Cost for a primary line

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gar

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Location
Ann Arbor, Michigan
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EE
180107-2202 EST

What might be a ball park cost to obtain 3 phase power at a 1 phase location where an additional 1 line might have to be run 1/2 mile, and transformers for an open delta of about 200 kVA. More likely about 100 kVA of transformers would be needed for inrush, not steady state. I don't know the size of the existing single phase transformer. Might only require the wild leg transformer.

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peter d

peter d

Senior Member
Location
New England
We recently did a 1,200 amp condo service, 120/208 volts. The owner had to pay $25,000 for the cost of the 150 kva padmount and extending the 3-phase high voltage about 400 feet. Two new poles had to be installed.
 
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JFletcher

Senior Member
Location
Williamsburg, VA
This will vary quite a bit by state/PoCo. Had a friend who needed a household service, nearest electrical was a bit over a mile away. Cost for the poles and stepdown xfmr was ~ a quarter mil. NV.

He is on solar.
 
mivey

mivey

Senior Member
JFletcher said:
This will vary quite a bit by state/PoCo. Had a friend who needed a household service, nearest electrical was a bit over a mile away. Cost for the poles and stepdown xfmr was ~ a quarter mil. NV.

He is on solar.
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That's pricy. I would expect around 1/2 that for the line. Did they have a lot of right-of-way to clear?
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
IIRC, national grid here in central NY charges $15 foot for underground primary single phase - you dig, provide sand, and backfill. $25 foot for OH single phase primary extensions. Not sure how much less, if any, adding a third conductor to existing poles would be, but those numbers roughly match Mivey's.
 
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gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
180108-0641 EST

A little more detail. And thanks for the replies.

My son is looking at a country home that is on about 15 acres on a moderately main road that in addition to the home has a large horse barn and a smaller barn. The property cost is about a wash with his present home. The home would take some money to upgrade.

His shop in the city currently is about 7000 square feet with three different meters. The barns would provide more space. The CNCs and other machining machines run on a 240 V 200 A open delta supply. Air compressors and welding equipment are on other meters. Welding is single phase. Air compressors are 3 phase.

Obviously a lot of money has to go into the barns to make shop space.

The present single phase power to this property is overhead and I doubt that any change would be required here. I believe the point where 3 phase ends is probably delta with no neutral. Line of sight to where 3 phase is is much closer than 1/2 mile, but would require poles and wire.

We sort of judge that a 100 HP rotary phase converter could could supply the existing needs. These are about $6000. Then there are really a number of existing rotary converters that automatically exist on the various machines by virtue of there being 3 phase motors on the machines. Quite obviously all single phase loads would directly come from the single phase source and thus would not load a rotary converter.

Air conditioning would be single phase.

We know of one case where a $30,000,000 home wanted 3 phase power, but DTE wanted a prohibitive amount to provide it so they went with an 800 A single phase service. I don't know the distance to 3 phase power in that location.

In all older neighborhoods around here we have 3 phase on the pole. If I wanted 3 phase in my home it would only be the cost of a transformer, and possibly not that because I don't know the public service rules.

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Iron_Ben

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Location
Lancaster, PA
gar said:
180107-2202 EST

What might be a ball park cost to obtain 3 phase power at a 1 phase location where an additional 1 line might have to be run 1/2 mile, and transformers for an open delta of about 200 kVA. More likely about 100 kVA of transformers would be needed for inrush, not steady state. I don't know the size of the existing single phase transformer. Might only require the wild leg transformer.

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Obviously a lot of variables here. How much “new” load the utility expects to see is a significant economic consideration. It sounds like the answer in this case is none, as the load is merely relocating. (I’m assuming it’s the same utility.) Any number I throw out is an educated WAG of course. Something in the neighborhood of $25k is what I’ll go with.
 
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gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
180108-1155 EST

Iron_Ben:

Thanks:

We have now found a document on DTE rate structure, and we don't really know how to read it yet.

Single phase extension seems to be about $6.5/ft for overhead. If DTE wants to go underground, then the additional is their cost. The cost per foot is the shortest distance to the source even if DTE wants to use some other route.

There was nothing about adding a wire to get 3 phase.

The customer has to foot the upfront cost. But it appears that over a 5 year period your electrical usage is used to paydown some or all of this cost.

