SYSTEM OF TRANSPORT AND DISTRIBUTION OF ENERGY TO VOLTAGE INCLUSIVE BETWEEN 600V AND 1200V

Abstract: A system of transport, distribution and/or sale of electric energy to industrial frequency to inclusive voltage between 600V and 1200V essentially constituted by normalized cables for lines to low voltage, three-phase transformers with two BT voltage in delivery and circuit breakers. The system is characterized by the fact to transform the electric voltage from medium voltage (3000.30000V) to a level of voltage understood between 600V and 1200V through three-phase transformers MT/B1T1 of power 50, 100 or 160 kVA or about, to transport with normalized cable of low voltage, aerial or underground, or with other fit mean till to a near place to the utilization where the voltage suffers a second transformation to the level of voltage in use, generally 400/231 or 220/127 Volts and till 110V.

Description: Description SYSTEM OF TRANSPORT AND DISTRIBUTION OF ENERGY TO VOLTAGE INCLUSIVE BETWEEN 600V AND 1200V Technical field Object of the present invention is to realize a system of transport, distribution and/or sale of electric energy to industrial frequency to inclusive voltage between 600V and 1200V essentially constituted by normalized cables for lines to low voltage, three-phase transformers with two BT voltage in delivery and circuit breakers. State of the technique In much areas, the principal problem of the distribution and the delivery of electric energy is to contain the tension drop in compatible limits with the prescriptions of the electric norm and the contractual clauses. The actual state of the art foresees that the transport, the distribution, the delivery and the sale of electric energy to the customers to the voltage 400/231 V and till 110V is directly gotten by the system to medium voltage (3000÷30000V) without other intermediate passage. Opportune static machines (transformers) distributed on the territory in relationship to the density of the load, transform the electric voltage from medium voltage (that we point out with MT) to low voltage (that we point out with BT) and therefore ready to be used for the most varied uses. It is known that the scarce quality of the electric service, especially in the areas to low density of load and in rural areas, is mainly owed to the line of medium voltage: the number of interruptions transitory and short and big part of those long, as well as good part of the holes of tension, almost exclusively depends on the extension of the MT line, more exposed to the atmospheric troubles and with a number of users, contemporarily involved by a breakdown of the service, decidedly superior to what is realized in a single BT line. Purpose of the present invention is to propose a new level of voltage superior to the existing 400V for better make front the new demands, to contain the costs of investment for the lacing of customers of low power placed in areas to low density of load, to improve the quality of the service in the rural areas, characterized by long MT aerial lines, to reduce the times of realization of the lacing and to reduce the visual impact of the installations. Other purpose of the present invention in accord with the preceding understanding is that to contain the extension of the MT line, that is of that MT line subtended by the single support and of conseguence of that subtended by a whole bar of primary box replacing with a BT line more elevated of that standard contractual to the users, in how much this last has a modest ray of action because of limits in the voltage drop. Other purpose of the present invention in accord with the preceding understanding is that to allow the lacing of customers, that need increases of electric power of the supplies (that they are to the limit for voltage drop) but that at the same time they want to avoid to pass to the MT both for economic motives and for the simplification of the release of authorizations or permissions. Other purpose of the present invention in accord with the preceding understanding is that to use for the transport, the distribution and the delivery of the electric energy a new level of tension understood between 600V and 1200V (that we point out with that preferably uses the BT normalized cables in use in such way to get a great economic convenience of the distribution of electric energy and with small environmental problems in substitution or placed side by side to the medium voltage lines, very more expensive and often less reliable than those to low tension in cable. Other purpose of the present invention, according to the preceding understanding, it is that to realize a system of electric current supply to an voltage inclusive between 600V and 1200V through the use of transformers to eventually two deliverings to the secondary one. Description of the drawings and modes for earring out the invention The invention is exposed more precisely with examples exemplified of forms of preferred realization accordingly to the attached drawings and furnished to only indicative purpose and not limitative in which: - the fig.1 schematically shows the state of the art; - the fig. 2 schematically shows a first form preferred of realization of the system object of the present invention; - the fig. 3 schematically shows a second form of the system of preferred realization of the present invention; - the fig. 4 schematically shows a further form preferred of realization of the present invention. - The fig.5 shows