JB/T 6228-1992 Inspection method and evaluation of internal water system of turbine generator windings
Some standard content:
Mechanical Industry Standard of the People's Republic of China
Internal water system of steam turbine generator windings
Inspection methods and assessment
Subject content and scope of application
JB/T6228-92
This standard specifies the inspection items, methods and quality assessment requirements for the sealing and flowability of the internal water system of the water-cooled windings of steam turbine generators.
This standard is applicable to the inspection of the manufacturing process of double-water internal cooling and water-hydrogen-hydrogen type steam turbine generators, and is also applicable to the inspection of the handover acceptance and overhaul process of the unit.
Division of inspection methods
Sealing test
Flowability test
3 Water pressure test method
Water pressure leak detection method
【Gas leak detection method
Water flow measurement method
Gas flow measurement method
Standard block method
Stator winding heating test
Hot water flow test
Forward and reverse flushing method
3.1 This test is applicable to the cooling water channel sealing test of wire rods or windings. 3.2 Equipment and instruments
Pressure test (0~35MPa);
b.Precision pressure gauge;
c.Accessories such as pipes, flanges and valves.
3.3 Test method
3.3.1 Before the test, the inspected joints and pipes, valves and other accessories can be tested with penetrant leak detection. 3.3.2 Use a pressure test pump to flush clean water into the cooling water circuit and discharge air at the high water level of the cooling water circuit. 3.3.3 During the water pressure test, the air must be discharged several times to reach the specified pressure and stabilize it, reduce or even eliminate the gas in the water, so as to prevent the pressure fluctuation caused by temperature changes and affect the judgment of water pressure leak detection. 3.4 Inspection requirements
3.3.1 Stator
3.4.1.1 The inspection requirements during manufacturing, unit handover acceptance and overhaul are specified in Table 1. Approved by the Ministry of Machinery and Electronics Industry on June 16, 1992 300
Implemented on January 1, 1993
After the upper and lower wire rod water joints are welded
After the coil is installed with the insulated water pipe
Factory inspection
Unit acceptance
Replace the entire insulated water pipe
Replace part of the insulated water pipe
Overhaul preventive test
JB/T6228-92
The inspection at the power plant site should include the assembly of the stator and the inner end cover, and after connecting the inlet and outlet pipes of each part, check whether there is leakage caused by the installation process under the specified leak detection pressure. 3.4.2
The inspection requirements for the rotor during manufacturing, unit acceptance and overhaul are shown in Table 2. Table 2
Before insulation of copper wire package
Wire embedding (after welding water joint) Baking and pressure collapse
After baking and pressure
Insulation water diversion supervision package Before insulation
Factory inspection
Unit handover acceptance
Replacement of all insulated water diversion pipes and minor repairs
Replacement of local insulated water diversion pipes
Not covered with small guard ring
With small guard ring
Not covered with small guard ring
With small guard ring
50, 60
3.4.2.2 When conducting water pressure test in power plant, the pressure should rise slowly to avoid sudden pressure increase. MPa
Carefully check the seal of the water inlet end face of the rotor to avoid misjudgment of rotor leakage due to water seeping into the interlayer between the shaft and the center tube. When using nitrile rubber insulated water pipes, water should be filled for 1 hour before the water pressure test, and the insulated water pipes, joints and welding parts should be carefully checked for water seepage. 3.4.3 Components
3.4.3.1 Stator insulated water pipe
Use the hot and cold water pressure method: that is, at room temperature, the water pressure is 2.5MPa, and the duration is 0.25h; then the water pressure is reduced to 0.6MPa, the temperature is increased to 90℃, and the temperature is kept at this temperature for 2h.
3.4.3.2 Rotor insulated water pipe
Use the water pressure leak detection method, and the test pressure and time are as follows: for power 100MW and below, the water pressure is 7MPa and the time is 1h; 301
JB/T6228-92
Power 125MW and above, the water pressure is 12MPa and the time is 1h. 3.4.3.3 Main water pipe
Use water pressure leak detection method, test water pressure is 3MPa, time 2h. 3.5 Assessment requirements
During the water pressure test, the pressure gauge is required to have no obvious pressure drop, and there is no leakage at the hand-molded weld joints and flange connections. If the gauge fluctuates due to the influence of the ambient temperature difference and cannot be accurately judged, the test time can be extended until the gauge pressure stabilizes. 4
Gas leak detection method
This test is another method to test the sealing of the cooling water circuit of the wire rod or winding, and this method can be used to test the water pressure leak detection method. Equipment, instruments and materials
Penetrant Bx solution (concentration 30%);
Halogen leak detector:
U-type mercury column differential pressure gauge or precision pressure gauge;
Thermometer:
Atmospheric pressure gauge;
Freon F12 or F2;
Nitrogen or dry compressed air;
Test pipeline and accessories such as gates.
