GENERAL LEAFLET MEDIUM VOLTAGE ENERGY TRANSMISSION SYSTEM THOUGHTS ON THE DISTRIBUTION OF ELECTRICAL ENERGY TIT

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 APPLICATION EXAMPLE :…………………………………………………..………… APPENDIX : Number of lamps per TIT / LV...

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...

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 lim- ited 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...

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...

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...

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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...

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...