What is an explosion-proof motor? Why can it be explosion-proof?-Xinda Motor- electric motors and EV accessories supplier|INDEX--

What is an explosion-proof motor? Why can it be explosion-proof?

Date：2023-07-08　　　Author：Shandong Xinda Motor Co., Ltd.

Explosion-proof motor is a kind of motor that can be used in flammable and explosive places, and does not generate electric sparks during operation. Explosion-proof motors are mainly used in coal mines, oil and gas, petrochemical and chemical industries. In addition, it is also widely used in textile, metallurgy, city gas, transportation, grain and oil processing, papermaking, medicine and other departments. As the main power equipment, explosion-proof motors are usually used to drive pumps, fans, compressors and other transmission machinery.

In our country, explosion-proof motors are managed according to production licenses, that is, production units must produce and sell under the condition of obtaining a production license; compared with ordinary motors, explosion-proof motors have relatively strict requirements for components, production management, and test items. Harsh, explosion-proof motors can be used in harsh environments with flammable and explosive gases in environmental conditions, while ordinary motors do not have this qualification.

Why can explosion-proof motor be explosion-proof?

The reason why the explosion-proof motor is explosion-proof is not that it can prevent the occurrence of other explosive events, but that for the motor body, through necessary measures, it can prevent the occurrence of explosive events due to problems with the motor body. For example, when the electrical fault occurs in the motor winding, the spark effect derived from it will be controlled in the inner cavity of the motor, and will not cause other explosive problems outside the motor body.

From the analysis of the design principles of explosion-proof motors, the basic idea is to consume the energy of factors that may cause explosions through sufficient protection levels, and sufficiently long fitting lengths and small enough fitting gaps between parts; Among them, the casing or parts that are in direct contact with the external environment will not cause explosive sparks and other consequences due to their operation, so the materials of parts of explosion-proof motors will also have special regulations.

From the analysis of the application requirements of explosion-proof motors, it can be considered that explosion-proof motors must have sufficient self-discipline and quality, and must ensure that no conditions that cause explosions occur during the operation of the motor. This is also the characteristic of explosion-proof motors that is different from ordinary motors.

Explosion-proof motor classification:

1. According to the motor principle, it can be divided into explosion-proof asynchronous motor, explosion-proof synchronous motor, explosion-proof DC motor, etc.

2. According to the place of use, it can be divided into coal mine explosion-proof motors and factory explosion-proof motors.

3. According to the principle of explosion-proof, it can be divided into flameproof motors, increased safety motors, positive pressure motors, non-spark motors and dust explosion-proof motors.

4. According to the supporting main engine, it can be divided into explosion-proof motors for coal mine conveyors, explosion-proof motors for coal mine winches, explosion-proof motors for rock installation machines, explosion-proof motors for local coal mine fans, explosion-proof motors for valves, explosion-proof motors for loud fans, explosion-proof motors for ships, explosion-proof motors for lifting metallurgy, Increased safety brushless excitation synchronous motor hydrogenation device, etc. In addition, it can also be classified according to technical indicators such as rated voltage and efficiency, such as high-voltage explosion-proof motors, high-efficiency explosion-proof motors, high-slip explosion-proof motors, and high starting torque explosion-proof motors.

How different types of explosion-proof motors work:

1. Explosion-proof motor: The live parts of the motor are placed in a special casing. The casing has the function of isolating the sparks and arcs generated by the electrical components from the explosive mixture in the casing, and can withstand the explosion caused by the spark and arc detonation of the electrical equipment in the casing. pressure, the shell is not damaged. At the same time, this type of explosion-proof motor can prevent the explosive products inside the shell from spreading to the explosive mixture outside the shell, without causing the explosive mixture outside the shell to burn and explode. This special enclosure is called an explosion-proof motor.

2. Increased safety explosion-proof motor: Under normal operating conditions, some mechanical, electrical, and thermal protection measures are taken on the motor structure that does not generate arcs, sparks, or dangerous high temperatures to further avoid the danger of arcs, sparks, or high temperatures, and ensure its explosion-proof safety.

3. Positive pressure explosion-proof motor: Introduce the protective gas into the motor casing, keep the internal protective gas pressure higher than the surrounding explosive environment, and prevent the external explosive mixture from entering the casing.

