It was learned that
the key effect sag? We know that mutual spacing of the conductive and Span Length: -
Interval must be sufficient so that the overhead lines of mutual conductive All side of air and air ayounized insulation can not break down.
The distance between two conductive to the two sources are used.
. Mutual interval = (0.01Vkv + 1.24D / W √ d) feet ............... (i)
Where,
Vkv = Voltage (kv)
D = conductor diameter (inch)
W = weight per unit length of conductor (ft)
d = sag (ft)
. Mutual interval = (0.075 √ d + Vkv ² / 20000) meters .................. (ii)
. Where d = sag (meters)
Overhead line conductor of the different types of mutual minimum distance of the voltage. A list is given.
Interval must be sufficient so that the overhead lines of mutual conductive All side of air and air ayounized insulation can not break down.
The distance between two conductive to the two sources are used.
. Mutual interval = (0.01Vkv + 1.24D / W √ d) feet ............... (i)
Where,
Vkv = Voltage (kv)
D = conductor diameter (inch)
W = weight per unit length of conductor (ft)
d = sag (ft)
. Mutual interval = (0.075 √ d + Vkv ² / 20000) meters .................. (ii)
. Where d = sag (meters)
Overhead line conductor of the different types of mutual minimum distance of the voltage. A list is given.
|
Operating
voltage
|
Vertical
spacing
|
Horizontal
spacing
|
Spacing
between conductor & support
|
|
400/300
V
|
46 cm
|
38 cm
|
15 cm
|
|
11 KV
|
76cm
|
115
cm
|
31 cm
|
|
22 KV
|
91cm
|
137
cm
|
46 cm
|
|
33 KV
|
122cm
|
153
cm
|
61 cm
|
|
66 KV
|
200cm
|
325
cm
|
76 cm
|
|
110
KV
|
315cm
|
495
cm
|
110
cm
|
|
132
KV
|
370cm
|
590
cm
|
130
cm
|
|
230
KV
|
645cm
|
1028
cm
|
226
cm
|
If it is possible to create low-cost Transmission lines may be useful. The maximum limit for the line span (optimum) to be. The support and Fixture such as the number of Insulator decreases, the cost will be lower. However, due to the increase in October sag support height will increase, while the conductor spacing, increasing cross - arm's length will increase. Span length of the line to create a way to control costs should be increased, and the other kit is a high cost.
Below the economic optimum span Powered_by_gitorious (most economical span length) and a different type and height of the support line and voltage sag and span of the Table: -
|
Line voltage (Voltage)
|
Type of support(Meters)
|
Hight of supports
(Meters)
|
Approx. Sag
(Meters)
|
Approx. Span
(meters)
|
|
400/300 V
|
Wooden,concrete,tubular
|
8.5-9.0
|
0.5-1.0
|
50-70
|
|
11000 V
|
Tubular, rail
|
9-10
|
1.0-1.5
|
80-120
|
|
33000 V
|
Rail pole
|
10-12
|
1.4-1.8
|
110-130
|
|
66000 V
|
Tower
|
20-25
|
2.0-3.0
|
180-240
|
|
132000 V
|
Do
|
25-30
|
4.5-6.0
|
250-350
|
|
2220000 V
|
Do
|
30-40
|
7.0-9.0
|
300-400
|
|
380000 V
|
Do
|
35-45
|
8.0-10
|
350-430
|
|
|
|
|
|
|
Notes:1. - An overhead line span 200m. Conductor cable cross 3cm ² meters and weight of 0.85kg. 2000 kg per cm ² and a safety factor of 2 when the maximum meaningful tension wire sag calculate tax?
Ans: - here,
m = 220 m, A = 2cm ², W / m = 0.85 kg.
The maximum meaningful tension = 2000 kg / cm ², safety factor = 2
d =?
We know, meaningful tenasana = maximum strength (strain) × cross / Safety Factor
T = 2000kg/cm ² × 3 cm ² / 2
= 3000 kg
Sag d = Wm ² / 8T
Ans. = 0.85 × (200) ² / 8 × 3000 = 1.71 m.
Notes: 2 - a river on a transmission line to the water surface and 30 m height, with the help of two tower has been constructed. Horizontal distance between towers 300 m. If the maximum strain carrying weight of 1590 kg and 0.8 kg All meters is, but how much above the river between the water surface may be conductive?
Ans: - P1 = 30 m, P2 = 40 m
T = 1590 kg, W / m = 0.8 kg
h = P1-P2 = 10 m
m = 300 m, H =?
Now,
X1 = m / 2 - Th / Wm
= 300/2 - 1590 × 10 / 0.8 × 300 = 83.75 m.
X2 = m / 2 + Th / Wm
= 300/2 + 1590 × 10 / 0.8 × 300 = 216.25 m.
X = m / 2-X1
= 150 - 83.75 = 66.25 m
d = W X ² 2/2T = 0.8 × (66.25) ² / 2 × 1590 = 1.1 m.
d2 = W X ² 2/2T = 0.8 × (216.25) ² / 2 × 1590 = 11.76 m
H = P2 - d2 + d = 40 - 11.76 +1.1
Ans = 29.34 m.
Tips: - 1. How many and what size sag?
Ans = There are three different ways, namely: -
1. Sag board method.
2. Dynamo meter method
3. Stop watch or return wave method.
Tips: - 2. There are two common species to carrying out the distance between you?
Ans = Mutual interval = (0.75 √ d + Vkv ² / 20000) meters.
Tips: - 3. Sag span of approximately 132 kv line support and how much?
Ans = 132 kv for -
Sag scale: 4.5 - 6 m.
Scale span: 250 - 350 m.
Tips: - 4. Span is allowed and the 220 kv sag?
Ans = Respectively 8 – 10 m. and 350 - 430 m.
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