Download cellules cep14/15 medium voltage

CELLULES
MEDIUM VOLTAGE
CEP14/15
Thoughts on the distribution of electrical energy
950 V—3200 V—5500 V—6600 V
2
CONTENTS
GENERAL :
 The receivers………………………………………………………………………………. p. 4
 Network transformer in a pit or compact substation………………………………………. p. 4
 The LV sub network………………………………………………………………………..p. 5
 The TIT transportation network…………………………………………………………… p. 6
 Earthing scheme…………………………………………………………………………… p. 7
 Pipes calculation……………………………………………………….……….…………..p. 9
 Transformer substation…………………………………………………………………..…p. 10
 Dimmer……………………………………………………………………………………. p. 10
 TIT network control ………………………………………………………………..………p. 10
TOOLS :…………………………………………………………………………………….
p. 11
APPLICATION EXAMPLE :…………………………………………………..…………
p. 12
APPENDIX :
 Number of lamps per TIT / LV network transformer………………………….……………..
 Choice of the LV cable section………………………………….……………………………
 Dimensions of prefab concrete pits………………………………………….………………..
 Choice of MV cable section………………………………………………………………….
 Appearing impedance of MV and LV cables…………………………………………….…..
 Voltage drop calculation……………………………………………………………………...
 Choice guide of transportation voltage level to supply an end of line load…………………..
 Choice of 950 V cable section………………………………………………………………...
p. 18
p. 19
p. 20
p. 21
p. 23
p. 24
p. 26
p. 29
GLOSSARY
LV
MLV
HCP
MV
NP
TIT
: Low Voltage.
: Maximum Low Voltage.
: High Cutting Power.
: Medium Voltage.
: Nominal Power.
: Gathers MLV and MV Voltages
Standards : NFC 17-200 from March 2007, NFC 52-410 from 1978
This document is not an exhaustive study, but is merely a collection of observations and advice aimed at aiding
specialists.
Augier takes no responsibility for use of advice on all previous and future installations.
3
TIT Installation Conception
GENERAL :
The Receiver :
The types of power receivers can be very varied. The parameters below are used to characterize them. Some are
directly associated with the type of power receiver and so do not need to be recorded.
 The type of receiver.
 Power supply voltage and tolerances.
 Phase system (single or three phase).
 Power rating, start-up characteristics (overcurrent, cycle and duration).
 The type of use: continuous, cyclic or occasional.
 The conditions for simultaneous operation and simultaneous start-up of several power receivers, if
necessary, both in steady state and at start-up.
 The degree of continuous operation requirement.
NETWORK TRANSFORMER IN A PIT OR COMPACT SUBSTATION:
In the chapter below, the transformers of network or mini substation will be called "step down sub-station ".
The step down sub-station is used to supply a power receiver or group of power receivers.
The locations of the step down sub-stations and the configuration of the power receivers are determined according
to conditions in the field, relating to installation of these stations and laying of LV lines, by an economic optimization
calculation that takes into account the costs of the stations and LV cables, as well as the installation costs.
The step down station’s power rating is determined by adding together the power of the supplied power receivers. In
addition the following factors will be taken into account :
 Power efficiencies and factors, accessory power consumption, and possibly an incrementation factor, to
determine the theoretical current.
 Permissible limits for power supply voltage when operating in steady state and at start-up.
 Ambient temperature conditions.
 The current/voltage characteristics of the power consumers, the predictable deterioration in electrical
efficiency due to ageing, the possible extensions, to determine a working current.
 The start-up characteristics to define a start-up current, possibly after application of an incr ementation
factor.
The coupling of the step down tr ansfor mer will be single or thr ee phase, depending on the design of the LV
sub-network (see below).
4
There are two possible types of step down sub-station, depending on its power and installation conditions :
 Either a TED step down station, normally installed as infrastructure in an inspection pit (power limited
to 160 kVA). This is an operational complete unit, equipped with two plug-in TIT terminals to ensure
line continuity to the downstream sub-station, comprising the TIT/LV transformer, the TIT and LV protection, and the LV output which can be either a 6 meters cable or a plug-in terminal.
Pits of watertight transformers must offer an inside volume at least equal to four times the transformer volume. In
addition, they must allow cable inputs and their connection with respect to curving radius values indicated by the
cable constructor.
Transformers’ pits can be prefab. They must be composed of a grill equipped with a locking device by a special
screw, which forbids the access to the transformer until the TIT input is not opened at the installation origin, put
in circuit breaker and on earth (according to NF C 17 200 standard for road lighting installations).
 Or a compact internal or external station, depending on the installation conditions, comprising a dry varnish
impregnated transformer.
Outdoor type compact substations are designed to be installed on a concrete base, with cable output and input
from the ground, under plastic wrapping.
The step down sub-stations are equipped with the following electrical protection :
MV side : one or mor e fuses whose r ating is/ar e deter mined accor ding to the char acter istics of the step
down transformer.
However this protection will only be installed when there are several TIT/LV sub-stations linked to a step up
station, because otherwise it is impossible to ensure selectivity with the step up transformer’s TIT protection.
LV side : The LV circuit breaker whose rating must be greater than the working current of the supplied power
receivers.
In the transformer : thermal probes connected to the LV circuit breaker.
THE LV SUB-NETWORK
Its layout depends on the terrain’s characteristics, the road layout, the possibilities for underground crossings, the
locations of natural or man-made obstacles.
A ground scheme must be chosen in accordance with current legislation and the continuous operation
requirements. A certain number of rules will be defined as a result of this choice.
These rules will determine whether or not it is necessary to install differential protection or insulation monitoring
devices on the step down station, and to determine the cross-section of the LV cables, called LV feeder s.
