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Neutral Flow




Origo Corporation Neutral Flow
1





� Origo Corporation 2004
Technology Made Simple

Neutral Flow

The current assumption is that neutral current flow is just part of the cost of doing business because of
the high cost of locating and correcting it. Actually, it is the large number of phasing mistakes that have
complicated attempts to correct it.

Imagine, as a Load Specialist, spending hours upon hours trying to define changes that needed to be
made to correct high amps on a feeder only to find out that once the field personnel had done their job,
the amps still existed. What they thought was A was actually C; but where was it rolled, or where were
the tags wrong? The PhaseID System offers a simple solution. Phase identify your system.

To see why neutral current is undesirable, just ask what it costs to push unused amps back to the source
on the neutral line. No doubt, we do have to live with some neutral current flow. However, neutral flow
will be less on a system that has been phase balanced. The savings from reduced neutral flow range
anywhere from thousands to millions of dollars in wasted fuel costs, depending on the scale of your
distribution system and the imbalances that exist. Here is how you calculate the savings.


Step 1: Find an example
Lets use as a sample, one mile of #6 Copper neutral on a feeder and lets put 50 amps of neutral
flow on it as an average.

Step 2: Determine Power Loss
Now, calculate the power loss by using the formula I squared R, with the resistance of #6
Copper as the R variable. We know from tables that a mile (5,280 feet) of #6 has 2.59 ohms of
resistance. This gives us 6,475 watts existing on our mile of line.
50 amps squared, then multiplied by 2.59 ohms of resistance = 6475 watts of power loss

Step 3: Convert to kWh per year
To convert the 6474 watts of power loss into kilowatts that exists on our sample line we must
convert the watts into kilowatts and then multiply by the number of hours in a year.
6475 multiplied by .001, then multiplied by 8760 hours = 56,717 kilowatts of power loss per
year

Step 4: Determine cost
What is the cost of producing a kWh? Lets assume .03 cents.
56,717 multiplied by .03 = $1701.52

Step 5: Develop a headache
You have now wasted $1,701.52 dollars on one mile of line over one year. What if you have 100
feeders in your system and they all have neutral flow at this magnitude? How many feeders are
there? Better yet, how many miles in every feeder? Lets imagine the same numbers for 700
miles of lines or 700 feeder miles. The loss number increases to
1,191,064 dollars per year
.








Origo Corporation Neutral Flow
2





� Origo Corporation 2004
Technology Made Simple

The numbers can get even more dramatic. Especially when you consider the fact that I squared
R is the basis of the formula. You see, 10 amps x 10 amps only equals 100 but 50 x 50 equals a
whopping 2500. The square is the heart of the I�R problem and the problem is exponential as the
amperage increases. The savings come when you reduce the amperage. Amperage only has to
go down a little to reap huge rewards. You can see in the last column that by reducing a 50 amp
neutral imbalance down to a 20 amp imbalance saves over
$1 Million
.

All kidding aside, we all know you cant completely take away neutral flow. Its part of doing
business. But what if we can now reduce all of our feeders by only 20 amps because now we
know which phase were installing, moving or replacing? I squared R works both ways. So why
not use it to our advantage?













Neutral
Wire
AWG
Resistance
#6 Copper
per Mile
Neutral
Amps
Watts Lost per
Feeder Mile
( FM )
KWH Lost per
Feeder Mile
per Year
Loss in Dollars
1 Mile of #6 Copper
1 Year @ .03KWh
Loss in Dollars
700 Mile of #6 Copper
1 Year @ .03KWh
$$$ Savings
by Reducing
700FM by 10 Amps
$$$ Savings
by Reducing
700FM by 20 Amps
$$$ Savings
by Reducing
700FM by 30 Amps
2.58984
10
258.984
2268.700
$68.06
$47,642.70
2.58984
20
1035.936
9074.799
$272.24
$190,570.79
$142,928.09
2.58984
30
2330.856
20418.299
$612.55
$428,784.27
$238,213.48
$381,141.57
2.58984
40
4143.744
36299.197
$1,088.98
$762,283.15
$333,498.88
$571,712.36
$714,640.45
2.58984
50
6474.600
56717.496
$1,701.52
$1,191,067.42
$428,784.27
$762,283.15
$1,000,496.63
2.58984
60
9323.424
81673.194
$2,450.20
$1,715,137.08
$524,069.66
$952,853.93
$1,286,352.81
2.58984
70
12690.216
111166.292
$3,334.99
$2,334,492.14
$619,355.06
$1,143,424.72
$1,572,208.99
2.58984
80
16574.976
145196.790
$4,355.90
$3,049,132.58
$714,640.45
$1,333,995.51
$1,858,065.17
2.58984
90
20977.704
183764.687
$5,512.94
$3,859,058.43
$809,925.84
$1,524,566.29
$2,143,921.35
2.58984
100
25898.400
226869.984
$6,806.10
$4,764,269.66
$905,211.24
$1,715,137.08
$2,429,777.53
#6 CU