This European Standard applies to newly manufactured watt-hour meters, measuring active electrical energy, intended for residential, commercial and light industrial use, for use on 50 Hz electrical networks. It specifies general requirements and type tests methods. It applies to electromechanical or static watt-hour meters for indoor and outdoor application, consisting of a measuring element and register s enclosed in a meter case. It also applies to operation indicator s and test output s. If the meter has a measuring element s for more than one type of energy multi-energy meters , or when other functional elements, like maximum demand indicators, electronic tariff registers, time switches, ripple control receivers, data communication interfaces, etc. The test levels are regarded as minimum values to guarantee the proper functioning of the meter under normal working conditions.
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EN BBDC-Aftersales draft A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and shall not be referred to as a European Standard.
Dr Project: ? It is submitted to the Unique Acceptance Procedure. See Annex ZZ. It specifies general requirements and type tests methods. This standard distinguishes between: — — — — — electromechanical and static meters; meters of class indexes A, B and C; direct connected and transformer operated meters; protective class I and protective class II meters; meters intended to be used indoors and outdoors.
It does not apply to: — — — watt-hour meters where the voltage across the connection terminals exceeds V line-to-line voltage for meters for polyphase systems ; portable meters; reference meters. For rack-mounted meters, the mechanical properties are not covered in this standard. The test levels are regarded as minimum values to guarantee the proper functioning of the meter under normal working conditions. For special applications, other test levels might be necessary and should be agreed on between the user and the manufacturer.
For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document including any amendments applies. It also applies to operation indicator s and test output s. Expressions of the performance of electrical and electronic measuring equipment have been taken from EN Where there is a difference between the definitions in this glossary and those contained in product standards produced by TC 13, then the latter shall take precedence in applications of the relevant standard.
The SI unit for active power is the watt. The type may have several values of reference current and reference voltage. Meters are designated by the manufacturer by one or more groups of letters or numbers, or a combination of letters and numbers. Each type has one designation only. Dr aft for vo 3.
NOTE 2 Where the number of ampere-turns would lead to a number of turns other than a whole number, the product of the number of turns of the windings by the value of the reference current may differ from that of the sample meter s representative of the type.
It is advisable to choose the next number immediately above or below in order to have whole numbers of turns. NOTE 3 The ratio of the highest to the lowest reference speed of the rotors of each of the meters of the same type shall not exceed 1,5. NOTE The type is represented by the sample meter s intended for the type tests, whose characteristics reference current and reference voltage are chosen from the values given in the tables proposed by the manufacturer.
It is usually designed and operated to obtain the highest accuracy and stability in a controlled laboratory environment [IEC , 3. A single electronic display may be used with multiple electronic memories to form multiple electronic registers. Dr [IEV modified] 3. It may be a single-position socket for one meter or a multiple-position socket for two or more meters [IEV modified] aft 3.
At and above Imin, up to Itr relaxed accuracy requirements apply 3. Repeatability conditions include: the same measurement procedure; the same observer; the same measuring instrument, used under the same conditions; the same location; repetition over a short period. For this range, relaxed accuracy requirements may be specified [IEC , 3. An influence quantity is a disturbance if for that influence quantity the rated operating conditions are not specified 3.
NOTE 2 A voltage dip is a two-dimensional electromagnetic disturbance, the level of which is determined by both voltage and time duration. It generally comprises electromagnets with their control devices [IEC , 3. It comprises one or more magnets and their adjusting devices [IEC , 3.
The standard values of the rated secondary current of the current transformers are 1 A, 2 A and 5 A, but the preferred value is 5 A. The specified measuring range of the meter may cover the specified measuring ranges of current transformers with different rated currents.
Mechanical requirements and tests General mechanical requirements The manufacturer shall specify the mechanical environment the meter is intended for. NOTE Meters are generally used in locations where levels of vibration and shock are of low significance.
All parts, which are subject to corrosion under normal working conditions shall be protected effectively. Any protective coating shall not be liable to damage by ordinary handling nor damage due to exposure to air, under normal working conditions. Outdoor meters shall withstand solar radiation. NOTE For meters for special use in corrosive atmospheres, additional requirements shall be fixed in the purchase contract e.
The components shall be reliably fastened and secured against loosening. The construction of meters shall be such as to minimize the risks of short-circuiting of the insulation between live parts and accessible conductive parts due to accidental loosening or unscrewing of the wiring, screws, etc.
The cover shall not be removable without the use of a tool. The case shall be so constructed and arranged that any non-permanent deformation cannot prevent the satisfactory operation of the meter. The mechanical strength of the meter shall be tested with the following tests.
The result of the test is satisfactory if the meter case and terminal cover do not sustain damage, which could affect the function of the meter and it is not possible to touch live parts. Slight damage, which does not impair the protection against indirect contact or the penetration of solid objects, dust and water is acceptable.