These rules are defined in a general way in the standard NF C 15-100 and when appropriate also in specialized
standards such as C 17200 or the C 17-205 guide for public lighting.
They guarantee :
 Feeder protection against excess current
 Personnel protection against indirect contacts
5
Concerning short circuit protection, as described in standard NF C 15-100 (art. 435-1 and 533-3 comments), the LV
circuit breaker of the step down sub-station that ensures overcharge protection is also considered to provide short
circuit protection at the same time.
For road lighting installations, the C 17-205 practical guide nevertheless recommends that the minimum short-circuit
rule should be satisfied, and suggests possible reductions in the line cross-section without any additional protection
device.
The LV sub-network of a step down sub-station as we have designed it does not comprise any reduction in
cross-section, and so the case described in guide C 17-205 does not concern us.
Let us consider for a moment the possibility that a short-circuit is not detected by the magnetothermal tripping
device, therefore creating a continuous fault.
In such a case the thermal probe protection installed in our TIT/LV sub-stations is capable of eliminating the fault,
regardless of whether or not it is dangerous for the LV feeders.
Given these considerations, it is not necessary to satisfy the minimum short-circuit rule, concerning LV networks
supplied via TED type or compact type step down transformers.
THE TIT TRANSPORTATION NETWORK
The number of outputs, their layout :
They are determined according to the planned locations for the different TIT/LV substations, the possibilities
offered by the terrain for trench excavation, road crossings and civil engineering works.
As far as possible we will make every effort to achieve balanced outputs, and when appropriate we will consider the
possibility of looping-in 2 outputs together, for repair purposes.
Any given output can be implemented as a single antenna, or with T branches or in a cross.
The TIT transmission network obtained in this way can also be linear type, star, loop or meshed, or a combination of
these different types.
The general output characteristics :
The output phase system must be three phase, in order to power the three phase TIT/LV sub-stations.
In this case, the preferred TIT voltage will be 6600 V, 5500 V or 950 V.
It should be noted that single phase TIT/LV sub-stations can however be installed on this type of output. The
transformers corresponding to this configuration comprise a phase selector making it possible to balance the output
charge distribution on the three phases.
If the TIT/LV sub-stations are all single phase, the output can be single phase or three phase.
In most cases, the single phase solution with a preferential voltage of 3200 V or 950 V is the most economic and the
easiest to implement. However, when the outputs are of a considerable length, the three phase solution with single
phase TIT/LV sub-stations can be selected, to reduce line drop and generally satisfy all the rules stipulated in the
standards.
6
Earthing scheme :
The scheme will be chosen from the TNRC or TNRS schemes, that in general are the most suitable (defined in conformity with standard UTE D17 200). The neutral TIT is linked directly to ground at the installation origin.
When the outputs are single phase either scheme can be selected, and the only difference is that in the TNRC
scheme the TIT neutral is grounded at each TIT/LV substation, and in the TNRS scheme it is not.
If the outputs are three phase the ground scheme has to be TNRS, since the neutral is not distributed.
The earth connections must be made :
 Individual earth connections.
 Connection to a bare copper conductor with à minimum cross section of 25 mm² which serves as both the earth
connection and an equipotential link between the poles.
 Common earth point with the poles connected by insulated cables.
The second solution, the earth network for bonding the equipment earths comprises a bare copper conductor with a
minimum cross sectional area of 25 mm² buried directly in the ground corresponding to the TIT line, is the one we
recommend because it allows to obtain better resistance to earth values.
Since the 1st of October 2003, the NC C 17 200 standard imposes this second solution for road lighting.
The earthing circuit this way will enable to connect :
 The earth point of the TIT/LV transformer.
 The neutral of TIT winding in a generalised earth scheme (TNR-C).
 The safety grid in the transformer housing.
 One point of the low voltage.
 The conducting parts of any equipment that can be accessed at the same time as that of the road lighting
system.
For the substation, the earth connection must be a bare conductor 25 mm² made of copper buried at about 50 cm
from substation.
This conductor will be depth of about 40 cm, the iron framework of the station concrete pedestal being, in that case,
linked to this conductor.
The transformer neutral must be connected to the earth connection to realise a TN scheme.
The substation earth bonding must be connected to the earth connection :
 The earths of all circuits in the substation.
 The screens of the cable.
 The transformer tank.
 The switching devices.
 The metal pipework and ducting.
However, the doors of the building and the metal ventilation slots should not intentionally be bonded.
7
8
CALCULATION OF FEEDER CROSS SECTION :
This calculation will be determined by the maximum authorized voltage drop, by adding together the values from
the TIT and LV voltage drops. The total voltage drop must not exceed 6% for a road lighting installation, and 8%
in other cases.
However it will be necessary to check that the protection fuse located at the circuit origin (at the step up station)
makes it possible to satisfy the stipulated rules, i.e.:
 Protection against indirect contacts.
 Protection against over charges.
 Protection against excess current.
If necessary a differential relay can be installed, if a TNRS scheme is used, to make it easier to satisfy the rules
mentioned above.
9
THE SUBSTATION :
The substation will be step up or step down type.
Implementation :
As far as possible, the substation will be installed in the center of the installation. However, installation off-center
is perfectly acceptable when an TIT transmission voltage is used.
The implementation will be determined according to the possibilities for installation offered by the site.
Nominal Power :
Nominal power is determined by the sum of step-down sub-station powers, taking into account the extension
possibility or non-project and by retaining a standardized transformer power.
Step-up stations will be used for powers from 5 to 160 kVA for easy projects, with most often, only one TIT network departure.
Step-down stations will be used for powers from 160 to 1250 kVA which intensities are compatible with the circuit
breaking bearing of pluggable terminals of step-down watertight transformers.
