Estimation Of Materials Required For LT Lines Or Low Tension Line
Hello guys, welcome back to our blog. Here in this article, we will discuss the estimation of materials required for LT lines or low tension lines, problems on LT lines or low tension lines and we will explain each and every component.
If you have any electrical, electronics, and computer science doubts, then ask questions. You can also catch me on Instagram – CS Electrical & Electronics.
Also, read:
- Top 12 Electrical Switch Manufacturing Companies In The World
- Top 13 Websites For Research Papers For Engineers, MTech Students
- Types Of Testing Done On Electric Vehicles Before Launching
Estimation Of Materials Required For LT Lines
01. No of spans
= Length of line ÷ span
What is the span?
Span means horizontal distance between two poles is called span. A number of spans mean for example in a 1000 KM line how many spans are there?
02. No of supports
= No of spans + 1 ( for taping pole )
Supports mean nothing but poles that give support to the conductors. A number of support means in the 1000 KM line how many supports are there.
03. R.C.C poles are used at starting, deviation points, and anchoring points
R.C.C full form is reinforced cement concrete, this pole is constructed using concrete and with some rods. This pole is very strong compared to the other pole. R.C.C pole cannot break easily, it can hold heavy weight.
04. P.C.C poles are used at intermediate poles only.
P.C.C pole’s full form is plain cement concrete, this pole is weak in tension and it is constructed only by using cement concrete.
05. No of cross-arms
No of 4-pin cross-arm = No of support + 1 ( tapping pole )
cross-arms which gives support to the insulators and conductors. cross arms are classified into many types; V shape cross arm, horizontal cross arm, U-shaped cross arm, etc.
06. No of pin insulators
= 4 [Number of supports + no of deviations – (one dead-end + anchoring points)]
Pin insulators that do not allow an electric current to flow through them, pin insulators are used if the voltage is below 33 KV.
07. No of strain insulators
= [Two (one for each dead end) + 2(number of anchoring points )]
8. Length of the conductors required :
(a). For phases, the ACSR No.2 conductor has required = 3 × lengths of line(b). For neutral, ACSR No.4 conductor has required = 1 × length of a line
The full form of ACSR conductor is “Aluminium Conductor Steel Reinforced”.
09. The number of guy sets
= 2(one for each dead end) + (Anchoring point)2 + deviation points.
10. Whenever guarding is to be provided two numbers of special cross arms with two numbers of guy sets and 15 kg 8 SWG G.I wire are to be used.
A guarding is provided for the safety of life, installation, and communication circuits.
The guarding for 11 KV lines is provided at road crossings, canal crossings, railway crossings, crossing over lt lines, or communication lines.
This was about materials required for LT lines.
Problem On Estimation Of Materials Required For LT Lines
Q: A three-phase 4 wire 415/230 V LT line has to be extended for a length of 1 KM, for electrification of a factory. Assuming an average span of 60 meters. Prepare the list of materials required for the same.
Solution :
1. Number of spans
= Length of line / span
= (1 × 1000) / 60
= 16.66 say 17 No’s
( span means the distance between two poles)
The number of spans in the one-kilometer line is 17 No.
2. Total number of supports
= Number of spans + 1
= 17 + 1 = 18 No’s
The total number of supports required for a one-kilometer line is 18 No’s.
3. Number of R.C.C poles
= one for tapping + one for dead-end + ( at 0.5 KM anchoring ) = 1 + 1 + 1 = 3 No’s
The total number of reinforced cement concrete poles required is 3 No’s.
4. Number of P.C.C poles
= Number of supports – R.C.C poles
= 18 – 3 = 15 No’s
The number of plain cement concrete poles required is 15 No’s.
5. Number of 4-pin cross arms = 18 No’s
How many poles are there that many cross arms are required.
6. Number of 1.1 KV class guy sets
= 1(starting pole) + 1(terminating pole) + 2(at 0.5 KM anchoring pole) = 4 No’s
The number of guy set required is 4 No’s.
7. Number of pin insulators
= (No of intermediate poles + Anchoring ) × 4
= (15 + 1) × 4
= 16 × 4 = 64 No’s
The number of pin insulators required is 64 No’s
8. Number of strain insulators
= 4 * [starting pole + end pole + 2(Anchoring pole)] = 4(2 + 2) = 16 No’s
9. Length of conductors
(a). A.C.S.R No.2 weasel conductors for 3-phase conductors with 3% sag = 3 × 1 KM × 1.03 = 3.09 KM
(b). A.C.S.R No.4 squirrel conductor for neutral with 3% sag = 1 × 1 KM × 1.03 = 1.03 KM
10. Miscellaneous materials such as nuts, bolts, barbed wires, etc.
List Of Materials Required For LT Lines
| SI.No | List Of Materials | Unit | Quantity |
| 01 | R.C.C poles 7.5 meters long, 140 kg working load | No’s | 03 |
| 02 | P.C.C poles 7.5 meters long, 115 kg working load | No’s | 15 |
| 03 | 4-pin cross arms with pole clamp nut, bolt, and washers | Set | 18 |
| 04 | 1.1 KV class guy set complete | Set | 04 |
| 05 | 1.1 KV pin insulators with pin and nuts complete set | Set | 64 |
| 06 | No 8 strain insulator of porcelain | No’s | 16 |
| 07 | No 2 A.C.S.R squirrel conductor with 3% sag for all line conductor | KM | 3.09 |
| 08 | No A.C.S.R squirrel conductor with 3% sag for the neutral conductor | KM | 1.03 |
| 09 | Miscellaneous materials such as nuts, bolts, washers, barbed wire, etc | Lump sum | 45 |
This was about “Estimation Of Materials Required For LT Lines“. I hope this article may help you all a lot. Thank you for reading.
Tags: Estimation Of Materials Required For LT Lines.
Also, read:
- 10 Tips To Maintain Battery For Long Life, Battery Maintainance
- 10 Tips To Save Electricity Bills, Save Money By Saving Electricity
- 100 (AI) Artificial Intelligence Applications In The Automotive Industry
- 100 + Electrical Engineering Projects For Students, Engineers
- 1000+ Control System Quiz, Top MCQ On Control System
- 1000+ Electrical Machines Quiz, Top MCQs On Electrical Machines
- 1000+ MATLAB Simulink Projects For MTech, Engineering Students
- 50 Tips To Save Electricity At Home, Shop, Industry, Office
About The Author
Prepare an estimate for a 1 km three-phase 440 V distribution line of 1.5 km length to be erected on wooden poles and starting from LT box of 100 kVA 11000/440 V distribution transformer. Also calculate the approximate cost involved in executing this work.
(I am not able to understand the first line of this question. This question has been given to us by our professor. I am currently studying in IIT Roorkee. Please reach to some solution asap because I have to submit this report to him by tomorrow’s lunch time)
Sure, We will try.