Technical specifications of energy meter

Kilowatt-hour meters shall,in general,be constructed to IEC Publication521,Class1.0.All meters shall be of satisfactory design and good construction to ensure long life.The construction shall be such that the meter shall not be prone to produce appreciable noise in use.Design features which effectively lengthen the period during which the meter can be expected to operate without appreciable loss of accuracy under normal service conditions will be regarded as essential requirements.Meters shall be designed to operate on415/240 volt50Hz systems.The meter cover shall be either of non-metallic,full insulating,non-hygroscopic11on-ignitable thermosetting plastic material having low dirt absorption properties and distortion free under high temperature,eg,bakelite or all clear polycarbonate with W stabilized resign, eg Lexan.One dust-tight glass window in the case to permit a clear view of the rotor,registers and indicators.The glass shall be fitted so that it will be impossible to remove it without being damaged or breaking the meter seal.The glass window shall be secured with at least4retaining clips together with a suitable glue with good adhesive,sealing and resilient properties,eg,silicone glue or equivalent.It shall not deteriorate when exposed to sunlight.The meter cover shall be provided with a continuous gasket of suitable material to prevent entry of dust,etc.between the cover and the base.The gasket shall be fitted in a recessed groove in the cover to prevent dislodgement.polished black thermosetting plastic material,having low dili absorption propelties and distortion free under high temperature,eg,bakelite.The base and ternlinal compartment shall be moulded in one solid piece with no attachments where moisture could be trapped between the surface,or in two pieces but with suitable gasketing between the surfaces to exclude moisture,dust,etc.A separate cover shall close the terminals of the meter with provisions for sealing.The terminal cover shall be of the same material as the meter base.A diagram of connections showing the external connection shall be provided for meters with more than two terminals.The diagram shall be securely attached to the inside of the terminal cover.(a)It shall be possible to apply a sea1(s)to the case(s)in such a manner that access tothe working parts(other than those intended for use by the consumer)and to the electric and magnetic adjustments can he gained only by breaking the seal(s).The insulation of the meter circuits shall have adequate resistance and shall withstand voltage test as specified in lEe Publication No521or BS5685,1979or equivalent.The meter element unites)shall be substantially insulated and protected to withstand conditions of high humidity and full immersion in standard cleaning fluids such as perchloroethylene,trichloroethylene,trich10rotrifluroethane(Freon)during normal overhaul procedures.The meter shall further withstand 1.2/50microseconds standard full lighting impulse test of not less than10kVp standard.The direction of rotation of the rotor shall be from left to right when the rotor is viewed from the front of the meter.Removal and re-assembly of the rotor shall be a simple procedure not involving alteration to original positioning.High quality and stable magnetic bearing of the rotating dise system shall be a feature of the meter.The rotor to be supported by a symmetrical magnetic field set up by fixed and moving high coercivity permanent magnet with temperature compensation.Transverse forces shall be contained by fixed pin and guide bearings at each end of the rotor shaft.Bearing pins to be of polished stainless steel running in guides'precision moulded from low friction material.The magnets shall be of the high energy type.They shall be of a pole system with temperature compensation,and cast integrally into the meter frame. of manufactureb.Modelc.System of distributiond.The values of current and voltagee.Frequencyf.The number of revolutions per kWhg.Owner's number to be inscribed immediately below the rotor disc,and the numbersize shall be of minimum dimension of4mm x4mm visible from a distance of2 metres.Owner's number will be advised at the time of order.It shall be inked in black.h.Number of phases and wiresi.CT ratio to be used with the meter if it is a transformer rated meter.The acceptance sampling test is to be conducted in conjunction with the limits of error as specified in the IEC Publication No.521. If the sample failed the acceptance sampling test,the whole consignment shall be rejected. All meters shall have two screws in each current terminal for effectively clamping the extemalleads.The terminal material shall be brass of adequate cross-sectional to ensure maximum heat dissipation.The construction of the terminal shall be of the solid block design and nickel plated.The thickness between the inner surface of the terminal cable entry hole and the outer surface of the terminal block shall be not less than1.5mm.For self-contained meters,the left-hand terminal of each meter current-circuit,as seen from the front of the meter,shall be connected to the incoming mains.The main circuit of the supply side shall be connected directly to the voltage circuit of the meter.The voltage circuit shall be provided with discollilecting devices inside the meter or inside the terminal block and accessible only by opening the meter cover or terminal block cover.The cun'ent coil shall be made of copper with adequate cross-sectional area to enable the meter to carry the full overload current without excessive temperature rise and energy loss. The voltage coil shall be encapsulated in a resin-filled cup.The thickrless of the encapsulation shall be not less than2mm.A temperature compensating device shall be incorporated in the voltage coil assembly.The meter rotor shall start and continue to run with0.5per cent at basic CUlTent reference voltage,and unity power factor,All KWh meters shall be calibrated for use at30z at all points on the error curve between5 per cent of basic current and maximum current at Ullity power factor and between10per cent of basic current and maximUlll current at0.5per cent lagging power factor.All elements shall lie within the values 1.5per cent minus and1.5per cent plus when delivered. All calibration facilities shall be capable of fine/micrometric adjustment.The parts of the meter which are movable or adjustable for the purpose of calibration,shall be capable of further movement or adjustment as follows:a.Low load adjustment to provide for at least plus and minus4per cent change inspeed at5per cent basic current at reference voltage and at unity power factor.b.Inductive load adjustment to provide for at least plus and minus1per cent change inspeed at50per cent rated maximum current at reference voltage and0.5per cent power factor lagging.The energy register of the meter shall be of the cyclometer type of low friction design. Shafts shall be highly polished stainless steel.All wheels and pinions shall be lightweight aluminium pressing or brass and shall not be attacked by cleaning agents, e.g. perchloroethylene,trichloroethylene or trichlorofluro-ethane fluids.The registers shaH be arranged that it is self-locating upon removal and reinsertion.No free lubrication shall be used in the associated guide bearings.Certification period(period of time that the meter can be left in service without having to be called back for recalibration)shall be20years.When specified,KWh,KVAr or KVA maximum demand indicators shall be of a pointer dial pattern subtending a minimum angle of not less than270°.The zero position is to be in the left-hand quadrant of the scale.The MDI shall comply with the requirements ofIEC Publication211Class 1.0.。