For service continuity reasons, it is possible to retain a transformation station equipped with two identical power
transformers. One transformer supplies the whole installation in case of the failure of one of the transformers.
Coupling:
The type of step-up transformer coupling depends on which phase system is selected for the TIT outputs.
In the case of three phase outputs, it will be three phase.
In the case of single phase outputs, it can be three phase, three/two phase, three/single phase or single phase:
 Three phase can be selected if there are three outputs or a multiple of three. These outputs must be virtu-
ally balanced.
 Three/two phase will be selected if there are two outputs or a multiple of two. These outputs must be
virtually balanced.
 Three/single phase is the only coupling that corresponds to all the possible situations and that allows
looping of 2 outputs for repair. It implies that the primary currents will not be balanced.
TIT networks control :
For networks only composed with lamps, inputs will be temporary, off during the day, controlled by a photo
electrical cell doubled with an astronomical clock. The control will also be realizable by current carrier using the
STEP II system.
For networks supplying receivers different from lamps, inputs will be permanent.
For mixt networks, inputs will be permanent the lighting control will be made by current carrier.
Dimmer :
It is better to put, in the transformer station, a dimmer regulator to reduce the power of lamps during weak traffic
hours. The dimmer regulator allows, during hours when reduction happens, consumption savings.
10
TOOLS :
In the appendix, you will find all the documentation to help you with the realization of a quick TIT study :
Case of the supplying of receiver units at a line end :
 The guide for the choice of the voltage level transportation to supply the end of line load.
Case of the supplying of receivers uniformly spread, road lighting case :
 Annex : number of lamps for each TIT/LV lighting transformer.
 Choice of the LV cable section downstream of the step-down watertight transformer.
 Concrete prefab pits best dimensions for step-down transformers installation.
 Choice of the MV cable section for single-phase and three-phase networks, for a 2 or 3 % voltage drop.
 Choice of the MLV cable section for single-phase and three-phase networks, uniformly spread load at the end of
the line.
 Calculation formula enabling to control the choices with the annex usage and AUGIER.
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APPLICATION EXAMPLE :
SUPPLY FOR A ROAD LIGHTING « LV/TIT » INSTALLATION
PROJECT :
In the following section, by means of an example we show how to determine rapidly the main sections constituting
a preliminary study for a road lighting project using TIT transmission voltage.
We draw the reader’s attention to the need to check or further specify the results obtained using the method set out
below. This is because, apart from the approximate nature of this example, it is not intended to provide an answer
for every situation or for every special case that may arise.
The aim of the project we have used in this example is to define the power supply for road lighting of a road.
Determination of the basis for calculation :
The calculations are to be performed on the basis of the information to be supplied below :
 Number of power consumers and type







Installation of the lighting poles
Network length
Station location
Supplied voltage level
Installation conditions
Altitude less than 1000 meters
Internal installation
: the installation comprises one lighting pole every 35 m, each
fitted with two 250W high pressure sodium lamps.
: The lighting poles are set up in the central reservation.
: The total length of the installation is 4 km.
: The station is located in the middle of the installation.
: Three phase 400 V
: Maximum ambient temperature 40°C
Operating principle :
This substation will be supplied from a low voltage three phase 400 V power source, via the mains
network, and will transform this voltage into a transmission voltage to be determined.
STEP 1 : Determination of the network’s rating power :
Determination of number of the lamps :
The installation’s power is determined by the number and type of the lamps used, whose mean characteristics
are described in guide C 17 205.
Application :
Number of lamps : 230
Type and power : 250 W HPS
Determination of the road lighting transformers’ power :
Their power depends on the number of lamps powered by the network transformer.
The transformers are used in conformity with standard NFC 52-410, which limits their use to 0.8x NP where
NP is the nominal power.
12
As a rule we will use transformers with :




3 kVA in exchangers where the lamps will be distributed in all directions.
5 kVA for the current sections.
10 kVA for the pole power supplies.
Other power supplies available according to use.
The number of lamps supplied by a transformer is given in our table « Number of lamps by transformers TIT/LV »
LAMPS TYPE
HPS LAMPS
Power (W)
70
100
150
250
400
600
1000
2000
Power (VA)
104
138
196
322
506
713
1242
2310
TRANSFORMER POWER RATING
NUMBER OF LAMPS BY TRANSFORMER
Nominal power
400 VA
630 VA
1 kVA
2 kVA
3 kVA
Using power
320 VA
500 VA
0,8 kVA
1,6 kVA
2,4 kVA
3
5
8
16
24
2
3
5
11
17
1
2
4
8
12
1
1
2
5
7
1
1
3
4
1
2
3
1
2
1
5 kVA
4 kVA
40
29
20
12
8
5
3
1
10 kVA
8 kVA
25
16
11
6
3
Application :
5 kVA with a maximum of 12 lamps HPS 250 W
TIT NETWORK
Substation
TIT/LV 5 kVA
Substation
TIT/LV 5 kVA
35 m
12 x HPS 250 W
Determination of the network’s total power :
The total power depends on the number of network transformers
Application :
20 network step-down transformers 5 kVA, total power = 100 kVA.
STEP 2 : Determination of the low voltage cable cross-section :
In general, the TN ground scheme will be used.
The cable cross-section depends on :
 The length of the low voltage sub-network seen from the transformer side, for a transformer placed in the
middle.
 On the protector block rating (LV circuit breaker).
