The flameproof surface of ATEX explosion proof induction motor is almost the main reason for the failure of explosion proof motor

n August 2025, the results of China's national and local electric motor quality spot checks for 2025 were released, They primarily focused on ATEX explosion proof motor failures, primarily due to substandard flameproof surfaces, This surface has become a common culprit for failures in explosion proof induction motors.

As one of China's most professional manufacturers of ATEX explosion proof induction motors, the principle of flameproofing is to enclose the live components of a three phase explosion proof motor within a specially designed enclosure (an explosion-proof motor housing). This enclosure isolates sparks and arcs generated by the electrical components within the enclosure from the explosive mixture outside. It can withstand the explosive pressure generated by the explosive mixture entering the enclosure and being ignited by sparks and arcs from the electrical equipment within the enclosure without damaging the outer casing. Furthermore, it prevents the explosion products within the enclosure from propagating to the explosive mixture outside the enclosure, preventing combustion or explosion of the explosive mixture outside the enclosure. Therefore, the components of explosion-proof motors differ from those of ordinary motors. The precise definition of the flameproof surface in an ATEX explosion-proof motor is the flameproof joint. This refers to the area where corresponding surfaces of different components of the flameproof enclosure fit together (or where the enclosure is connected), and where flames or combustion products could potentially be transmitted from the inside of the enclosure to the outside. Examples of flameproof joints include the motor frame, end caps, inner bearing covers, and terminal boxes.

From a production and processing perspective, as long as the parts are manufactured according to the drawings and necessary tests are conducted, there's no significant difficulty. So why are these issues so frequently discovered during spot checks of three phase explosion proof motors? Shandong Langrui Electric Motor, a manufacturer, speculates that the following reasons may be the cause:

1, Manufacturers lack awareness of explosion-proof motor safety, leading to haphazard processing of the flameproof surface. This problem is particularly acute in companies that outsource production and have poorly controlled inspection processes. Smaller motor manufacturers, in particular, often copycat.

2, Inadequate quality control is employed in component production and processing, leading to a failure to effectively identify parts with quality risks. For example, some manufacturers include hydrostatic testing of parts but fail to strictly adhere to the requirements.

3, Due to a lack of understanding of explosion-proof motors, they may mix parts with general motors. Some manufacturers even harbor a sense of luck, believing that quality issues won't happen to them.