Freeze Dried process is a method to freeze the dry liquid materials into solid and use the sublimation properties of ice under low temperature and pressure to dehydrate the materials and achieve the purpose of drying. Freeze-drying technology first appeared in the space field, and it is known to all that the space food has a high quality requirement, which is designed to meet the needs of the astronauts in space for the nutrition of fruits and vegetables. Because freeze-drying technology not only let the color, aroma, taste, nutrition of the food itself, but also make food more convenient to carry and transport. With the development of economy, freeze-drying technology has been applied to daily food processing, so the lyophilization process is also called aerospace food technology.
Freeze dried food is to use rapid freezing, vacuum dehydration method of ice, preserved the original color, aroma, taste, nutrition, and the appearance of the original material, the water content of only about 5%, because of the particularity of its craft, by freezing to break the cell wall, so crispy, nutrition, easy absorption
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1. To keep the clean motor of the motor in operation, dust, water stains, and other sundries must not be allowed within at least 3 meters around the air inlet to prevent inhalation of the motor interior, the formation of a short circuit medium, or damage to the wire insulation layer, resulting in a short circuit between the turns. Current increases, temperature rises and the motor burns. Therefore, to ensure that the motor has sufficient insulation resistance, as well as a good ventilation and cooling environment, in order to enable the motor to maintain a safe and stable working condition in long-term operation.
2. Keeping the motor running at rated current often causes the motor to run overloaded. The main reason is that the motor is overloaded due to drag, the voltage is too low, or it is caused by mechanical locking. If the overload time is too long, the motor will absorb a large amount of active power from the power grid, the current will increase sharply, and the temperature will rise. At high temperatures, the insulation of the motor will deteriorate and burn out. Therefore, when the motor is in operation, it is necessary to pay attention to checking whether the operation of the transmission is flexible and reliable; whether the concentricity of the coupling is standard; the flexibility of the gear transmission, etc. If any stagnation is found, the machine should be shut down immediately to identify the cause of the failure. Then run it again.
3. Always check whether the motor three-phase current balances the three-phase asynchronous motor. The difference between the three-phase current of any one-phase current and the average of the other two-phase current must not exceed 10%, so as to ensure the safe operation of the motor. If it is exceeded, it means that the motor is faulty, and the cause must be identified and eliminated.
4. Check the motor temperature should always check the motor bearing, stator, housing and other parts of the abnormal temperature changes, especially for no voltage, current and frequency monitoring and no overload protection of the motor, the temperature rise is more important to monitor. Whether the motor bearing is overheated or lacks oil, if it is found that the temperature rise near the bearing is too high, it shall be immediately checked for shutdown. Whether there are cracks, scratches, or defects in the surface of the rolling element or raceway of the bearing, whether the bearing clearance is excessively swaying, and whether the inner ring rotates on the shaft. If any of the above phenomena occurs, the bearing must be renewed before it can be reworked.
5. Observe the motor for vibration, noise and abnormal odor. If the motor vibrates, it will cause the connected part of the load to increase its misalignment, resulting in an increase in motor load and an overloaded operation that will burn the motor. Therefore, when the motor is in operation, especially high-power motors, it is always necessary to check if the anchor bolts, motor end caps, bearing glands, etc. are loose, and the grounding device is reliable. If any problems are found, solve the problem in time.
The noise and odor of the noise field are precursors of the abnormal operation of the motor and serious failures immediately. It must be discovered at any time to find out the reason and eliminate it.
6. Ensure the normal operation of the starting equipment The quality of the motor starting equipment is of decisive importance to the normal starting of the motor. Practice has proved that the vast majority of burned motors are caused by abnormal operation of the starting equipment. If the start-up equipment has a phase-to-phase start, the contactor contacts arc, sparks, etc. The maintenance of starting equipment is mainly cleaning and fastening. If the contacts of the contactor are not clean, the contact resistance will increase, causing the heat to burn out the contacts, causing the lack of phase and burning the motor; the iron core corrosion and dust accumulation of the contactor sucking coil will make the coil suck loose and occur. Strong noise, increase the coil current, burn the coil and cause failure.
Therefore, the electrical control cabinet should be set in a dry, ventilated and easy-to-operate position and regularly dusted. Always check whether the contacts of the contactor, the core of the coil, the wiring screws, etc. are reliable, and whether the movement of the mechanical parts is flexible, so as to maintain a good technical state, so as to ensure smooth start-up work without burning the motor.
6 measures to avoid motor burnout
In the operation of the motor to avoid burning, in addition to taking the necessary technical protection measures before operation, the most effective and practical method of prevention is to carry out the correct technical maintenance. There are mainly 6 points below.