13
The cable section is shown in the « Low voltage cross section determination »
Maximum length (m) for one side of the transformer
Protected against indirect contacts with 1 extr. MALT
Rating power
(kVA)
4
6
Cross section (mm²)
10
16
25
0,4
552
774
1143
1561
2000
0,63
1
2
3
4
552
552
345
276
221
5
172
6
8
10
138
774
774
484
387
310
242
194
155
1143
1143
714
571
457
357
286
229
181
1561
1561
976
780
624
488
390
312
248
2000
2000
1250
1000
800
625
500
400
317
Application :
Length of the LV sub-network on one side of the transformer : 87.5 meters + 5 meters vertical section per pole.
Total length = 102.5 meters. The cable cross section is 2 x 4 mm².
TIT Network
Substaion TIT/LV
5 kVA
Substation TIT/LV
5 kVA
LV Câble 2x 4mm²
35 m
102,5m
12 x HPS 250 W
STEP 3 : Determination of the distribution type and level of transmission voltage :
The distribution may be :
 Three phase 5500 V for long charged networks, or networks that comprise three phase power receivers.
 Single phase 3200 V for power values up to 100 kVA, for installations that only have one output.
 Two phase 3200 V for power values up to 100 kVA, for installations with two balanced outputs (2 x 50 kVA).
Application :
The substation is placed in the center of the application with 50 kVA to supply on each side. Two phase 3200 V
distribution.
STEP 4 : Determination and selection of Road lighting Transformers :
The transformers are determined according to :
 The transformer coupling.
 The type of distribution network (single phase or three phase) .
 The type of cable used.
14
Application :
Single phase transformer for single phase network, using two pole concentric cable TER MM, TED MMX or
Modulo BI type.
Please refer to the transformer documentation available.
STEP 5 : Determination of the MV cable cross-section
The choice of cable cross-section depends on the power and length of the network.
The length is basically limited by the line drop.
Protection is ensured by choosing a protection.
The cross-section is given in appendix « MV cable cross section determination », which takes into account a
maximum MV line drop of 2%, compatible with the total limit of 6% for MV and LV.
Cross section (mm²)
Power Rating
(kVA)
6
10
16
25
30
1750
2890
4580
7260
40
1310
2170
3435
5445
50
1050
1735
2750
4355
60
875
1445
2290
3630
70
750
1240
1960
3110
80
655
1080
1720
2720
Application :
The 3200 V cable cross section for supply 50 kVA per output on the Length 2000 meters is 16 + 16 mm².
Two pole concentric cable 16 +16 mm²
Single phase network 3200 V
TED MMX 5 KVA
3200 V/230 V
TED MMX 5 KVA
3200 V/230 V
LV Cable 2x4 mm²
35 m
12 x HPS 250 W
Step 6 : Determination of the substation :
Determination of the substation power :
The main transformer’s power must be at least equal to the sum of the nominal powers of the road lighting
transformers, supplied downstream (NFC 17-200).
We will choose a standard power, chosen in the range : 25, 50, 63, 80, 100, 125, or 160 kVA
Application :
In order to have an extension possibility, the retained power is 125 kVA.
15
The substation will be equipped with :
 A LV counting table.
 A step-up set protection and control table.
 A power transformer, three-two phases, 400 V/3200 V with a 125 kVA power rating.
The different features that constitute the protection table are determined depending on the transformer’s
characteristics and dimensioned during the definitive study.
Conclusion :
This fore-study enables to difine the heights conforming to NFC 17-200 et NFC 52-410 standards with respect to a
global voltage drop of 6% maximum.
All the features of the fore-study, will have to be confirmed by a more precise calculation, in order to also precise and
confirm the values obtained.
Indeed, for our application, the 3200 V cable section retained would be 10+10 mm².
16
APPENDIX
17
NUMBER OF LAMPS FOR EACH TIT/LV NETWORK TRANSFORMER :
Determination of the maximum number of lamps to use depending on the transformers power, conforming to the
standard recommendations NFC 17-200, NFC 52-410 and C 17-205 guide.
TYPE OF LAMPS
HIGH PRESSURE SODIUM LAMPS
MERCURY LAMPS
Power Rating (W)
70
100
150
250
400
600 1000
2000
125
250
400
700
Power Rating (VA)
104
138
196
322
506
713 1242
2310
161
310
495
886
1
1
3
5
8
16
1
2
4
9
TRANSFORMER
POWER RATING
Nominal Power
Useful Load
400 VA
630 VA
1 KVA
2 KVA
3 KVA
5 KVA
10 KVA
320 VA
500 VA
0,8 kVA
1,6 kVA
2,4 kVA
4 kVA
8 kVA
NUMBER OF LAMPS PER TRANSFORMER
3
5
8
16
24
40
2
3
5
11
17
29
1
2
4
8
12
20
1
1
2
5
7
12
25
1
1
3
4
8
16
1
2
3
5
11
1
2
3
6
1
1
3
2
3
5
10
15
25
1
1
2
5
7
13
25
TYPE OF LAMPS
LOW PRESSURE SODIUM LAMPS
METALLIC IODIZED LAMPS
Power Rating (W)
26
35
55
91
131
250
400
1000
2000
Power Rating (VA)
37
51
78
113
152
322
506
1242
2369
1
2
3
6
1
1
3
TRANSFORMER
POWER RATING
P. Nominale
P. utile
400 VA
630 VA
1 KVA
2 KVA
3 KVA
5 KVA
10 KVA
320 VA
500 VA
0,8 kVA
1,6 kVA
2,4 kVA
4 kVA
8 kVA
NUMBER OF LAMPS PER TRANSFORMER
8
13
21
43
6
9
15
31
4
6
10
20
30
2
4
7
14
21
35
2
3
5
10
15
26
1
1
2
5
7
12
25
1
1
3
4
8
16
For information :
 Lamps lifespan is about 8 000 to 10 000 hours.
