Electrical transmission line design and its different coordination at different voltage level

Electrical transmission Line design and its coordination at different voltage levels

Indian economy is increase by 8 % per annually. So at energy level there is also need for increment around 10 % annually. India now stands at 3^rd   ranked followed by China and USA in list of electricity generation around world. Total generation of India is 3, 71,050 MW, and annually output around 700 billion unit. Power Grid Corporation of India limited (PGCIL) now has a network around 68,000 ct.km of transmission line system. Power Grid Corporation of India limited is main establishment, that’s designed whole transmission system. PGCIL now has 81 % of India’s inter states transmission system. In India now has Central transmission utility and 32 state transmission system department. In India total energy generation dominated by government, government own 83 % Power plants generation and transmission system. Only 17% of energy generation by private sector and only 14 % distribution by private sector. India now has total transmission line length up to 220 kV is around 414, 900 ckt.km, including high voltage alternating current substations capacity around 885, 900 MVA and high voltage dc current capacity around 22,500 MW.

Here some of the coordination mentions that will help you to understand transmission line design and its characteristics

Transmission Line VS its Line loading in kW/km

Transmission line voltage Line to Line (kV)	Line Loading (kW/km)
11 kV	24×103  kW/km
33 kV	200×103 kW/km
66 kV	600×103  kW/km
110 kV	11×106  kW/km
132 kV	20×106 kW/km
166 kV	35×106  kW/km
230 kV	90×106  kW/km
400 kV	100×106  kW/km

 

Minimum and Maximum length of line to line voltage of Transmission line at different voltage level

Transmission line voltage Line to Line (KV)	Length of line in (km)
	Minimum Length (km)	Maximum Length (km)
11 kV	15 km	30 km
33 kV	30 km	60 km
66 kV	40 km	120 km
110 kV	50 km	140 km
132 kV	50 km	160 km
166 kV	80 km	180 km
230 kV	100 km	300 km
400 kV	300 km	400 km

Transmission line to line Voltage VS Equivalent spacing between conductors

Transmission line voltage Line to Line (kV)	Equivalent spacing in (m)
11 kV	1 m
33 kV	1.3 m
66 kV	2.6 m
110 kV	5 m
132 kV	6 m
166 kV	8 m
230 kV	10.2 m
400 kV	14 m

Transmission Line VS which type of Insulator use

Transmission line voltage Line to Line (kV)	Insulator use
11 kV	Pin type
33 kV	Pin type
66 kV	Suspension type
110 kV	Suspension type
132 kV	Suspension type with increasing number of discs
166 kV	Suspension type with increasing number of discs
230 kV	Suspension type with increasing number of discs
400 kV	Suspension type with increasing number of discs

 Transmission Line of different voltage VS Number of Insulator Disc used

Transmission line voltage Line to Line (kV)	Number of Insulator discs use
11 kV	1
33 kV	2
66 kV	5
110 kV	8
132 kV	10
166 kV	12
230 kV	16
400 kV	22

 

Transmission line at different voltage VS Surge Impedance Loading (SIL)

Transmission line voltage  Line to Line (kV)	Length of line in (km)		Surge Impedance loading (SIL) in (MW)
	Minimum Length (km)	Maximum Length (km)
11 kV	15 km	30 km	0
33 kV	30 km	60 km	0.1
66 kV	40 km	120 km	0.2
110 kV	50 km	140 km	0.2
132 kV	50 km	160 km	0.2
166 kV	80 km	180 km	0.4
230 kV	100 km	300 km	0.6
400 kV	300 km	400 km	0.8

Transmission line at different voltage VS Line support for overhead line

Transmission line voltage  Line to Line (kV)	Line Support
11 kV	Wooden Pole
33 kV	Steel Pole
66 kV	Latticed steel structure
110 kV	Latticed steel structure with narrow base
132 kV	Latticed steel structure with narrow base
166 kV	Latticed steel structure with broad base
230 kV	Latticed steel structure with broad base
400 kV	Latticed steel structure with broad  base

Transmission line at different voltage VS Line support for overhead line VS Span length between two Line support structures

Transmission line voltage Line to Line (kV)	Line Support	Span Length in (M)
11 kV	Wooden Pole	50 m
33 kV	Steel Pole	60m – 100m
66 kV	Latticed steel structure	100m – 200m
110 kV	Latticed steel structure with narrow base	250m – 300m
132 kV	Latticed steel structure with narrow base	300m
166 kV	Latticed steel structure with broad base	300m
230 kV	Latticed steel structure with broad base	300m
400 kV	Latticed steel structure with broad  base	More than 300m

 

Transmission line at different voltage VS Minimum clearance require from ground to lowest point of sag of transmission line’s conductor in meter

Transmission line voltage Line to Line (kV)	Minimum clearance require from ground to sag’s middle point in (m)
11 kV	5.8 m
33 kV	5.8 m
66 kV	6.0 m
110 kV	6.4 m
132 kV	6.7 m
166 kV	6.7 m
230 kV	7.0 m
400 kV	8.0 m

Transmission line at different voltage VS Standard basic insulation level of conductor

Transmission line voltage Line to Line (kV)	Standard basic insulation level of conductor in  (kV)
11 kV	77 kV
23 kV	150 kV
33 kV	179 kV
46 kV	250 kV
66 kV	328 kV
69 kV	350 kV
110 kV	525 kV
115 kV	550 kV
132 kV	610 kV
138 kV	650 kV
161 kV	750 kV
166 kV	845 kV
230 kV	1050 kV
287 kV	1300 kV
345 kV	1550 kV
400 kV	1580 kV

