Analysis of quality problems in explosion-proof electric heater industry

- Aug 07, 2020-

The analysis of the quality problems of the explosion-proof electric heater industry has analyzed the rapid development of the domestic explosion-proof electrical product industry. Both the product variety and the technical level have made great progress, and the explosion-proof electrical industry system that meets the needs of China's economic construction and development has been established. It has made great contributions to the rapid development of China's coal, petroleum, chemical and other industries. The overall level of domestic explosion-proof electric heater products has greatly shortened the gap with the international advanced level, and some products have approached or caught up with the international advanced level. The overall status of my country's explosion-proof electrical industry and product quality is good. However, for a period of time, due to the failure of the industry and corporate management to keep up, the development of the industry has been blindly confused, and there have been many problems in product quality, some of which are more serious. Some private enterprises and township and village enterprises have forgotten their profits, blindly pursue profits, ignore the safety of their lives and state property, cut corners and make shoddy work. In some regions, counterfeit, shoddy and unlicensed (no production license, no explosion-proof certificate) products flood the market. The above situation not only seriously damages the interests of companies that value product quality and disrupts the normal market order, but also brings great hidden dangers to users and social safety. Not long ago, the National Quality Supervision and Inspection Center for Explosion-proof Electrical Products organized a comprehensive survey of the quality of the industry. The following surveys of explosion-proof motors, fuel dispensers, explosion-proof electrical appliances, lamps and other products in their production links, circulation areas and use departments The existing quality problems are introduced.

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1. Quality problems and analysis in the industry

 

(1) Quality problems found in production

1. The overall quality of explosion-proof motor products is good, but there are some quality problems.

(1) Users report that there are many "shaft holding" quality accidents in individual high-voltage (6kV) medium-sized flameproof motor bearing transmission structure and bearing flameproof structure.

(2) The reliability of the winding quality of explosion-proof motor is not high. Users report that there are many occurrences of winding short-circuit, open-circuit accidents and burnout caused by short-circuit, among which explosion-proof motors for mining are more prominent.

(3) The noise and vibration quality of explosion-proof motors are poor, especially for medium-sized explosion-proof motors, and users have more opinions.

(4) There are quality problems in the manufacturing and assembly of explosion-proof motors. The roughness of the explosion-proof surface of some products is not up to the standard; the ovality of the explosion-proof surface is often out of tolerance; the machine base processing technology is difficult to ensure the concentricity of the explosion-proof surface; The explosion-proof surface is not well protected during the transfer process; the thickness of the explosion-proof surface is inconsistent; the arc-resistant paint is not coated in the junction box, and the iron core burrs are out of tolerance; the stator windings are not cleaned before assembly, sometimes there are iron filings and other debris; windings The cleaning is not clean after dipping, and there are many paint bumps; phenomena such as barbaric assembly often occur.

(5) The appearance of the motor is of poor quality, some of the surface is not cleaned well, and some of the heat sink is badly damaged.

 

2. The product quality of explosion-proof refueling machine varies from good to bad.


The quality problems of explosion-proof tanker products we found in our investigation mainly include the following aspects:

(1) The selection of explosion-proof electrical appliances does not meet the requirements of explosion-proof standards. Explosion-proof electrical products should be used correctly, but a few of them use increased safety products. The explosion-proof electrical products selected by some manufacturers are of poor quality, and some are even counterfeit or unlicensed (no explosion-proof certificate, production license) products.

(2) Internal wiring between components

Many of the selection and connection do not meet the requirements of explosion-proof standards.

(3) The creepage distance and electrical clearance of the circuit in the electrical system junction box cannot meet the requirements of explosion-proof standards.

(4) The isolation structure of adjacent areas in the tanker cannot guarantee explosion-proof safety requirements.

(5) The performance of the selected rubber and other sealing materials is unqualified, and the amount of oil and gas leakage is large.

(6) The structural materials of the fuel dispenser do not meet the requirements of explosion-proof standards, such as the surface resistance requirements of plastic shells, and the requirements of certain metal content specified by light alloy materials to prevent mechanical friction and sparks, etc., have exceeded the standards. 

(7) After the national competent authority issued regulations on adding tax control functions to fuel dispensers, the tax control devices installed in many production plants or gas stations did not meet the requirements of explosion-proof standards.

(8) Other non-explosion-proof performance quality problems. For example, the quality of the metering system is unstable and the metering accuracy does not meet the standard; when the flow rate is small, the metering accuracy is low, and it is difficult to prevent abnormal modification of the metering accuracy.