Centrifugal fans are used in many public facilities. Under normal circumstances, corresponding maintenance and maintenance will be carried out after a period of use. In order to ensure that the maintenance and maintenance of the fan in the later use is simpler and faster, it needs to be installed after the completion of the installation. After commissioning and debugging, the following editors have sorted out the test sequence and precautions of the centrifugal fan for your reference.
1)Test sequence of centrifugal fan
1. Trial operation of oil lubrication system
The oil lubrication system is the primary condition to ensure the normal operation of the centrifugal fan. Large centrifugal fans have a relatively complete oil lubrication system. Before the official commissioning, the first trial operation of the oil lubrication system must be carried out. Through the oil circulation, the rust, welding slag and scale in the oil pipeline and oil cooler can be cleaned, the sensitivity and reliability of the safety valve, automatic control and interlocking device of the oil system can be adjusted, and at the same time, the oil pump can be checked to see if the oil system is working properly. Whether the pipeline is tight and whether there is oil leakage or air leakage.
2. The single test run of the motor
The trial operation of the motor is mainly carried out by electrical personnel. Before the trial operation, first loosen the pins and nuts of the coupling between the motor and the centrifugal fan, and turn the rotor of the motor. It should be flexible and no noise.
(1) Instantly start to check whether the rotation direction of the motor is correct, whether the sound of the motor is normal, and whether there is impact or collision.
(2) Run for 30 minutes. Check the noise, vibration and temperature rise of the motor during operation. According to regulations, the temperature of the stator should not exceed 75 degrees, and the temperature of the bearing should not exceed 65 degrees.
(3) Continue to run for another 4 hours, comprehensively check the operation of the motor and various test data, and only after passing the appraisal of relevant personnel can the next stage of trial operation be carried out.
3. No-load test run of centrifugal fan
After the motor test run meets the requirements, the centrifugal fan can be linked to carry out the no-load test run of the motor-centrifugal fan linkage. Usually, the inlet valve of the centrifugal fan is closed, and the outlet pipe is disassembled. In the absence of any resistance The test run is usually carried out with air as the medium, and the running time is 4 hours. The test run sequence is as follows:
(1) Instantaneous start to check whether the internal noise of the centrifugal fan, gear box, etc. is normal, whether there is friction between the rotors of the centrifugal fan, the vibration of the centrifugal fan, and whether the oil supply of the oil lubrication system is normal.
(2) After running for 30 minutes, check the running sound of the centrifugal fan and motor, and there should be no abnormal noise; measure the vibration value of the centrifugal fan every 10 minutes, and observe whether there is any change; comprehensively check the oil supply, and detect the oil temperature and oil pressure and bearing temperature, as well as unit operation.
(3) Continuous operation for 4 hours. Check whether the cooling water is smooth and whether the water pressure is stable; check whether the automatic control systems and signal indications are correct and sensitive; comprehensively check the operation of the centrifugal fan unit and its auxiliary pipelines.
4. Centrifugal fan load test drive
The contents of the centrifugal fan load test run are as follows:
(1) Preparation and start of the test run, the load test time is 8 hours, and all the medium of the test run is air. Before the test run, sufficient preparation should be made, and the problems existing in the no-load test run should be carefully checked and dealt with.
(2) Loading step, after starting the operation with no load for 10-30 minutes without any problem, you can start the load test. During the test, slowly close the outlet valve of the centrifugal fan to gradually increase the pressure.
(2) The inspection items in the load operation are the same as those in the no-load trial operation, and an operation record is made every 30 minutes.
(4) After the load trial operation is completed, a comprehensive inspection of the centrifugal fan should be carried out.
2) Precautions for the test run of centrifugal fan
1. Centrifugal fans can be started with full pressure or reduced pressure, but when starting with full pressure, it is necessary to ensure that the capacity of the power grid is sufficient. Because the current at full voltage startup is five to seven times the rated current, if the capacity of the grid is insufficient, the form of step-down startup should be used.
2. Generally, when the fan with motor power above 7.5KW starts, it is recommended to use star-delta step-down starting, or use variable frequency motor to start gradually from 0-50HZ, which has less impact on the power grid.
3. When the centrifugal fan is commissioned, be sure to read the product manual carefully, especially to check the circuit condition. Because the centrifugal fan is in the test run, if there is a fault on the circuit, it will directly cause the failure of the fan.
4. Before the test run, check the coplanarity of the pulleys, that is, the pulleys of the motor and the fan should be on the same plane. A ruler can be used on site, and the ruler is close to the side end face of the pulley of the motor or fan, and the pulley is rotated. Observe that the ruler is in line (same face) with the other pulley.
5. While adjusting the flatness, it is necessary to adjust the tension of the belt. The tightness of the belt has a critical influence on the operation effect of the fan. Too loose or too tight is not good. Strict operation needs to be adjusted according to the span and specification of the belt, according to a certain tension range.
6. During the test run of the centrifugal fan, there must be no less than two people. One person controls the power supply, and the other person observes the operation of the fan. If an abnormal condition occurs during the working process of the centrifugal fan, such as the fan reverses. Be sure to stop the fan in time. Then check whether the data of the fan is normal in all aspects. After the inspection is completed, it will take at least five minutes or the fan will stop completely before it can be started again.
7. Even if the centrifugal fan is running normally, it should be measured whether the input current of the fan is normal. If the test current exceeds the rated current, stop the machine, and then measure the data in various aspects. Because there must be a reason for exceeding the rated current, it may affect the use effect of the fan.
8. When the fan is running, if the running current of the motor exceeds 20% of the rated value of the motor, you must be very careful. At this time, it is easy to burn the motor if it runs for a long time.