
I'm certainly not advocating it, but if you step up to 600 volts, and my VD calculator worked, with 750 kcmil AL you would have a little less than 6% VD at full load and you might be able to compensate with taps on the load side transformer.
Natfuelbilll
Senior Member
Expensive for one person is a bargain for another.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Which can result in over-voltage when lightly loaded.
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
Can the load be divided up into portions that are relatively insensitive to voltage drop and portions that require stable voltage?
Is this a residential application (where a 200A service might be very common, but normal usage averages well below the service rating)?
Would an off grid solution be cheaper than creating a grid connection?
-Jon
Is this a residential application (where a 200A service might be very common, but normal usage averages well below the service rating)?
Would an off grid solution be cheaper than creating a grid connection?
-Jon
If money is not an object, you can run (8) sets of 750mcm cable or use combination of step up transformer + (x) sets of cable in paralel + buck transformer
Really? Who is the POCO? I believe they have a mandate to provide service to customers whenever possible, even if it isn't easy to do so. You need to talk to someone else in that POCO, and if that doesn't work a call to the Public Utilities Commission may suddenly motivate that POCO.
My former boss built property in Oregon, and the POCO gladly extended their lines and set a transformer..at his expense. But it was still far cheaper than the solution of step up/MV cable/step down.
He was required to deed and maintain an easement for access to maintain the line and transformer.
However, all bets are off IF the 240 volt service you speak of is already located on the customer's property. In that case the POCO is indeed no longer obligated to extend the service, BUT it may be cheaper to pay them to do it, if they will.
I agree with augie47, that a 600 volt transformation would be most cost-effective, no need to go up to 4kv level for this.
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