Introduce
YBX3 series flameproof low-voltage three-phase asynchronous motor
Frame number: H63-400
Capacity: 0.55~560kW
Number of poles: 2~10P
Voltage: 1140v and below
Explosion-proof mark: Exd lIA T4 Gb, Exd IIB T4 Gb, Exd IIC T4 Gb
Machine misalignment vibration characteristics of laboratory and field tests
The purpose of the experiment was to examine the type of vibration signature not exhibited by the centrally-rotating device and the forcing mechanism involved in generating the signal.
Many people working in the field of vibration analysis believe that shaft misalignment can be detected by the following characteristics:
- High frequency component of twice or twice the operating speed
- High axial vibration level
- 180 degree phase difference between the two ends of the coupling
These symptoms can occur when they are wrong, but not always. In a series of tests carried out with rotating machinery deliberately misaligned, and in many field observations on equipment operating under misaligned conditions, four concluding facts can be drawn.
- The severity of misalignment cannot be detected using vibration analysis. In other words, there is no relationship between the amount of misalignment and the level or amplitude of the vibration.
- Different flexible coupling designs will make the vibration characteristics of the misaligned rotating machinery different. For example, a misaligned gear coupling will not display the same vibration pattern as a misaligned elastic rubber ring type coupling.
- The misalignment vibration characteristics of the mechanical rotor supported in the sliding bearing are usually different from the vibration characteristics of the mechanical rotor supported in the rolling bearing.
- The vibration characteristics of the misaligned flexible coupling usually have a multiple of the running speed. As mentioned earlier, it only makes sense to measure the phase if the main vibration occurs at the operating speed. If most of the vibration occurs primarily at frequencies other than the operating speed, the phase Angle data is somewhat meaningless.
- Misalignment test of coupling of small rotating equipment in laboratory
- Equipment condition:
Below is a 1/2 HP, 1775 rpm motor that drives a central shaft with two balance plates connected to another external shaft with a cantilever type balance plate. The three axes are connected together using a flexible disc coupling.
2, vibration measurement:
The unit was almost fully aligned, operated at operating speed, and overall vibration measurements were made for all six bearings. Then stop, loosen the bolt holding the intermediate shaft to the frame, the intermediate shaft is misaligned 31mils (0.78mm) on the side, lock in that position, turn on, and measure the vibration, proximity probe gap reading, and amperage. Turn off the machine again, loosen the bolts that hold the intermediate shaft to the frame, the intermediate shaft is offset to the side by 31mils (0.78mm) (now a total of 62mils (1.56mm) to the side), lock in the position, turn on, and make a final vibration measurement.
3, vibration, rotor deformation, power consumption measurement results：
In almost all cases, the vibration level decreases as the dislocation increases. Current consumption hardly changes from run to run. However, the distance between the approach probe and the balance disc increases almost in proportion to the misaligned amount. This verifies that the elastic bending of the shaft does indeed occur in a situation similar to the figure below.
Second, field test the vibration characteristics of motor driven pump under various misalignment conditions
- Equipment condition
The figure below shows a 60 HP, 1775 rpm motor and circulating water pump connected by a metal ribbon coupling as shown in Figure 2.17 that is deliberately misaligned (lateral) by 21 and 36 mil and vertically by 55 and 65 mil. A total of seven test runs were carried out under various alignment conditions.
The vibration analysis equipment used in the test, using a handheld vibration meter with an accelerometer sensor, collected vibration data at five points of each unit to record the overall reading of the bearing box. A vibrometer with a magnetic base is also attached to each sensor location, and signals are fed into the analyzer and X-Y plotter to record vibration characteristics.
Since the motor housing is of aluminum construction, a ¼ inch thick carbon steel plate was bonded to the motor with epoxy resin on the horizontal and vertical sides of the two bearings, and another plate was attached to the inside end cover to capture axial vibration levels.
2, seven times the coupling misalignment operation
- Run #1 (motor uncoupled, run separately). The first run is performed with the motor uncoupled to determine if there is an unbalanced condition of the motor, bearing damage, or other issues that may affect the vibration response when coupled to the pump.
- Run # 2M2W. The pump and motor are initially well aligned within acceptable alignment tolerances.
- Run # 3M21W. The motor was located 0.021 inches to the west, and no shims were added or removed from the pump or motor during the second run.
- Run No. 4 M36W (motor to the west 36 mil). During this run, an attempt was made to slide the engine further west. However, the motor was jammed with bolts and could not move further sideways.
- Run #5 M65H (motor height 65 mil). The motor is now well positioned from side to side, but 0.065 inches higher than the center line of the pump shaft
- Run #6 M55L (motor low 55 mil). In this test run, the motor shaft centerline is set to be significantly lower than the pump shaft centerline, while still maintaining good left-right alignment.
- Run #7 M6W (Motor-6 mils west). Align the pump and motor again within acceptable alignment tolerances (similar to the second M2W run) to determine if the vibration response at the bearing will repeat.
3, seven times running bearing box overall vibration level
The overall vibration results of seven test runs are shown in the figure. Note that in each trend, the overall vibration increased only slightly, and in some cases slightly decreased, due to equipment misalignment of 21 and 36 mil. In some cases, when the device is in the maximum misalignment state (65 mil), the vibration drops from the level of 55 mil.
