Motor on a net, although it is not a uniform mass around, but the basic characteristics of the heating process is generally applicable to motor. In order to make the motor temperature rise is not beyond must value, must on the one hand, reduce the loss of the motor of motor on the other hand is to add heat to. Along with the motor capacity increasing, improve the cooling system, advances the cooling ability to limit the rise of temperature of the motor, has been the process of motor development and progress of one of the main problems. When motor under must have the capacity of the normal operation, the temperature rise is also a must. Therefore, as long as the rules of the temperature rise of the motor, to make the motor capacity of exact significance. The intention of the temperature rise of accounting is accounting in the motor temperature rise in the operation of several heating components in additional to whether allow beyond limit value, and considering the necessary margin, Ms. Today they temperature topic sharing with you for a simple. Concluded that the principle of the motor temperature rise limit in the condition of extra long time operation and to stabilize its temperature, the temperature rise of the motor parts agreed to limit called temperature limit. Motor temperature rise limits in the national standard, there are rules, the heat level corresponding to different temperature increment. In terms of winding, the temperature rise limit basically depends on its insulation structure to the highest temperature and the temperature of the cooling medium, but also and temperature measurement method, heat transfer and heat conditions of the winding and the promise of factors, such as heat flow strength now respectively to clarify as follows: low motor winding insulation structure chosen materials, under the action of temperature, the mechanical, electrical, physical, and other functions will gradually deteriorate, surely when the temperature rises to the level, the characteristics of insulation materials will attack substantial changes, and eventually lose insulation ability. In the electrotechnics, often from the motor and electrical insulation structure or the system is divided into several heat resistant grades according to the limit temperature. Insulation structure or system under the temperature of the corresponding level for a long time, generally do not function of qualitative change. Low insulation structure under the limit temperature of rules, can obtain the use of comparative economic life. Theoretical derivation and the practice has proved that the application of insulation structure between life and temperature is exponential relation, thus it is very sensitive to temperature. If the temperature of each 8 - beyond the limit temperature14 ℃, its use life will be shorten half uniform. About some special purpose machine, as its use does not require a long service life, then in order to narrow the volume of motor, according to the experience or experimental data for progress motor's promise to limit temperature. When the temperature of the cooling medium although along with the cooling system and cooling medium varies, but for now to choose a variety of cooling system, the temperature of the cooling medium basically depends on the atmospheric temperature, and on the numerical and atmospheric temperature is approximately the same. But air temperature with different time in a year and address change, according to the statistics, our country in uniform temperature are below 22 ℃, uniform are no more than 35 ℃, the highest temperature 35 ~ 40 ℃ and certainly the highest temperature is in commonly between, as long as a few area between 40 ~ 45 ℃. Now most countries around the world generally choose the highest temperature area atmosphere must be as the temperature of the cooling medium, and China's national standard rules + 40 ℃ as the temperature of the cooling medium. Low temperature measurement method is different, can cause the temperature of the measured with the unit under test in the difference between the hottest temperature is different also, and the temperature is the most popular of the unit under test to judge the key of the motor can run safely for a long time. Under general conditions, temperature limit is not beyond 1000 meters above sea level, the highest temperature of 40 ℃ regional rules. In the area of higher altitude, the air is thin and poor heat dissipation condition, a motor is running under this condition, the temperature in the national standard rules, when the motor using address elevation above the test conditions to calculate. Especially under the condition of temperature rise limit under some special conditions, the handling of the motor winding temperature rise limits are often not totally depends on the structure of the promise the highest temperature, but also consider other factors: low further progress of the motor winding temperature generally means the increase of motor loss and efficiency drop, the economically must not economical. The progress of low temperature of the winding,For example, higher than 150 ℃), may cause bearing smooth system operation difficult, etc. About with the motor commutator, the progress of the winding temperature (For example, higher than 200 ℃)Would cause the difficulty of reversing the progress of the winding temperature will cause some related spare parts information and guess the increase of the thermal stress. Other, such as the insulation dielectric function, the metal conductor material mechanical strength and so on, will bring adverse impact. Thus, although now some motor winding with class F or class H insulation structure, but its temperature limit often still according to the rules of class B value, this not only considering the above factors, and about to add the reliability of the motor used in favourable, and can extend the motor life.
