The basic operating states of motors are horizontal and vertical. The operating conditions of motors are also specified in the product's user manual. However, special environmental conditions may have different performance requirements for motors, which must be met during the design and manufacturing process.
The basic operating states of motors are horizontal and vertical. The operating conditions of motors are also specified in the product's user manual. However, special environmental conditions may have different performance requirements for motors, which must be met during the design and manufacturing process.
1 Explosion-proof motor
Explosion-proof motors are used in locations containing flammable and explosive materials and can be broadly classified into two categories: those for factories and those for coal mines. Based on their operating conditions and explosion-proof measures, they are further divided into six categories, including flameproof and explosion-proof safety types. The explosion-proof principle of flameproof motors is as follows: First, when an internal explosion occurs, the gap wall must be long enough to absorb heat and impede the flame as it travels through a designated gap, significantly reducing the transmitted energy and temperature, thus preventing an explosion of the explosive mixture outside the motor. Second, certain components of the motor must possess sufficient strength.
2 Motors for High-Altitude Environments
Plateaus refer to areas with an altitude of 1000m to 4000m. The characteristics of a plateau environment include low air pressure, low temperature with large daily temperature variations, low absolute humidity, and strong solar radiation. The low air density at low pressure can increase the temperature rise of air-cooled products; furthermore, due to the decreased dielectric strength of air, anti-corona measures must be strengthened when designing the insulation structure of high-voltage motors.
Large daily temperature fluctuations can easily cause deformation or cracking of mechanical components in motors. High solar radiation intensity can increase the temperature of outdoor motors, and the presence of oxygen and moisture can accelerate the aging of organic insulation materials and coatings, shortening their lifespan. The impact is even more severe when plastic products are used as external components of the motor. Therefore, the use of plastic parts should be approached with caution.
3. Environmental protection requirements for motor structural design
The environmental pollution caused by motors during operation mainly comes from three aspects: vibration and noise, electromagnetic interference, and the heated cooling medium discharged from the motor. Generally speaking, the former is the most significant. Electromagnetic interference originates from the commutation sparks of DC motors and AC commutator motors, and is usually addressed by connecting filter capacitors in parallel at the output terminals.
If such interference can severely affect the normal operation of other surrounding equipment, such as motors used in measuring devices or audio equipment, electromagnetic shielding can be used to completely enclose the motor if necessary. The hot air exhausted from the motor raises the ambient temperature and generates dust. Therefore, for medium and large motors with large cooling airflow, a closed-loop cooling system must be used in the structural design.
4 Marine Electric Motors
The operating environment can range from a maximum annual temperature of 45℃ to a minimum of -25℃. Motors installed on or near the deck must also be considered for the effects of solar radiation, rain, wind, salt spray, and mold. Motors in the engine room must also be considered for the effects of oil mist. Secondly, ships frequently encounter strong winds and waves, causing them to roll and heel . Therefore, general marine motors should be able to operate normally under conditions of 15° heel, 10° trim, and 23.5° roll, while motors for emergency equipment should be able to operate normally under conditions of 22.5 ° heel and 10° trim. Considering the need for easy disassembly and inspection of the stator or rotor during in-ship repairs, motor housings are often designed as two-part modular structures or box-type structures.
Furthermore, to make full use of the ship's cabin space, the motor is not necessarily cylindrical in shape, but is often designed as octagonal or other shapes (similar situations exist for electric locomotive motors). Therefore, marine motors have certain characteristics in terms of their structural type, material selection, insulation treatment, and surface protection.
5. The impact of transportation conditions on motor structure
For small and medium-sized motors and some medium and large-sized motors that are assembled and shipped as complete units, since their volume and weight do not exceed the limits for rail and road transport, and the vibration acceleration caused by trains, trucks, or airplanes during transport is less than 3g, as long as the packaging meets the requirements, it can be said that the transport conditions for these motors have no special requirements for their structure. However, for large generators, especially hydroelectric generators, whose weight can reach thousands of tons or more, and whose stator and rotor diameters can reach 10-20 meters or more, it is generally impossible to transport them as complete units by truck or train. Therefore, they can only be transported as large components, taking into account the transport limits for large components. Long-distance land transport mainly relies on rail, with road transport only used when the installation site is not near a railway. Ship transport is generally combined with rail transport; therefore, the following discussion only addresses the limits for rail transport.
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