Some help with understanding these terms

[SKJ25POL]

Hi
To people that have worked and experienced in Transmission Line design, may I ask when they are asking a person like me (no Transmission Line background), what each means and where I can find some sources to educate myself? I greatly appreciate a sketch since I am visual person and can understand visual better.

Thank you


1) angle of deflection due to wind

2) moment at the base of pole due to horizontal and vertical loads on a pole,

3) anchor load given horizontal line tension

4) vertical column load given horizontal line tension

5) line sag comparison of two voltages with given power


6) grounding scheme of a switch pole

 

[waross]

6) Grounding scheme at switch pole.
It is common to use an equi-potential mat or grid at switch poles.
AN EQUI-POTENTIAL MAT NOT A GROUNDING METHOD.
The purpose of the mat is to maintain the switch operating handle at the same potential as the body of the person operating the switch.
An equi-potential mat may be 1 meter x 2 meters.
It is connected to the switch handle by one or two conductors.
There must be no connections to ground nor to any other point other than the switch handle.
The mat may be surface mounted.
The mat may be covered with one or two inches of substation grade crushed rock.
The mat may be permanent or it may be carried on a service truck and installed prior to switching.
Ground fault currents are not expected to flow in the equi-potencial mat or the equi-potencial mat conductors.

5) Line sag is a physical property depending on line strength, line tension, distance between poles or towers and ambient temperature.

4) Vertical column load is not related to line tension.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[SKJ25POL]

waross (Electrical,
Bill
Thank you for your response. Can I ask what is switch pole, i mean how a switch pole is different than other poles? Is it taller, shorter, is it the deadend structure?
Physically how different is a switch pole? I assume it is a steel pole like a transmission pole, am I right?

 

[KillBill7]

1) For structures, this probably means pole tip deflection due to the transverse wind load on the structure. Some utilities limit the deflection to the certain percentage of the above ground pole length and others don't care as far defection doesn't cause any electrical clearance issues.

2) These are your ground reactions (vertical force, shear force and bending moment) at the base of the pole due to wire tensions and wind/ice loads. This information is required for the foundation design of the structure.

3) Anchor loads are the sum of max tensions in the guy wires attached to that anchor. You will need anchor loads in addition to the geotechnical report to select the suitable anchor for your structure.

4)refer to Warros's reply

5)refer to Warros's reply

6) Structurally speaking, Switch structure is same as any other structure except it has the additional vertical load of the switch. Refer to Waross's post for switch grounding.

 

[davidbeach]

It’s a pole with a switch. What that means in practice varies tremendously by voltage and the practices of the owning utility.

 

[waross]

The switch frame on a switch pole will also be grounded.
If the event of a fault the heavy fault current may cause step and touch voltages on various conducting objects.
In the event that fault currents cause a rise in voltage on the surface of the operating handle, the equi-potential mat will keep the operator at the same potential as the switch handle, and keep him safe from shocks.
An equi-potential mat must be connected to the switch handle only and not grounded in any way.
Yes, I said that before, but it is important enough to repeat.
Improper installation of an equi-potential mat may result in an otherwise avoidable death.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[dauwerda]

Vertical column load is related to line tension if the pole is guyed - This is really the only time vertical column load has any significance on the pole and foundation design.

Switch poles often have tighter deflection requirements on them as large deflections will negatively affect the operation of the switches.

Anchor load seems to be referring to the anchors of guy wires - this will be driven by line tension as well as the angle of installation of the guy wire(s)