Electrical Installation Guide 2009 - the global specialist in energy ...

B - Connection to the MV publicdistribution network2 Procedure for the establishmentof a new substationThe utility must give specific information to theprospective consumer.2.2 Project studiesFrom the information provided by the consumer, the power-supplier must indicate:The type of power supply proposed, and define:b The kind of power-supply system: overheadline or underground-cable networkb Service connection details: single-line service, ring-main installation, or parallelfeeders, etc.b Power (kVA) limit and fault current levelThe nominal voltage and rated voltage (Highest voltage for equipment)Existing or future, depending on the development of the system.Metering details which define:b The cost of connection to the power networkb Tariff details (consumption and standing charges)B15The utility must give official approval of theequipment to be installed in the substation,and of proposed methods of installation.2.3 ImplementationBefore any installation work is started, the official agreement of the power-suppliermust be obtained. The request for approval must include the following information,largely based on the preliminary exchanges noted above:b Location of the proposed substationb Single-line diagram of power circuits and connections, together with earthingcircuitproposalsb Full details of electrical equipment to be installed, including performancecharacteristicsb Layout of equipment and provision for metering componentsb Arrangements for power-factor improvement if requiredb Arrangements provided for emergency standby power plant (MV or LV) if eventuallyrequiredAfter testing and checking of the installation byan independent test authority, a certificate isgranted which permits the substation to be putinto service.2.4 CommissioningWhen required by the authority, commissioning tests must be successfully completedbefore authority is given to energize the installation from the power supply system.Even if no test is required by the authority it is better to do the following verification tests:b Measurement of earth-electrode resistancesb Continuity of all equipotential earth-and safety bonding conductorsb Inspection and functional testing of all MV componentsb Insulation checks of MV equipmentb Dielectric strength test of transformer oil (and switchgear oil if appropriate), ifapplicableb Inspection and testing of the LV installation in the substationb Checks on all interlocks (mechanical key and electrical) and on all automaticsequencesb Checks on correct protective-relay operation and settingsIt is also imperative to check that all equipment is provided, such that any properlyexecuted operation can be carried out in complete safety. On receipt of the certificateof conformity (if required):b Personnel of the power-supply authority will energize the MV equipment and checkfor correct operation of the meteringb The installation contractor is responsible for testing and connection of theLV installationWhen finally the substation is operational:b The substation and all equipment belongs to the consumerb The power-supply authority has operational control over all MV switchgear in thesubstation, e.g. the two incoming load-break switches and the transformer MV switch(or CB) in the case of a RingMainUnit, together with all associated MV earthing switchesb The power-supply personnel has unrestricted access to the MV equipmentb The consumer has independent control of the MV switch (or CB) of the transformer(s)only, the consumer is responsible for the maintenance of all substation equipment,and must request the power-supply authority to isolate and earth the switchgear toallow maintenance work to proceed. The power supplier must issue a signed permitto-workto the consumers maintenance personnel, together with keys of locked-offisolators, etc. at which the isolation has been carried out.© Schneider Electric - all rights reservedSchneider Electric - Electrical installation guide 2009