4. Non-sparking explosion-proof motors: design and manufacturing measures are taken to ensure that the equipment does not generate arcs, sparks or dangerous temperatures during normal operation, and generally does not cause electrical or mechanical failures, achieving explosion-proof effects. Compared with the increased safety type explosion-proof motor, except for the insulation dielectric strength test voltage, winding temperature rise, and TE starting current, there are no special regulations like the increased safety motor, and other aspects are the same as the design requirements of the increased safety motor.

5. Dust explosion-proof motor: designed and manufactured under specified conditions to prevent combustible dust from entering or entering, without hindering the safe operation of the equipment, and the dust accumulated inside is not easy to cause ignition hazard, ensuring that the surrounding explosive mixture will not explode when used.

In short, no matter what type of explosion-proof motor, its casing has a high degree of sealing to reduce or prevent dust from entering the casing. Even if it enters, it will not cause an ignition hazard. The surface temperature of the casing does not exceed the specified temperature. The working principle of the explosion-proof motor is to play an explosion-proof role as a running motor in a place where there is a risk of explosion.

Common fault types of explosion-proof motors

Explosion-proof motors will inevitably have some failures during daily use. The common types of failures are as follows:

1. Damage to the explosion-proof surface

The explosion-proof surface is also called the explosion-proof surface, and damage to this part will seriously affect the explosion-proof effect of the explosion-proof motor. Generally speaking, there are many reasons for damage to the explosion-proof surface, which may occur during the production process, assembly process and use process. It may also be due to failure to operate in accordance with relevant technical regulations during routine maintenance and maintenance, resulting in damage to the explosion-proof surface. In addition, condensation inside the motor is prone to occur in a humid environment. If it is not properly resolved at this time, it will also lead to corrosion of the explosion-proof surface.

2. Open phase operation

When a phase loss occurs, the motor can still rotate, but it is easy for the current to exceed the normal value. If the problem cannot be found and solved in time, it will cause the motor to overheat, the control circuit equipment to fail, and the cable to burn out due to lack of phase.

3. Unbalanced three-phase current

Current imbalance may occur during the use of explosion-proof motors, which will lead to a decrease in the operating stability of the equipment. Generally speaking, this problem is mainly related to the voltage stability of the three-phase power supply and the number of three-phase turns. The unbalanced three-phase load will increase the energy consumption of the equipment, affect the insulation performance of the motor, and also have the risk of burning the winding.

4. The no-load current is too large

During the operation of the explosion-proof motor, the current design needs to be carried out according to the actual operating conditions. Usually, the no-load current of the equipment is related to the number of pole pairs of the motor, the magnetic material and the power of the motor. In the actual use process, it often occurs that the current exceeds 50%. At this time, the no-load current is relatively high, and there is a certain high risk of use. There will also be a problem that the rated current is lower than 20%. At this time, the no-load current is low, which will easily affect the operation effect of the equipment and is not conducive to the requirements of operation stability.

Common faults and maintenance optimization strategies of explosion-proof motors

1. Strengthen daily maintenance and management

The daily maintenance and management of explosion-proof motors is a necessary condition to ensure the scientific operation of equipment. In the daily maintenance process, the most critical link is to provide a good working environment and reduce the risk of various problems on the flameproof surface of the motor as much as possible, so as to ensure the contact effect of the contact surface.

2. Establish a perfect maintenance system

Establishing a sound maintenance system also plays a certain role in the scientific operation of explosion-proof motors. Construct the management files of explosion-proof motors within the enterprise, record the maintenance and repair history of explosion-proof motors, evaluate the operating status, formulate a comprehensive maintenance management plan, strengthen the motor pre-inspection management mode, eliminate faults in the bud, and ensure Operational reliability of explosion-proof motors.

Explosion-proof motors play an irreplaceable role in modern chemical production, and their operational stability is not only related to production safety, but also closely related to the production efficiency of enterprises. In addition to strengthening the daily maintenance and management of explosion-proof motors, the user unit needs to further establish and improve the maintenance system and improve the technical execution capabilities of personnel, so as to better meet the operation stability requirements of explosion-proof motors and create a good environment for the sustainable and healthy development of the industry. condition.

What is an explosion-proof motor? Why can it be explosion-proof?

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