Transmission line at different voltage VS which type of cable use for transmission of power

Transmission line voltage Line to Line (kV)	Types of cable use
11 kV	Belted cable
33 kV	H type cable
66 kV	H type cable
110 kV	Separate lead sheathed cable
132 kV	H type separate lead sheathed cable
166 kV	Gas filled cable
230 kV	Oil filled cable
400 kV	Oil filled cable

Transmission line at different voltage VS require voltage regulation for power system

Transmission line voltage Line to Line (kV)	Voltage regulation in Percentage (%)
0.415 kV	6 %
11 kV	9 %
33 kV	9. 2 %
66 kV	9.5 %
110 kV	9.8 %
132 kV	10 %
166 kV	11 %
230 kV	13 %
400 kV	14 %

Transmission line at different voltage VS Highest system voltage line to line

Normal Transmission line voltage Line to Line in  (kV) r.m.s	Highest system voltage line to line in  (kV) r.m.s
3.3 kV	3.6 kV
6.6 kV	7.2 kV
11 kV	12 kV
15 kV	17.5 kV
22 kV	24 kV
33 kV	36 kV
47 kV	52 kV
66 kV	72.5 kV
88 kV	100 kV
110 kV	123 kV
132 kV	145 kV
150 kV	170 kV
166 kV	215 kV
230 kV	245 kV
400 kV	420 kV

Transmission line at different voltage VS Insulation of conductor hold highest system impulse withstand voltage also call as Crest voltage

Normal Transmission line voltage Line to Line (kV) r.m.s	Highest system impulse withstand voltage in  (kV)
3.3 kV	45 kV
6.6 kV	60 kV
11 kV	75 kV
15 kV	95 kV
22 kV	125 kV
33 kV	170 kV
47 kV	250 kV
66 kV	325 kV
88 kV	450 kV
110 kV	550 kV
132 kV	650 kV
150 kV	750 kV
166 kV	788 kV
230 kV	1050 kV
400 kV	1550 kV

Transmission line at different voltage VS Insulation level of conductor manage power frequency withstand for 1 minute constant without breakdown of insulation

Normal Transmission line voltage Line to Line (kV) r.m.s	power frequency withstand for 1 minute constant voltage in  (kV)  r.m.s
3.3 kV	21 kV
6.6 kV	27 kV
11 kV	35 kV
15 kV	45 kV
22 kV	55 kV
33 kV	75 kV
47 kV	105 kV
66 kV	140 kV
88 kV	182 kV
110 kV	230 kV
132 kV	275 kV
150 kV	325 kV
166 kV	360 kV
230 kV	460 kV
400 kV	680 kV

Basic ratings of Lightning Arrester about rated voltage of arrester VS Possible highest impulse spark over voltage that can handle up to 10 kA

Rated voltage of arrester in (kV)	Highest impulse spark over voltage in (kV) for arrester up to 10 kA
10 kV	33.6 kV
13 kV	44 kV
16 kV	55 kV
19 kV	66 kV
22 kV	77 kV
25 kV	88 kV
28 kV	98 kV
31 kV	109 kV
34 kV	120 kV
37 kV	131 kV
61 kV	217 kV
76 kV	271 kV
97 kV	325 kV
121 kV	401 kV
139 kV	454 kV
187 kV	611 kV
199 kV	650 kV

Basic ratings of Lightning Arrester about rated voltage of arrester VS Possible manage maximum Residual voltage by Lightening arrester 

Rated voltage of arrester in (kV)	Maximum Residual voltage in (kV)
10 kV	33.6 kV
13 kV	44 kV
16 kV	55 kV
19 kV	66 kV
22 kV	77 kV
25 kV	88 kV
28 kV	98 kV
31 kV	109 kV
34 kV	120 kV
37 kV	131 kV
61 kV	217 kV
76 kV	271 kV
97 kV	325 kV
121 kV	401 kV
139 kV	454 kV
187 kV	611 kV
199 kV	650 kV

Note: - Possible holding maximum residual voltage by lightning arrester is same as Possible manage maximum Residual voltage by Lightening arrester  

Basic ratings of Lightning Arrester about rated voltage of arrester VS Possible holding capacity for maximum front of wave’s spark over voltage for lightning arrester up to 10 kA current capacity

Rated voltage of arrester in (kV)	for maximum front of wave’s spark over voltage in (kV) for lightning arrester up to 10 kA
10 kV	39 kV
13 kV	58 kV
16 kV	63 kV
19 kV	76 kV
22 kV	89 kV
25 kV	101 kV
28 kV	113 kV
31 kV	126 kV
34 kV	138 kV
37 kV	151 kV
61 kV	251 kV
76 kV	311 kV
97 kV	372 kV
121 kV	464 kV
139 kV	523 kV
187 kV	703 kV
199 kV	748 kV

Basic ratings of Lightning Arrester about rated voltage of arrester VS Maximum front wave steepness voltage

Rated voltage of arrester in (kV)	Maximum front wave voltage in (kV)
10 kV	77 kV
13 kV	101 kV
16 kV	125 kV
19 kV	151 kV
22 kV	177 kV
25 kV	202 kV
28 kV	225 kV
31 kV	251 kV
34 kV	275 kV
37 kV	301 kV
61 kV	501 kV
76 kV	621 kV
97 kV	741 kV
121 kV	845 kV
139 kV	1032 kV
187 kV	1175 kV
199 kV	1215 kV