During the 7th run, the overall vibration level of the pump and motor was largely the same as during the 2nd run, where the alignment conditions were nearly the same, verifying that the vibration was caused by misalignment and other factors.
The following is: motor outside, motor coupling side, water pump coupling side, water pump outside bearing vibration; The horizontal coordinate is the degree of dislocation of the coupling
What are the installation procedures and processes of the pump motor
Common problems:
1, the pump motor power tube fixed unreasonable; The metal hose is more than 80cm long, and it is easy to rust without waterproof metal hose.
2, the pump suction pipe diameter reduction using concentric or eccentric connection, easy to produce air bags.
3, water pump inlet and outlet pipe back elbow, without shock absorption directly fixed, no shock absorption measures and not conducive to pipe disassembly and installation.
4, the base screw installation is unreasonable. (Flat gasket, spring sheet, bolt exposed 1~3 wire, no anti-corrosion measures.)
General process of pump house engineering
Water pump foundation → Water pump installation → Pipe and support installation → Wiring and grounding installation → Ground and gutter → support root end → Marking
Pump house engineering related specifications
Requirements of the Code for Acceptance of Construction Quality of Building Electrical Engineering:
14.2.10 The laying of metal and non-metal flexible conduits shall comply with the following provisions:
- The rigid conduit is connected with the electrical equipment and appliances through the flexible conduit, and the length of the flexible conduit is not more than 0.8m in the power engineering and not more than 1.2m in the lighting engineering.
- The connection between flexible metal pipes or other flexible conduits and rigid conduits or electrical installations and appliances is made of special connectors; The joints of composite flexible metal pipes or other flexible conduits are well sealed, and the anti-liquid covering layer is intact.
3, flexible metal conduit and metal flexible conduit can not be ground (PE) or zero (PEN) continuous conductor.
“Compressor, fan, pump installation engineering construction and acceptance code” requirements:
The length of the straight pipe section before the pump inlet should not be less than 3 times the inlet diameter D, and the length of the reducer pipe before and after the pump should not be less than 5 to 7 times the diameter difference of the size of the pipe; The inlet diameter of the pump adopts eccentric top flat connection, and the outlet adopts concentric diameter connection.
Requirements of “Construction Quality Acceptance Code for Building Water supply and Drainage and Heating Engineering” :
3.3.15 The pipe interface should meet the following requirements: the diameter and length of the bolt connecting the flange should meet the standard, after tightening, the length of the protruding nut should not be greater than 1/2 the diameter of the screw.
Key processes:
- The equipment foundation must be carefully positioned and lofted, the ground wire and power pipe should be embedded in place before the floor construction, and the surface of the foundation should be painted and polished in advance before the equipment installation to prevent the middle part from closing after the equipment installation, and the painting surface layer from covering the equipment vibration damping pad.
- The U-PVC gutter around the equipment and the magnetic sheet around the gutter are buried first, and then the ground concrete surface layer is constructed.
Install the motor power tube on the ground, waterproof bend the equipment power tube, ground jumper of the equipment and power tube, and handle the base bolt closure.
Bridge into the motor power supply practice: custom cable lead down 45 degrees design clever installation specifications.
Characteristics of the pump motor
- Pump type load introduction
The special motor for pump load has two application structures, horizontal and vertical, and has three technical characteristics: relatively small starting torque, relatively small starting frequency, and relatively long continuous running time.
Usually, the pump motor is mostly an asynchronous motor or synchronous motor of the squirrel cage rotor, and the motor power is greater than the shaft power of one grade, and the number of motor poles is closely related to the lift and flow of the pump. If the shaft power is 22kW, choose 30kW motor; 2-pole motor is generally used in the case of slightly high head and little flow; 4 pole motor can be selected for large flow and small head; Choose 4 or 6 pole motors with large flow and low head.
- Pump motor connection
According to the scope of application of different applications, applicable places and economic factors, etc., there are the following ways to connect the pump and the motor:
1.The shaft of the pump is directly connected with the motor shaft;
2.The shaft of the pump is connected with the motor shaft through a coupling;
3.The shaft of the pump is connected with the motor shaft through the reducer box;
4.The shaft of the pump is connected to the motor shaft by the hydraulic coupler.
- load characteristic
The load of pump motor is related to the lift and flow of pump. When the high head pump works at the high head point, its flow is the flow of the design point, when the low head work, equivalent to the pump outlet resistance is reduced, then the flow of the centrifugal pump will increase, the pump motor will be overloaded, and it will burn the pump motor to a certain extent.
- Motor overcurrent prevention
Avoid equipment overload operation, so that the pump power for a long time at the rated current or excess current operation. Because the starting current of the pump motor is 3-5 times the rated current, special attention should be paid to avoid starting the device with load or full load.
The pump motor works in a humid working environment. Before starting the pump motor, the coil insulation to the ground and insulation between phases should be checked, and the water and moisture resistance of the pump motor should be paid attention to during the operation of the pump motor.
Strengthen maintenance, reduce pump motor overload caused by mechanical failure of the pump.
Monitor the winding temperature of the pump motor in real time to avoid the burning accident caused by the failure of the cooling system. General pump motor coils are air-cooled shell, submersible pump is water-cooled shell. The large pump motor is cooled by air-air heat exchanger and air-water heat exchanger. If the cooling medium is broken, so that the coil can not dissipate heat, it may burn the coil.