the comparison among the transportable power with the two levels of voltage in function of the length of the line and to parity of voltage drop (5%). - The fig.6 shows the nomenclature of the graphic signs . The attached figures shows the typical schemes of application of the present invention that can be different in function of the limiting factor of the voltage drop and the load to supply. As it can be noticed by the drawings attached for resolving all the cases that are introduced in the technical practice, are necessary further that the interrupters (or circuit breakers) on purpose realized for the B 1 T 1 lines three typologies of transformers or autotransformers of suitable powers and with the following tensions: a) Three-phase Transformers MT / B 1 T 1 /BT (power nominal 160 , 250 KVA or around) with the primary to 3000÷30.000V and the secondary two voltage: B 1 T1 of 600÷1200V and the other BT of 400/231 V or 231 /127V and till 110V. The transformer MT/ B- 1 T 1 /BT finds employment both for the departure from boxes in masonry both for those from pole. In the first case is had the maintenance of the only MT dorsal eliminating the derivations in MT and foreseeing boxes of transformation along the said dorsal with transformations toward the 400V local and toward the 600-1200V to realize radial lines with a ray of action of the order of some kilometres according to the transported power and of the section of the cable. In the second case is had the insertion of a place of transformation from pole, supplied by a derivation on the dorsal MT (whose length is inferior however in comparison to the traditional solutions) from which to develop the system to 600-1200V in function of the load to supply. The level of voltage of 400/231 V or 220/127V supplies, according to the traditional canons, the users that, medially, they are distant to not more than 600/700 meters from the point of transformation MT/BT (box). The second level of voltage, that is that of 600÷1200V supplies loads that, to parity of power, can be around seven more distant times of those fed to 400/231 V. The middle distances will pass so to 3000÷4000 meters in comparison to those actual of 600/700 meters (as is schematically represented in fig.2). Must be noticed besides that, to parity of distance, the tension of 600÷1200V can feed loads, medially, six times great of those supplied to 400V. In the immediate proximities of the points of use, the presence of a second transformer kneels voltage of the electric energy from 600÷1200V to the value BT currently in use. b) Three-phase Transformers MT/ B1T 1 but of inferior power (50, 100, 160 KVA or around) to install on pole in the case of feeding with derivation direct MT from back; these transformers put to the disposition the voltage of 600÷1200V for the supplying only loads distant from the point of transformation. In proximity of the users a lowering voltage is operated from the voltage B1T1 to that BT, as schematically visualized in the fig. 4. c) Final Transformers B 1 T 1 /BT of small power ( 50KVA about) for the transformations on pole in proximity of the users; this transformer can work both to raise both to lower the tension, according to the scheme of fig.3; the transformer B-iT- f /BT has a low rate of breakdown because not subject over voltages of external origin. Remarkable is the fact that the transformers are entirely similar for the others characters nominal and constructive to those currently unified, so also the cables BT used by a lot of distributing societies of electric energy are already fit to be managed to the nominal tension of 600÷1 00V. Particularly the use of BT cables involves remarkable advantages: - the introduction of the cable managed to 600÷1200V increases the flexibility of the BT lines to 400/231 V existing or to build; these last ones can be foreseen till values of powers to the limit of their electric performances because an request of great power can be resolved simply passing the tension of exercise of the cable BT from 400V to 600÷1200V, avoiding expensive solutions to medium voltage; - about 50% of the BT cable to 600÷1200V can be put in work on the supports of the MT aerial lines interested by remaking; - the BT cable managed to 600÷1200V requires small appointment for the programmed inspection, often enough that occasional; - the BT cable managed to 600÷1200V requires a small ordinary maintenance in comparison to the MT aerial lines; - the line B1T 1 with covered cable has an environmental impact of big long inferior to that of the MT in naked conductors; - the line B 1 T 1 in aerial cable requires small appointment to the goals of the authorizations and the layout of the project in comparison to the MT line in naked conductors; - the BT aerial cable doesn't have bursts, possible holes of tension are negligible or enough contained; - the BT cable managed to 600÷1200V is few or nothing influenced by the atmospheric discharges; - the BT cable managed to 600÷1200V contains the current of breakdown toward earth on the MT line. What example we quote two cables, one for the aerial laying and the other for the laying in underground, very used for the transport of electric energy in low voltage. We repeat, very important thing, these two BT cables, without additional burden, they are already fit to be managed to the maximum tension of 1200V. The two types of cable are: 1 ) BT aerial cable ARE4RX with conductor of phase in aluminium from 70 or 35 mm 2 and neutral