Prevention of transmission line construction problems

In the place where induction electricity is generated, the construction of transmission lines or the maintenance of the ground conductor of the transmission line will produce induced voltage, and the human body will form a current loop when touching the ground wire with induced voltage, and the current passes through the human body, so that part or the entire body is stimulated and injured by electricity, causing human injury, and in severe cases, it will cause casualties
.
People need to raise awareness
about the dangers of electric shock.

Induced electrical problems include induced voltages and induced currents
resulting from electromagnetic induction.
If the transmission line that generates the induced current is not grounded, only the induced voltage is present; Once the line is grounded, an induced current
into ground is generated.
The induced electricity of the nearby lines of the transmission line in operation generally comes from two aspects: one is electromagnetic induction, which is related to mutual inductance: and the other is electrostatic induction, which is related
to capacitance.
According to the literature, the factors affecting the size of the induced current are: line operation status (the size of the grounding line resistance and grounding position of the construction transmission line, the running line load, the operation of the running line, etc.
), the length of the parallel line, the distance between phases and loops, the number of conductor splits per phase, the height of the conductor and the transposition mode of the line
.

Because the induced electric is induced by the high-voltage electric field generated by the adjacent parallel or crossed live line through the air medium, and is related
to the voltage of the live line, the distance between the lines, the parallel length and the meteorological conditions.
When a line is erected near a parallel running transmission line, an electrostatic induced voltage is generated when the conductor is suspended, and an induced current
is generated if grounded.
The induced voltage is related to the capacitance, that is, to the relative position of the wires, and not to the length parallel to them; In addition to the capacitance to the ground, the induced current also increases with the increase of parallel length, the closer the distance between the construction transmission line and the running line, the larger the running wire current, the higher the induced voltage generated on the construction transmission line, the greater the risk of induced electric shock
.

Since the induced electric is induced by the high-voltage electric field generated by the adjacent parallel or crossed live line through the air medium, it has a certain concealment, and it is easy to cause personnel electric shock and high-altitude fall accidents
.
In order to prevent injuries caused by induction electricity to workers on transmission lines, the following measures should be taken:

Organize construction personnel to learn the principle of induced voltage generation and related factors that affect the size of induced voltage (such as: voltage, current, distance, etc.
).

In order to improve the construction personnel's awareness of the concealment and danger of induced voltage, consciously abide by the measures
to prevent induced voltage shock.

Set up a temporary working ground wire
.
The value of the induced current is sometimes as high as several thousand volts, but usually the energy is limited, and as long as the line of the power outage is reliably grounded, the induced voltage value will quickly drop to zero
.
Temporary grounding wires can be divided into portable temporary working grounding wires and personal security auxiliary grounding wires
according to their use.

Because the length of high-voltage transmission lines is more than 100 kilometers, the climate change between regions is large
.
The distance between two adjacent transmission lines is more or less, and the capacitance, inductance and resistance between the transmission lines are distributed along the line, so the potentials of each point of the line are not equal
.
Therefore, for line construction, relying only on the grounding wire at both ends of the line cannot guarantee that the construction point potential is ground potential
.
Therefore, the grounding wire must be hung at the construction site, and for the operation of the upper pole, the construction personnel must tie the safety belt and work between the grounding wires, and must not risk the operation without hanging the
grounding wire.

Before dismantling the simple grounding conductor installed on the construction transmission line to prevent inductive electric shock, a regular working grounding wire should be installed, and only after removing the simple grounding wire can the regular ground wire be removed using an insulating rod and wearing insulating gloves
.
Equipped with a special simple ground wire
that is easy to carry and use with personal inductive electric shock.

1.
Because the generation of induced voltage is related to many factors, the value of the induced voltage of 500kV overhead transmission line can reach tens of kilovolts, if no measures are taken, it may threaten the personal safety of construction personnel, therefore, the construction transmission line or electrical equipment near the operation of high-voltage transmission line should be regarded as a live body
.

2.
Hanging grounding wires on construction transmission lines is an important measure
to reduce the induced voltage along construction transmission lines.
By hanging the grounding wire at the first end and in the middle of the construction transmission line, the induced voltage
along the decommissioned line can be effectively reduced.
The construction transmission line in the electromagnetic field of the running line, after grounding at one end of the line, the induced voltage decreases rapidly, but there may still be hundreds of volts of voltage, and the farther away from the grounding point, the greater the induced voltage, so adding a grounding wire at the construction point is particularly effective
in reducing the induced voltage at the point.
In addition, the influence of the tower grounding resistance on the induced voltage is also very obvious
.

In short, in the construction process of power grid transmission lines, we must attach great importance to the understanding of induction voltage electric shock and injury, carefully follow the requirements of safety work regulations, do a good job of preventive measures, and must not act according to the so-called "experience
".