Test requirements
If there is residual water inside the container to be tested, it must be blown clean with filtered compressed air and dried. The compressed air filled into the container must be dried and filtered through an oil-water separator, a dryer and a filter. The sealing structure and materials used during the inspection should be consistent with the structure and materials used in the product. During the airtight test, the air inlet valve should be closed tightly, and it is not allowed to add gas to the container under test. If necessary, the gas source can be separated. When the airtight test uses a U-shaped mercury column differential pressure gauge, the U-shaped mercury column differential pressure gauge must be placed vertically. When the mercury column appears concave or convex, the reading should be based on the top line of the surface or the bottom line of the concave surface. 4.3.6 As many temperature measurement points as possible should be set around and inside the container under test, and their average temperature should be used as the temperature for calculating the leakage rate. 4.3.7 The difference in ambient temperature between the end of the test and the beginning of the test should be as small as possible. During the test, the container to be tested should be prevented from being heated locally (such as in direct sunlight) or cooled locally (such as placed at the vent). 4.4 Test method
4.4.1 Rough inspection: Fill the tested part with nitrogen or dry compressed air to the leak detection pressure (see Table 3), then apply the penetrant Bx solution on the outer surface of the tested part to check for leaks one by one, and check for bubbles. For parts or parts with strict requirements on insulation resistance values, it is allowed to use anhydrous alcohol for leak detection,
Stator wire help
Fixed line diagram After installing insulating water pipes
Fixed internal water system of the factory
Fixed to the main water pipe
Transfer to Guangneng Group Overspeed Bureau
Note: P% is the rated operating hydrogen pressure.
Double water internal cooling type
Leak detection pressure
Leak detection pressure
Airtight test pressure
JB/T6228-92
4.4.2 Precision inspection: Fill the inspected part with nitrogen or dry compressed air to 0.1MPa, then fill it with a certain amount of Freon, and continue to fill it with nitrogen or dry coal compressed air to detect the leak pressure (see Table 3). Use a halogen leak detector to slowly move on the outer surface of the inspected part to detect leaks one by one. 4.4.3 Airtight test
4.4.3.1 Connect the airtight test pipeline according to Figure B1 in Appendix B. 4.4.3.2 Fill the inspected container with nitrogen or dry compressed air to the airtight test pressure (see Table 3). Start reading after it stabilizes for 2 hours, and record it in Table C1 in Appendix C. Record it every 1 hour thereafter. 4.4.3 .3 12 hours after the start of reading, the formula listed in Appendix A can be used for calculation. If the calculated leakage rate meets the assessment requirements for three consecutive points (see Article 4.5.3), and its fluctuation (maximum value minus minimum value)/average value) does not exceed 15%, the test can be terminated. 4.5 Assessment requirementswwW.bzxz.Net
4.5.1 Rough inspection: There should be no bubbling at the inspected welds or joints within 15 minutes. 4.5.2 Fine inspection: When using a full-scale inspection instrument, the leakage amount of Freon in the atmosphere; for water-hydrogen cyanide type generators, it should not exceed 1×10-*cm/s; for double-water internally cooled generators, it should not exceed 1×10-4cm/s. 3 Airtightness test: The leakage pressure drop AP for 24 hours is ≤0.2%P, that is, the leakage rate 8 for 24 hours is ≤0.2%, where PI is the starting pressure drop. Test pressure 4.5.3
5 Water flow measurement method
5.1 This test is applicable to the flowability inspection of the cooling water path of the wire rod or winding. 5.2 Equipment and instruments
Pressure gauge (0~0.6MPa)
Water tank, connecting pipe, flange and valve and other accessories;.
Measuring cup, stopwatch or flow meter (glass rotor flowmeter). 5.3 Test method
Fill the cooling water path of the inspected piece with clean water, and stabilize it at a certain water pressure value (given range 0.05~0.15.3.1
MPa) under the circulation state.
2 Use a measuring cup to measure the water flow rate of each inspected piece within a constant time (not less than 15s), or measure it with a flow meter. 5.3.3 Record the flow value according to the number of the inspected part. 5.4 Evaluation requirements
Single hollow copper wire of stator: randomly select 10 copper wires, whose flow does not exceed ±10% of the average value and meets the design requirements; stator wire rod (after welding water joint): does not exceed ±10% of the average flow of the entire wire rod; after welding water joints of the upper and lower layers of the stator: does not exceed ±10% of the average flow of the entire wire rod; before rotor drying and pressing: the flow deviation of the same-sign coils at each pole is less than or equal to 20%; after rotor drying and pressing: the flow deviation of the same-sign coils at each pole is less than or equal to 20%. 6 Gas flow measurement method
This test is another method to test the flowability of the cooling water path of wire rods or windings. 6.2 Equipment and Instruments
Pressure air source (0.4~0.6MPa);
Filter dryer;
Air storage tank;
A27W-10J spring-loaded safety valve;
Pressure reducing valve:
Stability tank:
Air valve:
Pressure gauge;
Air flow tester,
6.3 Test method
Air flow test device The arrangement is shown in Figure 1:
JB/T6228-92
1-pressure air source: 2-filter dryer; 3-air storage tank: 4-spring safety valve; 5-pressure reducing valve: 6-pressure stabilizing tank; 7-air valve; 8-tested workpiece + 9-air flow tester; 10-precision pressure gauge 6.3.2 Connect the air inlet end of the air flow test device to the pressure air source, connect one end of the tested workpiece to the pressure stabilizing tank, and the other end to the air flow tester.