conductor from 54,6 mm 2 in league with good mechanical qualities; 2) BT cable G20CR/R in copper for buried laying; the sections of this type of cable, to neutral concentric, they embrace a wide range, from the 6 mm 2 till the 150 mm 2 and over. To parity of every other parameter, transport capacity of a line depends on the square of its nominal tension. Sets equal to 1 the transport capacity of the lines to 380V (C 0 .3 8k v) it is had: A line to 20 kV has an transport capacity 2.770 times superior to that to 380V. To the two levels of voltage correspond steps of powers very outdistanced; the MT lines cover a band of very ample power with the result that more than few times are used only for a small fraction of their potentiality. The introduction of an intermediate voltage, for example of 1000V would for instance bring the step of C-ikv = 6,93, filling the difference among 1 and 2.770. We would have the three steps: Ci.ok = 6,93 ; Chart n. 1 principal parameters of the covered cable ARE4RX The transport capacity of the BT cable has been calculated assuming a voltage drop not superior voltage to 5% of that nominal, for every kilometer of line and for every kW of power with cosφ = 0,8. In the hypothesis of which above, the transport capacity of the BT aerial cable in Al. 70mm 2 managed to 1000V is given from: P x L = 50 / (V3 x 0,46 x 0,72) = 87,26 kW x km, the same cable managed to 380 V has an transport capacity of 12,57 kW x km, equal to 6,94 times small of that managed to 1000V. With 5% voltage drop and cosφ = 0,8, the BT cable G20CR/R Cu 3x150+95C mm 2 managed to 1000V, has an transport capacity of 318 kW x km, able to also feed big supplies distant from the transformation point. To keep track of the voltage drop inside to the transformer or to the autotransformer, the transport capacity of the BT cable to 1000V must adequately be decreased in comparison to the values of the table 2. The voltage drop inside to the transformer can be calculated with the formula: -senip • costp 2 ; Δv% = voltage drop inside tension to the transformer, in percentage of that nominal; v cc % = value percentage of the voltage of short circuit of the transformer related to the current of full load; for currents minor of the full load, the value of it is reduced in proportion; cosφ = factor of power of the load fed by the transformer; cosφ cc = factor of power of short circuit of the transformer. The transformers of the distribution, medially work about 60% of their power ; for the areas with low density of load, particular cases excepted, the utilization of the transformers descended to values that go from 15 to 30% of their nominal power. The tension of short circuit of the MT/BT transformers of the distribution (v cc %) it is around 4% of that nominal; less than 2% for the B 1 T 1 /BT transformers and the MT/B^/BT transformers side MT/ B 1 T 1 . The factor of power of the load (cosφ) can be assumed equal to 0,8; that of short circuit (cosφ cc ) it is equal, approximately, 0,2 for the transformers, and 0,1 for the B 1 T 1 /BT transformers and the MT/ B-iT^BT transformers side MT / BITL Example 1. Autotransformer that supplies a power equal to 30% of that of plate with cosφ equal to 0,8: Δv% = 0,3(2*(0,8*0,1+0,6*0,99)+4/200 * (0,8*0,99-0,6*0,1) 2 = (0,40 + 0,003)% = 0,40% of that nominal. The second term of the formula of the voltage drop is, generally, negligible compared to the first one. Example 2. Transformer that supplies a power equal to 30% of that of plate equal to 0,8: Δv% = 0,3(4*(0,8*0,2+0,6*0,98+16/200*(0,8*0,98-0,6 * 0,2) 2 = (0,90 + 0,011 )% inferior to 1 % of that nominal. The presence of the transformers therefore it doesn't alter brings to the thermal limit of the cable to 1000V; while his transport capacity with voltage drop to 5%, it decreases of an enough contained quantity. The graph of fig. 5 put in evidence the fact that the new level of tension of 600/1200V (in the example 1000V) it replaces, mainly, the medium voltage whose lines are a little reliable and very more expensive of those to low voltage. Remarkable advantages are had following the adoption of the present invention; in fact the electric fittings of the distributing societies are modified radically, particularly: a) the length of the MT aerial lines naked decreases, middly, of 30%; b) the number of the PTP (places of transformation from pole) decreases of over 80%. The transformers to two secondary ratio MT / B 1 T 1 /BT will be installed in the boxes in masonry and on the PTP; c) the number of the boxes in masonry MT/BT of thirds (not of the distributing societies) decreases of 50%; d) the number of the nodal boxes (boxes for the automatic selection of the breakdown) it decreases of around 30%; e) the length of the lines of low voltage increases of 25%. For about half of the B 1 T 1 lines (600÷1200V) to build, can be used the supports of the MT lines destined to be declassed to 600÷1200V; f) for every group of customers and more rarely for every customer, a B-iT-]/ transformer or BT autontrasformer is required . The other principals advantages are: the adoption of the voltage to 600÷1200V makes to decrease the number of the expensive primary boxes AT/MT; the introduction of the level of voltage to 600÷1200V makes possible the sale of the electric energy to voltage of 600÷1200V with mutual advantage of the distributor and the users; the BT cable managed to 600÷1200V therefore it will especially improve the quality of the electric service