The special environmental conditions of motors can be classified into two major categories based on the nature of the environmental factors: natural climate environments and industrial environments. Natural climate environments mainly include tropical, marine, cold, underground and plateau environments; industrial environments mainly include corrosive environments, explosive environments, high and low temperatures, high and low pressures, solid particles and dust, high-energy radiation and special mechanical loads, etc. The influence of special environments on motor insulation.
Temperature influence
Due to the high ambient temperature affecting the motor’s heat dissipation, its output power decreases. The strong effect of high temperature and ultraviolet rays accelerates the aging of insulating materials. In dry and hot areas, the relative humidity sometimes drops to 3%. High temperature and dryness cause insulating materials to become dry, wrinkled, deformed and cracked. High temperature is prone to cause the loss of potting compound. Low temperature makes rubber and plastic harden, become brittle and crack, and causes lubricating oil and coolant to freeze.
High humidity and moisture influence
High relative humidity can cause water films to form on the surface. When the humidity exceeds 95%, water droplets often condense inside the motor, which makes metal parts prone to rusting, lubricating grease prone to moisture absorption and deterioration, and some insulating materials prone to swelling due to moisture absorption or becoming soft and sticky. Mechanical and electrical performance deteriorates, and there is a high risk of insulation breakdown and surface flashover.
Mold influence
In a high-temperature and high-humidity environment, mold is most likely to grow. The secretions of mold can corrode metals and insulating materials, causing the insulation to age rapidly and leading to short-circuit accidents.
Dust and sand particles
Dust (including industrial dust) refers to particles with diameters ranging from 1 to 150 micrometers; sand dust refers to quartz particles with diameters ranging from 10 to 1000 micrometers. When dust and sand deposits accumulate on the insulation surface, they will cause a decrease in electrical insulation performance due to moisture absorption, and conductive dust is more likely to cause insulation leakage or short circuit accidents.Both acidic and alkaline corrosive dusts are prone to deliquescence, thereby causing corrosion of metal components and insulating parts. When dust and sand enter the motor, it can cause mechanical failures and component wear. If the amount is large, it will clog the air duct and affect ventilation and heat dissipation. Therefore, for motors used in industrial dusty areas and outdoor sand-dust regions, measures to prevent sand and dust must be taken.
Salt spray influence
When the turbulent waves in the ocean strike the rocky shore, the water droplets splash off and become fog-like and enter the air. These suspended liquid particles of chloride in the air are called salt fog. The salt fog forms an electrolyte on insulating and metallic surfaces, accelerating the corrosion process and seriously affecting the insulation performance. For instance, it may cause corona discharge and an increase in leakage current.
The hazards of insects and small creatures
In tropical regions, the harm caused by insects and small creatures is particularly severe. On one hand, they build nests inside electrical machines and leave behind corpses, causing mechanical blockages; on the other hand, they bite through insulation or consume insulation materials, resulting in short-circuit faults. Particularly, termites, wood-eating ants, rats, and snakes are the most harmful.
Corrosive gas
In production sites of the chemical industry (including mines, fertilizers, pharmaceuticals, rubber, etc.), there are mainly a large amount of gases such as chlorine, hydrogen chloride, sulfur dioxide, nitrogen oxide, ammonia, hydrogen sulfide, etc. Although their corrosion is relatively small in dry air (with a maximum relative mixing degree lower than 70%), they will form acidic or alkaline corrosive aerosols in humid air. Generally, when the relative humidity of the air has not reached saturation and there is condensation on the surface of the product, the corrosion of metal parts and components and the deterioration of insulation performance will be greatly accelerated. Therefore, the impact of corrosive gases on motor products depends on the air humidity, the nature and concentration of the corrosive gases.
Barometric pressure
In high-altitude areas (above 1000 meters), due to the decrease in air density as the altitude increases, it affects the increase in motor temperature and the decrease in output. The starting voltage of corona in high-voltage motors will also decrease accordingly. If the motor operates with corona for a long time, it will affect the service life and safe operation of the motor. In addition, changes in altitude have a significant impact on DC commutation and brush wear. In atmospheres lacking moisture and oxygen (especially moisture), the formation rate of copper oxide films on the commutation surface slows down, which cannot balance with the wear, thus leading to deterioration of commutation and an increase in brush wear.
High-energy
High-energy rays (such as electrons, protons or Y-rays from nuclear radiation) can cause the atoms of a substance to shift, resulting in lattice defects and the formation of vacancy-gap atomic pairs, thereby causing radiation damage to the material structure. Additionally, when a substance is exposed to radiation, electrons detach from their orbits, generating hole-electron pairs, which makes the substance prone to ionization. The effect of radiation on insulating materials depends on the type and dose of the radiation (expressed in dose rate or cumulative dose value), the energy spectrum of the radiation, the properties of the irradiated insulating material, and the environmental temperature.Radiation mainly causes damage to insulating materials. Among them, the mechanical properties of organic insulating materials are more severely affected. The allowable radiation dose for insulating materials is 10 roentgens. However, inorganic insulating materials have better radiation resistance, such as quartz and mica, which can tolerate an allowable radiation dose of more than 10 roentgens.
Mechanical force
High pressure, impact and vibration loads can easily cause mechanical damage to the metal components and insulation structures of the motor.
Post time: Jun-12-2025