 The lighting functioning time, in France, is 4 085 hours.
18
DETERMINATION OF THE LOW VOLTAGE CABLE CROSS SECTION :
Single-phase network transformer
Maximum lengths in meters of the pipes, single-phase 230 V, TN scheme, with the windings edge linked to the
earth, protected against indirect contacts and overloads. Case of single-phase transformers protected by a circuitbreaker associated with a thermal probe.
Calculations established with a protection conductor of 1 x 25 mm².
Power
Rating
(kVA)
Intensity (A)
Under 230 V
Protection rating Low
voltage
Maximum length (m) one side of the transformer
Protected against indirect contacts with an earthing plug edge
Section (mm²)
4
6
10
16
25
0.4
1.74
C60 N - 10 A (B)
552
774
1143
1561
2000
0.63
2.74
C60 N - 10 A (B)
552
774
1143
1561
2000
1
4.35
C60 N - 10 A (B)
552
774
1143
1561
2000
2
8.70
C60 N - 16 A (B)
345
484
714
976
1250
3
13.04
C60 N - 20 A (B)
276
387
571
780
1000
4
17.39
C60 N - 25 A (B)
221
310
457
624
800
5
21.74
C60 N - 32 A (B)
172
242
357
488
625
6
26.09
C60 N - 40 A (B)
138
194
286
390
500
8
34.78
C60 N - 50 A (B)
155
229
312
400
10
43.48
C60 N - 63 A (B)
181
248
317
Non standard section
Maximum lengths (in meters) of single-phase pipes in scheme TN, protected against indirect contacts :
L = k U S / (R (1+m)Ind
With : k
U
S
R
m
Ind
= 0,8
= 230 V
= LV cable section
= 0,023
= S / 25
= 5 x circuit-breaker rating
Maximum lengths (in meters) of single-phase pipes in scheme TN, protected against circuit breakings :
In the case of transformers protected by a circuit-breaker associated to a thermal probe, rule not to be verified.
L = K U S / (2 Rcc ind)
With :
Rcc
Ind
K
= 0,8
= 0,023 (Protection by circuit-breaker)
= 5 x circuit-breaker rating
19
DIMENSIONS OF CONCRETE PITS
Depending on the existing pit, for TER, TED and MODULOBLOC
Transformer
Power
Rating
Dimensions (inside) concrete pits (mm)
L
l
H
Approx.
Weight (kg)
Models
TED MMX
Modulobloc bi or tri
0,4 à 6 kVA
jusqu’à 6 kVA
800
800
887
900
EP 80
TER MM ou MT
TED MMX
TED MTT
Modulobloc bi or tri
1 à 10 kVA
8 et 10 kVA
2 à 10 kVA
8 et 10 kVA
1000
800
887
1100
EP 100
Every TED type
With elbow terminals
or modulobloc
16 à 32
kVA
1790
880
1200
3000
L5T
INDICATIVE DIMENSIONS OF CONCRETE PITS
Minimum dimensions (with a 3x25 mm² cable) for TED > 10 kVA and TEH
Transformer
Concrete pits dimensions (mm)
Power
Rating
L
W
H (b. straight)
H (b. elbowed)
1300
750
1300
1050
1450
800
1350
1150
1700
900
1500
1300
TED MMX
16 kVA
TED TTT
5 - 10 kVA
TED MMX
25 kVA
TED MTT
16 - 25 kVA
TED TTT
16 kVA
TED MMX
25 kVA
TED MTT
50 kVA
TED TTT
25 - 32 kVA
TEH TTT
50 kVA
1700
900
1600
1400
TEH TTT
80 - 100 kVA
1900
1000
1700
1500
20
DETERMINATION OF THE MV CABLE CROSS SECTION
3200 V single-phase network
 Compatible with a 2 % voltage drop :
Uniformly spread power rating, maximum network departure lengths in meters.
6
Power Rating
(kVA)
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
3.9
2626
1750
1313
1050
875
750
656
583
525
477
438
404
Cross Section (mm²)
10
16
Impedance at 85 °C
2.36
1.49
4339
6872
2893
4582
2169
3436
1736
2749
1446
2291
1240
1964
1085
1718
964
1527
868
1374
789
1250
723
1145
668
1057
620
982
579
916
542
859
510
809
482
764
457
723
434
687
655
625
598
573
25
0.94
10894
7262
5447
4357
3631
3112
2723
2421
2179
1981
1816
1676
1556
1452
1362
1282
1210
1147
1089
1037
990
947
908
 Compatible with a 3 % voltage drop :
Uniformly spread power rating, maximum network departure lengths in meters.
Power Rating
kVA
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
6
3938
2626
1969
1575
1313
1125
985
875
788
716
656
606
563
525
492
463
438
415
Cross Section (mm²)
10
16
6508
10309
4339
6872
3254
5154
2603
4123
2169
3436
1860
2945
1627
2577
1446
2291
1302
2062
1183
1874
1085
1718
1001
1586
930
1473
868
1374
814
1289
766
1213
723
1145
685
1085
651
1031
620
982
592
937
566
896
542
859
25
16340
10894
8170
6536
5447
4669
4085
3631
3268
2971
2723
2514
2334
2179
2043
1922
1816
1720
1634
1556
1485
1421
1362
21
 Compatible with a 4 % voltage drop :
Uniformly spread power rating, maximum input lengths in meters.