After the test, the meter shall show no damage, nor change of the information and shall operate correctly in accordance with the requirements of the relevant standard. In order to satisfy such requirements when choosing insulating materials for the terminal block s , adequate testing of materials shall be taken into account.
Dr The terminal block shall be so constructed that the meter during any deformation caused by rated operating conditions shall comply with the insulation requirements and the clearance and creepage distances within this standard.
The holes in the insulating material, which form an extension of the terminal holes, shall be of sufficient size to accommodate also the insulation of the conductors. The manner of fixing the conductors to the terminals shall ensure adequate and durable contact such that there is no risk of loosening or undue heating.
Screw connections transmitting contact force and screw fixings, which may be loosened and tightened several times during the life of the meter shall screw into a metal nut. These windows shall be of transparent material, which cannot be removed undamaged without breaking the seal s.
Electrical connections shall be so designed that contact pressure is not transmitted through insulating material. For current circuits, the voltage is considered to be the same as for the related voltage circuit. Terminals with different potentials, which are grouped close together, shall be protected against accidental short-circuiting.
Protection may be obtained by insulating barriers. Terminals of one current circuit are considered to be at the same potential.
The terminals, the conductor fixing screws or the external or internal conductors shall not be liable to come into contact with metal terminal covers. The protective earth terminal, if any: a b c d shall be electrically bonded to the accessible metal parts; should, if possible, form part of the meter base; should preferably be located adjacent to its terminal block; e shall be clearly identified by the graphical symbol IEC Protective earth ground After installation, it shall not be possible to loosen the protective earth terminal without the use of a tool.
The terminal cover shall enclose the actual terminals, the conductor fixing screws and, unless otherwise specified, a suitable length of the external conductors and their insulation.
When the meter is panel-mounted, no access to the terminals shall be possible without breaking the seal s of the terminal cover s. The clearance between the terminal cover, if made of metal, and the upper surface of the screws when screwed down to the maximum applicable conductor fitted shall be not less than the relevant values indicated in Table 4 and Table 5.
If such small parts are accessible by the standard test finger as specified in EN from outside the case, then they shall be additionally isolated from live parts by supplementary insulation against failure of basic insulation or loosening of live parts.
The insulating properties of lacquer, enamel, ordinary paper, cotton, oxide film on metal parts, adhesive film and sealing compound, or similar unsure materials, shall not be regarded as sufficient for supplementary insulation. For the terminal block and terminal cover of such a meter, reinforced insulation is sufficient. Resistance to heat and fire The terminal block, the terminal cover and the meter case shall ensure reasonable safety against spread of fire.
They should not be ignited by thermal overload of live parts in contact with them. To comply therewith they shall fulfil the following test. The tests shall be carried out according to EN , under the following conditions: a — — — — Protection against penetration of dust: meter in non-operating condition and mounted on an artificial wall; for indoor meters only, the same atmospheric pressure is maintained inside the meter as outside neither under- nor over-pressure ; first characteristic digit: 5 IP5X.
Any ingress of dust shall be only in a quantity not impairing the operation of the meter. An insulation test according to 7. It can be either electromechanical or electronic comprising both memory ies and display. It shall be easily readable under normal conditions of use. In the case of an electronic register the corresponding non-volatile memory shall have a minimum retention time of four months.
Longer retention time of the non-volatile memory should be the subject of purchase contract. In the case of multiple values presented by a single display it shall be possible to display the content of all relevant memories. When displaying the contents of the memory ies , the clear and unambiguous identification of each value shall be possible and, for automatic sequencing displays, each display of register for billing purposes shall be retained for a minimum of 5 s.
The active tariff rate shall be indicated. If the terminal block is integral with the meter base, it is sufficient to carry out the test only on the terminal block. The principal unit for the measured values shall be the kilowatt-hour kWh , or the megawatt-hour MWh. The principal unit shall be shown adjacent to the measured value. For electromechanical registers, register markings shall be indelible and easily readable.
When continuously rotating, the drum showing the lowest values shall be graduated and numbered in ten divisions, each division being subdivided into ten parts, or any other arrangement ensuring the same reading accuracy.
The drums, which indicate a decimal fraction of the unit shall be marked differently when they are visible. Every numerical element of an electronic display shall be able to show all the numbers from "zero" to "nine". For testing purposes, it shall be possible to increase the resolution to 0,01 times the principal unit.
The register shall be able to record and display, starting from zero, for a minimum of 4 h, the energy corresponding to maximum current at reference voltage and unity power factor. NOTE 2 Values higher than 4 h should be subject of purchase contract. The display of the total quantity of electrical energy supplied or the displays from which the total quantity supplied can be derived, whole or partial reference to which is the basis for payment, shall not be able to be reset during use.
BS EN 50470-1:2006+A1:2018