Origins of Stray Voltage |
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We have seen that stray voltage occurs when an animal touches two
points of a voltage gradient at the same time
[Gd Causes SV].
But what causes these voltage gradients and
how do they relate to farm and utility power systems?
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Current flowing through the earth causes voltage gradients,
as we have seen earlier [What Is Gd?].
In this case, the current is a portion of the neutral current
that flows through the earth rather than on the neutral conductor when
grounding is present.
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There are two distinct neutral currents on
the electric power system that begin to flow when a customer turns on an electric
appliance. One current is on the supply circuit (utility neutral current) and the other
is on the utilization circuit (customer neutral current).
Although these two currents mix in the earth, they are distinct enough to merit
separate discussion.
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Let's start by reviewing how a typical power system looks and operates
[Power Systems].
This will help us better understand where these currents originate
and how they flow into, out of, and through the earth, creating voltage gradients. |
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We then examine these two currents separately, looking at voltage
gradients on the supply side
[Supply Side Gd]
and on the utilization side
[User Side Gd].
We look at the actual case in which these two
gradients come as a pair [Both Gradients],
and the complication added as the two currents
intermingle in the earth [Intermingling].
We also consider briefly the relative effect of each of
these loop currents on the final gradients
[Differences]. |
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We have made these explanations as simple as possible. The subject matter is,
however, quite complicated. The following diagram provides a guide to the
discussion that follows. Please refer to it throughout the discussion
to see how the various pieces fit together . |
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The subject of neutral-to-earth voltage is addressed at the end of this
presentation [Neutral Voltage]. |
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