Transformer cost seems reasonable.

My son's present cost is about $600/month at $016 that is 3750 kWH/month. Using 30 days and 8 hours that is an average load of 15.6 kW. I doubt that short time peak would be 10 times this.

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gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
180109-1525 EST

My son has now had an informal discussion with DTE and the ballpark would be $30,000 to $60,000. All new poles and lines would be required based on Michigan rules. Any customer requesting a new service has to pay the full cost (none of it can be spread to other customers). When counties require permits it is $1000 per permit.

A 100 HP rotary phase converter is in the $7000 range, and a 60 HP a good fraction of the 100 HP, but two 60 HP units could still be a good direction. Redundancy is one reason, and lower losses at lighter loads is another. A high inertia load on the converter could be useful for short power dips. Clearly rotary converters are the way to go. One does not very often need full power capability and thus smaller units paralleled make more sense.

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Brad45

Brad45

Member
Location
Midland, TX, USA
Depends on nearest 3 Phase site

Depends on nearest 3 Phase site

At my old fab shop we had single phase power and got a great deal on a 3 phase lathe and mill. Price was so good we couldn't pass but did not have 3 phase power to run. Was in the same position that you are and only needed a little over a 1/4 mile of 3 phase ran to our shop, however, the nearest 3 phase was miles away and the cost would have been HUGE to have it run to our shop.

I ended up using rotary phase converters to get 3 phase and had really good luck with them. The rotary don't produce a loss in the HP of any of your equipment like the static kind do and are relatively easy to install. I got mine from Phoenix Phase converters and had great luck with them.

Hope this helps.
 
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GoldDigger

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Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Brad45 said:
At my old fab shop we had single phase power and got a great deal on a 3 phase lathe and mill. Price was so good we couldn't pass but did not have 3 phase power to run. Was in the same position that you are and only needed a little over a 1/4 mile of 3 phase ran to our shop, however, the nearest 3 phase was miles away and the cost would have been HUGE to have it run to our shop.

I ended up using rotary phase converters to get 3 phase and had really good luck with them. The rotary don't produce a loss in the HP of any of your equipment like the static kind do and are relatively easy to install. I got mine from Phoenix Phase converters and had great luck with them.

Hope this helps.
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Use of a properly rated VFD will not only cause no loss of HP but will also provide optional speed control and very soft starting.
You would have to make sure that the motor is inverter rated or else use a sine wave filter or large load reactor on the VFD output.
 
G

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
180115-1705 EST

GoldDigger:

Those features would not be of any value with two machines that might run simultaneously. If just running one machine at a time, and either or both machines are CNC, then not likely of much value.

A rotary phase converter may have the advantage of riding thru short duration power problems by adding inertia to the inverter. In some cases a lot of money can be lost if power is interrupted to a CNC causing a crash.

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I

Ingenieur

Senior Member
Location
Earth
how many machines require 3 ph
all motors?
approximate load for each


on another note
a $30 mil home and using 50k for a 3 ph upcost
0.17% increase
that should be moot if you can afford a 30 mil home
 
G

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
180115-2345 EST

electrofelon:

I have not experimentally tried it, but I don't believe there should be a significant problem. Of course one would probably want to use two identical units.

The two single phase input wires are a pass thru anyway. Phasing would need to be correct on the third wire. This is just a matter of how the motors are wired. The two single phase wires have a source impedance defined by the power company (unless we add a large inertia load on the converters and look at transient loss of single phase power).

I would expect the internal impedance when looking back at the converter third wire would be about equal for each converter. Thus, the generated phase should balance fairly well.

.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
gar said:
180115-2345 EST

electrofelon:

I have not experimentally tried it, but I don't believe there should be a significant problem. Of course one would probably want to use two identical units.

The two single phase input wires are a pass thru anyway. Phasing would need to be correct on the third wire. This is just a matter of how the motors are wired. The two single phase wires have a source impedance defined by the power company (unless we add a large inertia load on the converters and look at transient loss of single phase power).

I would expect the internal impedance when looking back at the converter third wire would be about equal for each converter. Thus, the generated phase should balance fairly well.

.
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Do you think you would have them paralleled at start up, or let them spin up then parallel?
 
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