Power Rating
(kVA)
6
3.9
5251
3501
2626
2101
1750
1500
1313
1167
1050
955
875
808
750
700
656
618
583
553
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
Cross Section (mm²)
10
16
Impedance at 85 °C
2.36
1.49
8678
13745
5785
9163
4339
6872
3471
5498
2893
4582
2479
3927
2169
3436
1928
3054
1736
2749
1578
2499
1446
2291
1335
2115
1240
1964
1157
1833
1085
1718
1021
1617
964
1527
913
1447
868
1374
826
1309
789
1250
755
1195
723
1145
25
0.94
21787
14525
10894
8715
7262
6225
5447
4842
4357
3961
3631
3352
3112
2905
2723
2563
2421
2293
2179
2075
1981
1895
1816
 Three-phase 5500 V network, compatible with a 2% voltage drop
Power Rating
(kVA)
50
100
120
140
160
180
200
220
240
260
280
300
320
340
360
380
400
420
440
460
480
500
630
6
10
3.9
6205
3103
2585
2216
1939
1724
1551
1410
1293
1193
1108
1034
2.36
10254
5127
4273
3662
3204
2848
2564
2331
2136
1972
1831
1709
1602
1508
1424
1349
1282
1221
1165
1115
Cross Section (mm²)
16
25
Impedance at 85 °C
1.49
0.94
16242
25745
8121
12872
6767
10727
5801
9195
5076
8045
4512
7151
4060
6436
3691
5851
3384
5363
3123
4951
2900
4597
2707
4291
2538
4023
2388
3786
2256
3576
2137
3387
2030
3218
1934
3065
1846
2926
1765
2798
1692
2682
1624
2574
1289
2043
35
50
0.66
0.46
18333
15278
13095
11458
10185
9167
8333
7639
7051
6548
6111
5729
5392
5093
4825
4583
4365
4167
3986
3819
3667
2910
26304
21920
18789
16440
14614
13152
11957
10960
10117
9394
8768
8220
7737
7307
6922
6576
6263
5978
5718
5480
5261
4175
22
 Three-phase 5500 V network, compatible with a 3% voltage drop
6
10
3,9
9308
4654
3878
3324
2909
2585
2327
2115
1939
1790
1662
1551
1454
1369
1293
1225
1163
1108
1058
2,36
15381
7691
6409
5493
4807
4273
3845
3496
3204
2958
2747
2564
2403
2262
2136
2024
1923
1831
1748
1672
1602
1538
1221
Power Rating
(kVA)
50
100
120
140
160
180
200
220
240
260
280
300
320
340
360
380
400
420
440
460
480
500
630
Cross Section (mm²)
16
25
Impedance at 85 °C
1,49
0,94
24362
38617
12181
19309
10151
16090
8701
13792
7613
12068
6767
10727
6091
9654
5537
8777
5076
8045
4685
7426
4350
6896
4060
6436
3807
6034
3583
5679
3384
5363
3206
5081
3045
4827
2900
4597
2768
4388
2648
4198
2538
4023
2436
3862
1934
3065
35
50
0,66
0,46
22917
19643
17188
15278
13750
12500
11458
10577
9821
9167
8594
8088
7639
7237
6875
6548
6250
5978
5729
5500
4365
32880
28183
24660
21920
19728
17935
16440
15176
14092
13152
12330
11605
10960
10383
9864
9394
8967
8578
8220
7891
6263
35
50
0,66
0,46
30556
26190
22917
20370
18333
16667
15278
14103
13095
12222
11458
10784
10185
9649
9167
8730
8333
7971
7639
7333
5820
32880
29227
26304
23913
21920
20234
18789
17536
16440
15473
14614
13844
13152
12526
11957
11437
10960
10522
8351
 Three-phase 5500 V network, compatible with a 4% voltage drop
Power Rating
(kVA)
50
100
120
140
160
180
200
220
240
260
280
300
320
340
360
380
400
420
440
460
480
500
630
6
10
3,9
12410
6205
5171
4432
3878
3447
3103
2821
2585
2387
2216
2068
1939
1825
1724
1633
1551
1477
1410
2,36
20508
10254
8545
7324
6409
5697
5127
4661
4273
3944
3662
3418
3204
3016
2848
2698
2564
2441
2331
2229
2136
2051
1628
Cross Section (mm²)
16
25
Impedance at 85 °C
1,49
0,94
32483
51489
16242
25745
13535
21454
11601
18389
10151
16090
9023
14303
8121
12872
7383
11702
6767
10727
6247
9902
5801
9195
5414
8582
5076
8045
4777
7572
4512
7151
4274
6775
4060
6436
3867
6130
3691
5851
3531
5597
3384
5363
3248
5149
2578
4086
23
LV AND MV CABLES APPEARING IMPEDANCE
MV cables :
Table valid for concentric bipolar and tripolar cables.
Given values for cables calculated at an average temperature of 50 °C.
Cross Section (mm²)
Impedance ( / km)
6
3.41
10
2.03
16
1.28
25
0.81
35
50
0.58
0.41
LV Cables :
Table valid for armed LV bipolar and tripolar cables.
Given values for cables calculated at an average temperature of 65 °C.
Cross Section (mm²)
Impedance ( / km)
4
4.4
6
2.96
10
1.78
16
1.15
25
0.743
35
0.551
50
70
0.421
0.309
24
VOLTAGE DROP CALCULATION
1/ LV Side Voltage Drop : ULV
1/a) LV Single Phase Network :
ULV = 2 L i (n (n + 1) / 2) Z
ULV % = U / 230 (V)
i (A)
:
L (km)
:
n
:
Z ( / km) :
rated current of one pole i.e. = P(VA) * q / 230 (V) with q : number of lamps per pole
and P : power of one lamp
inter-distance length between each lighting pole, plus 5 meters cable to reach the pole.
Number of poles on the side of the network transformer.
LV cable impedance.
