Precautions for purchasing single-phase electronic

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Precautions for purchasing single-phase electronic watt hour meter

1. Check the basic technical conditions that the manufacturer must have

5. Clamping the end of sample 1 on the upper jaw of the watt hour meter is a national compulsory inspection measuring instrument. According to the provisions of the measurement Law, the selected watt hour meter must have a manufacturing measuring instrument license (CMC certificate) issued by the Technical Supervision Bureau at or above the provincial level. This is a necessary condition and legal procedure for the manufacturer of electric energy meter. It can prove that the factory has basic facilities, personnel and testing instruments and equipment, and is a product that can be produced and sold. However, in the current fierce market competition, power supply enterprises have more choices. Therefore, they can also compare other documents that prove product quality. For example, the appraisal report and life test report of the authoritative department, listed in the "national recommended catalogue of equipment products and manufacturers required for urban and rural power construction and transformation" of the State Economic and Trade Commission, ISO9000 quality certification, etc. These are not easy to oxidize and deteriorate during use and storage. They are important documents to prove product quality

due to the fierce price competition among manufacturers, it is not enough to rely on these documents only according to experience, which can only prove that there is a basis for selection. The next step is to test the electric energy meter produced by the manufacturer according to the performance characteristics of the electronic electric energy meter, the national inspection regulations, and the actual conditions of local electricity and climate

2. Carry out pollution-free, low noise and high efficiency inspection on the physical energy meter

carry out inspection on the physical energy meter sent by the manufacturer mainly from the following aspects. Namely: mechanical requirements, adaptable climatic conditions, electrical requirements, electromagnetic compatibility and accuracy requirements. These five aspects are clearly stipulated in the national standard level 1 and level 2 static AC active energy meters (gb/t). Some of the test and inspection items in the regulations are generally conditional inspection by prefecture level and county-level power supply enterprises, but a considerable number of items are not yet conditional inspection. The following is a brief description of the points needing attention and solutions

(1) mechanical requirements:

most of the mechanical requirements can be inspected through visual inspection and simple test methods. For example: four prevention (electric shock prevention; over temperature prevention; flame spread prevention; solid foreign matters, dust and water prevention); The lead seal is convenient and reliable (the internal components of the instrument can be touched only after the lead seal is damaged); The wiring terminal shall have sufficient insulation performance and mechanical strength; The structure and assembly of the case shall ensure that the normal operation of the instrument will not be hindered in case of non permanent deformation According to materials, it can be divided into metal and non-metal material testing machines; Work; Nameplate, wiring diagram and terminal mark meet the requirements, etc. These requirements are the most basic requirements to ensure the safe operation of electric energy meters, which can be observed and identified by experience. Selection must not be ignored. Special terminal boards shall be made of flame retardant materials, such as injection phenolic resin; When the shell is made of ABS engineering plastics, check whether it is flame retardant; The shell shall not have obvious deformation to affect the sealing performance and the internal components shall have obvious relative displacement

(2) accuracy requirements:

accuracy requirements include the inspection of current and power factor change, voltage change, frequency change, start-up test, potential test, word walking test and other items, which can be inspected by municipal and county-level power supply enterprises. Generally, the linearity of electronic watt hour meters is good within the load range specified in the regulations, but the actual and accurate load range of meters from different manufacturers is very different. Because the actual load current on site changes frequently, the wider the load range that can be accurately measured, the better the load performance of the meter. In some rural areas, the electric voltage fluctuates greatly. Pay attention to the error of electric energy meter under the condition of voltage fluctuation limit. Especially for the light load error at low voltage and whether the words of the watt hour meter are powerful, check whether the DC power supply voltage in the meter can not fall below the working voltage of the meter and the chip, and the ripple of the DC power supply can not increase significantly

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