in as suburban and rural areas, to such a level that to get it in other way investments would be necessary of big long superior; in fact to the actual state in the rural and suburban areas, one of the solutions more followed by the distributing society to improve the quality of the electric service is that to transform the actual MT aerial lines, from rigid to suspended with the substitution of the conductors and the realization of a MT line to connections and nodal boxes with a remarkable economic appointment for every kilometre of MT line interested in the remaking. Instead the present invention leaves the MT connections unchanged, while declassing to 600÷1200V the actual MT aerial derivations that transport powers of the order of 100 kW, resolving so the problem of the technique note. The introduction of the level of tension of 600÷1200V brings advantages, not only to the distributing societies of electric energy, but also to the new customers to be laced that they require a busy power around the 100/160 kW and distant from a MT/BT transformation box of around 200/600 meters. The solution to the actual state of the technique foresees to load of the users the construction of a box in masonry or a prefabricated, complete of equipment with a MT/BT transformer of the power of 250 kVA and eventually a second transformer of ready reserve and relative equipment; to load, instead, of the distributing society are the dissection and measure equipments of the electric energy and the construction of the link of MT line between the existing line and the box of the customer. The system of transport, distribution e/o delivers of electric energy of the present invention, utilizing a cable or other mean of transport to 6O0÷1200V foresees to load of the distributor the construction of a line of low voltage to 600÷1200V of suitable section and necessary length to the requested utilization, therefore a transformer MT/B- t T-i/BT of 100÷400 kVA to service also of other customers, a second transformer or autotransformer B1T1/BT of adequate power and the construction of the intake for the feeding in low voltage of the final customer. With the solution B 1 T 1 to the voltage 600÷1200 V the user doesn't have to build the local box with relative electric equipment and to worry about their maintenance. Says system according to the present invention offers the more wide guarantees of reliability and safety in the use, it easily results obtainable easily using elements, materials and equipment available and technically experimented already, therefore it is competitive from the economic point of view, besides in his conceptual simplicity it represents a notable solution in the field of the transport and the delivery of the electric energy. From how much previously described and illustrated can be seen that the invention reaches the preceded purposes. The found object of the present invention is susceptible of numerous variations all re- entering within the inventive concept.

Claims: Claims 1) System of transport and distribution e/o delivers of electric energy to industrial frequency characterized by the fact to transform the electric voltage from medium voltage (3000÷30000V) to a level of voltage understood between 600V and 1200V through three-phase transformers MT/ B 1 T1 of power 50, 100 or 160 kVA or about, to transport with normalized cable of low voltage, aerial or underground, or with other fit mean till to a near place to the utilization where the voltage suffers a second transformation to the level of voltage in use, generally 400/231 or 220/127 Volts and till 110 V through transformer or autotransformer B^/BT. 2) System of transport and distribution e/o delivers of electric energy to industrial frequency characterized by the fact to raise the electric voltage from the value in use, generally, 400 or 220V and till 1 10V to a level of voltage understood between 600V and 1200 V through transformers or autotransformers BT/ B1T1 to transport it with cable of low tension, aerial or underground, or with other fit mean till a near place to the utilization where the voltage suffers a second transformation to a level voltage in use, generally, 400/231 or 220/127V and till 1 10 Volts through transformers B1T1/BT of small power ( about 50 kVA). 3) System of transport and distribution e/o delivers of energy characterized by the fact to transform, through a three-phase transformer MT / (power nominal 160, 250 kVA, or around) that it has two delivery to the secondary one, the electric voltage from medium voltage (3000÷30000V) both to the value of voltage in use, generally, 400/231 or 220/127 Volts and till 110V for the users more neighbours to the place of transformation, both to a level of voltage understood between 600V and 1200V, to transport this last, for distant consumers, with cable of low voltage, aerial or underground, or with other fit mean till a near place to the utilization where the voltage generally suffers a second transformation to the level of voltage in use 400/231 or 220/127 Volts and till 110V. 4) System of transport and distribution e/o delivers of electric energy as to claims 1), 2) and 3) characterized by the fact that the voltage line 600÷1200V can be divided in two or more branches to supplied two or more transformers or autotransformers B 1 T 1 /BT of suitable powers

Inventors: IOVENE BRUNO, IOVENE, BRUNO
Applicants: IOVENE BRUNO, IOVENE, BRUNO
Application year: 2001
Main classification: H02J3
IPC codes: H02J3