1/b) LV Three-phase Network :
ULV = 3 L3 (i*3) (n3 (n3 + 1 ) / 2) Z
ULV % = U / 400 (V)
i (A) :
L3
n3
:
:
Rated current of one pole i.e. = P (VA) * q / 230 (V) with q : number of lamps per pole
and P : power of one lamp.
Inter-distance between groups of three poles => for example l3 = 3*L + 0,005.
Number of poles in group of three.
25
2/ MV Network Voltage Drop : Umv
2/a) TER or TED Type transformers (MV/LV) are regularly distributed in the network
A-TER MM or TED MMX :
Umv =  L I (n(n+1)/2) Z
Umv %= Umv / 3200 (V)
I(A)
:
L (km)
:
n
:
Z (Ω / km) :
Intensity for a transformer calculated on its nominal power in kVA : I=P / 3200 (V).
Interdistance between each transformer.
Number of transformer.
MV cable impedance.
B– TER MT or TED MTT :
Umv = 3 (3 * L) (3 * I) (n3 (n3 + 1) / 2) Z
Umv %= Umv / 5500 (V)
I (A)
L (km)
n3
Z ( / km)
:
:
:
:
Current of one transformer according to P (VA) calculated as I = P / 5500 (V).
Inter-distance length between each transformer.
Number of transformers in group of 3.
IHV cable impedance.
C– TER TT or TED TTT :
Umv = 3 L I (n (n + 1) / 2) Z
Umv %= Umv / 5500 (V)
I (A)
L (km)
n
Z ( / km)
:
:
:
:
Current of one transformer according to P(VA) calculated as : I = P / (5500 * 3).
Inter-distance length between each transformer.
Number of transformers.
MV cable impedance.
2/b) Deliver of power to a distance of L (km) three-phase network :
Umv = 3 L I Z
Umv % = Umv / 5500 (V)
I (A)
:
Z ( / km) :
L (km)
:
Current of the network I = P / (5500*  3).
MV cable impedance.
Distance between the supplier and the receiver.
Please note :
The power rating mentioned is the sum of the network transformers power rating. In the case of the
network transformers load is reduced , we can use the sum of the power rating of the supplied lamps
counting a coefficient of around 15 %.
26
Way of using the power supply range graph.
These graphs help you to find quickly the right solution for the supply of a single load.
The graph inputs are the distances of the load and its power.
With these parameters, you obtain the voltage level to use and the wire section.
Example :
We have several receptors to supply at 3480 meters far. Their power are respectively 10,20,30 and 50 kVA.
You have to report on the graph the cross between the 10 kVA line and the 3480 meters line. It is in the area for
mono 3200V with a wire section of 6 mm². This is the best solution. You can also notice that it is under the
non-continuous line for mono 950V 35mm² wire section. It means this solution is technically working but
economically less profitable than medium voltage. It will be use only if we absolutely want to use low voltage. As
for the 20 kVA receptors, the only solution is 3200V wire section 6 mm². Then for 30 kVA, we use 10 mm² as wire
section and 16 mm² for the 50 kVA receiver.
Comment on the graphs.




The drawing represent the technical limit for each kind of solution to respect a maximal voltage drop of %.
All the area under the drawing respect this condition.
The colored areas correspond to domain were the use of a solution is the more accurate.
For distance shorter than 500m the graph are not valid.
The non-continuous drawing represent the limit for a technically working solution but not profitable.
27
End of line single-phase loads
28
End of line three-phase loads
29
DETERMINATION OF THE 950 V CABLE SECTION
950 V single-phase network uniformly spread power :
 Compatible with a 2% voltage drop :
Maximum input length in meters.
Length (m)
Power Rating
(kVA)
10
16
25
32
50
63
80
100
Cross Section
(mm²)
Z (85°)
I(A)
10,53
16,84
26,32
33,68
52,63
66,32
84,21
105,26
6
10
16
25
35
3,19
1,919
1,24
0,8
0,595
566
354
226
177
113
90
71
57
941
588
376
294
188
149
118
94
1456
910
582
455
291
231
182
146
2256
1410
903
705
451
358
282
226
3034
1896
1213
948
607
482
379
303
 Compatible with a 3% voltage drop :
Maximum input length in meters.
Length (m)
Power Rating
(kVA)
10
16
25
32
50
63
80
100
Cross Section
(mm²)
Z (85°)
6
10
16
25
35
3,19
1,919
1,24
0,8
0,595
I(A)
10,53
16,84
26,32
33,68
52,63
66,32
84,21
105,26
849
530
339
265
170
135
106
85
1411
882
564
441
282
224
176
141
2183
1365
873
682
437
347
273
218
3384
2115
1354
1058
677
537
423
338
4550
2844
1820
1422
910
722
569
455
 Compatible with a 4% voltage drop :
Maximum input length in meters.
Length (m)
Power Rating Cross Section
(mm²)
(kVA)
Z (85°)
I(A)
10,53
10
16,84
16
26,32
25
33,68
32
52,63
50
66,32
63
84,21
80
105,26
100
6
10
16
25
35
3,19
1,919
1,24
0,8
0,595
1132
707
453
354
226
180
141
113
1881
1176
752
588
376
299
235
188
2911
1820
1165
910
582
462
364
291
4513
2820
1805
1410
903
716
564
451
6067
3792
2427
1896
1213
963
758
607
30
950 V three-phase network uniformly spread power :
 Compatible with a 2% voltage drop :
Maximum input length in meters.
Length (m)
Power Rating
(kVA)
10
16
25
32
50
63
80
100
Cross Section
(mm²)
Z (85°)
I (A)
6,08
9,72
15,19
19,45
30,39
38,29
48,62
60,78
6
10
16
25
35
3,19
1,919
1,24
0,8
0,595
1132
707
453
354
226
180
141
113
1881
1176
752
588
376
299
235
188
2911
1820
1165
910
582
462
364
291
4513
2820
1805
1410
903
716
564
451
6067
3792
2427
1896
1213
963
758
607
 Compatible with a 3% voltage drop :
Maximum input length in meters.
Length (m)
Power Rating Cross Section
(mm²)
(kVA)
Z (85°)
I (A)
10
6,08
16
9,72
25
15,19
32
19,45
50
30,39
63
38,29
80
48,62
100
60,78
6
10
16
25
35
3,19
1,919
1,24
0,8
0,595
1697
1061
679
530
339
269
212
170
2822
1764
1129
882
564
448
353
282
4367
2729
1747
1365
873
693
546
437
6769
4230
2708
2115
1354
1074
846
677
9101
5688
3640
2844
1820
1445
1138
910
 Compatible with a 4% voltage drop :
Maximum input length in meters.
Length (m)
Power Rating
(kVA)
10
16
25
32
50
63
80
100
Cross Section
(mm²)
Z (85°)
I (A)
6,08
9,72
15,19
19,45
30,39
38,29
48,62
60,78
6
10
16
25
35
3,19
1,919
1,24
0,8
0,595
2263
1415
905
707
453
359
283
226
3762
2351
1505
1176
752
597
470
376
5823
3639
2329
1820
1165
924
728
582
9025
5641
3610
2820
1805
1433
1128
903
12134
7584
4854
3792
2427
1926
1517
1213
31
End of line 950 V single-phase network load :
 Compatible with a 3% voltage drop :
Maximum input lengths in meters :
Length (m)
Power Rating
(kVA)
Cross Section
(mm²)
Z (85°)
I(A)
6
10
16
25
35
3,19
1,919
1,24
0,8
0,595
5
5,26
849
1411
2183
3384
4550
10
10,53
424
705
1092
1692
2275
16
16,84
265
441
682
1058
1422
25
26,32
170
282
437
677
910
32
33,68
133
220
341
529
711
50
52,63
85
141
218
338
455
63
66,32
67
112
173
269
361
80
84,21
53
88
136
212
284
100
105,26
42
71
109
169
228
 Compatible with a 4% voltage drop :
Maximum input lengths in meters :
Length (m)
Power Rating
(kVA)
5
10
16
25
32
50
63
80
100
Cross Section
(mm²)
Z (85°)
I(A)
5,26
10,53
16,84
26,32
33,68
52,63
66,32
84,21
105,26
6
10
16
25
35
3,19
1,919
1,24
0,8
0,595
1132
566
354
226
177
113
90
71
57
1881
941
588
376
294
188
149
118
94
2911
1456
910
582
455
291
231
182
146
4513
2256
1410
903
705
451
358
282
226
6067
3034
1896
1213
948
607
482
379
303
 Compatible with a 5% voltage drop :
Maximum input lengths in meters :
Length (m)
Power Rating
(kVA)
5
10
16
25
32
50
63
80
100
Cross Section
(mm²)
Z (85°)
I(A)
5,26
10,53
16,84
26,32
33,68
52,63
66,32
84,21
105,26
6
10
16
25
35
3,19
1,919
1,24
0,8
0,595
1415
707
442
283
221
141
112
88
71
2351
1176
735
470
367
235
187
147
118
3639
1820
1137
728
569
364
289
227
182
5641
2820
1763
1128
881
564
448
353
282
7584
3792
2370
1517
1185
758
602
474
379
32
End of line 950 V three-phase network load :
 Compatible with a 3% voltage drop :
Maximum input lengths in meters :
Length (m)
Power Rating
(kVA)
Cross Section
(mm²)
Z (85°)
6
10
16
25
35
3,19
1,919
1,24
0,8
0,595
1697
849
530
339
265
170
135
106
85
2822
1411
882
564
441
282
224
176
141
4367
2183
1365
873
682
437
347
273
218
6769
3384
2115
1354
1058
677
537
423
338
9101
4550
2844
1820
1422
910
722
569
455
I (A)
5
10
16
25
32
50
63
80
100
3,04
6,08
9,72
15,19
19,45
30,39
38,29
48,62
60,78
 Compatible with a 4% voltage drop :
Maximum input lengths in meters :
Length (m)
Power Rating
(kVA)
Cross Section
(mm²)
Z (85°)
6
10
16
25
35
3,19
1,919
1,24
0,8
0,595
2263
1132
707
453
354
226
180
141
113
3762
1881
1176
752
588
376
299
235
188
5823
2911
1820
1165
910
582
462
364
291
9025
4513
2820
1805
1410
903
716
564
451
12134
6067
3792
2427
1896
1213
963
758
607
I (A)
5
10
16
25
32
50
63
80
100
3,04
6,08
9,72
15,19
19,45
30,39
38,29
48,62
60,78
 Compatible with a 5% voltage drop :
Maximum input lengths in meters :
Length (m)
Power Rating
(kVA)
Cross Section
(mm²)
Z (85°)
6
10
16
25
35
3,19
1,919
1,24
0,8
0,595
I (A)
5
3,04
2829
4703
7278
11281
15168
10
6,08
1415
2351
3639
5641
7584
16
9,72
884
1470
2274
3525
4740
25
15,19
566
941
1456
2256
3034
32
19,45
442
735
1137
1763
2370
50
30,39
283
470
728
1128
1517
63
38,29
225
373
578
895
1204
80
48,62
177
294
455
705
948
100
60,78
141
235
364
564
758
33
PERSONAL NOTES
34
PERSONAL NOTES
35
60 10062 With constant improvements, the manufacturer may alter information without prior warning
AUGIER IS CERTIFIED ISO 9001 SINCE 1995
36