6.3.3 Open each air valve in the test device to allow clean and dry air of a certain pressure to flow into the tested workpiece. 6.3.4 Under the circulation state, adjust the pressure reducing valve so that the pressure in the pressure stabilizing tank is stabilized at the value specified in Table 4 according to the different tested workpieces.
Single hollow copper wire before conductor transposition
Single hollow copper wire after conductor forming
Stator coil
Pressure in the pressure regulating tank
6.3.5 Record the value displayed by the air flow tester, which is the actual air flow of the workpiece being tested. 6.3.6 Record the flow according to the number of the workpiece being tested. 6.4 Assessment requirements
Each manufacturer shall determine the air flow value that the workpiece being tested should reach according to the specific situation of the product structure. 304
Not specialized for the industry
Standard block method
JB/T6228-92
7.1 This test uses compressed air with a pressure of 0.4~0.6MPa to blow the standard block so that it passes through the entire length of the copper wire to measure the fluidity of the single hollow copper wire of the rotor.
7.2 After the copper wire is annealed but before winding, the single-side gap between the standard block and the inner hole of the copper wire shall not exceed 0.35mm. 7.3 After the copper wire winding welding is completed, the standard block is a sphere, and the single-side gap between the inner hole of the copper wire and the sphere shall not exceed 0.50mm. 8 Stator winding heating test
8.1 This test is applicable to determine whether there is blockage in the internal cooling water path of the stator coil of the steam turbine generator and the welding quality at the nose joint of the stator winding.
8.2 Equipment and instruments
Low voltage, high current DC generator set; ammeter;
voltmeter:
eliminating thermometer or thermal imager;
flowmeter;
pressure gauge.
8.3 Test method
8.3.1 This test is carried out after the stator winding is connected to the insulating water pipe but before it is insulated. The test circuit is shown in Figure 2. B
8.3.2 Cooling water is passed through the stator winding, and the flow and pressure are adjusted to the rated or close to the rated value. After the three-phase winding is connected in series, low-voltage direct current is sent to the rated value. If the equipment capacity is limited, it can be carried out in phases. 8.3.3 After 15 minutes of power-on, touch the insulated water pipe at the water outlet of each coil and the nose of the stator winding with your hand, and bury several alcohol thermometers at higher or lower temperatures (or use an infrared thermal imager to directly detect the temperature of each part). 8.3.4 Read the current, voltage, flow, inlet and outlet water temperature and the temperature of each measuring point every 10 minutes. 8.3.5 After the test for 1 hour, compare the temperatures of each water outlet joint and insulated water pipe. If there is a significant difference in temperature, the machine should be shut down first, the water should be cut off, and then the insulated water pipe joint should be disassembled for inspection. 8.4 Assessment requirements
The temperature difference between each coil is not greater than 8K.
9 Hot water flow test
JB/T6228-92
9.1 This test is applicable to the general assembly or overhaul of the steam turbine generator to check whether there is serious water blockage in any part of the internal water system of the stator of the steam turbine generator.
9.2 Equipment and instruments
Imin);
Copper-Kang thermocouple:
Temperature recorder (the minimum grid value is 0.1C, the number of channels is greater than the total number of thermocouples to be measured, and the patrol time for one week is less than the hot water flow test equipment (it can also be replaced by the generator external water system device). 9.3 Preparation before the test
9.3.1 Use glass ribbon to tie the thermocouple node to the outer surface of the middle section of the insulated water pipe at the water outlet end. Each insulated water pipe must be equipped with a thermocouple on the surface.
9.3.2 Wrap each thermocouple with insulation material to ensure that the thermocouple is isolated from the surrounding air. 9.3.3 Connect the thermocouple to the temperature recorder point by point and check the uniformity of the thermocouple readings 9.4, Test method
9.4.1 Start the hot water flow test equipment or the stator external water system device, adjust the pressure difference between the stator inlet and outlet main water pipes to the normal operating value, and measure the cold water temperature of each measuring point at this time.
9.4.2 Through self-circulation and auxiliary steam heating, heat the test water to at least 10C higher than the cold water temperature. 9.4.3 When the temperatures of all measuring points are close, stop the operation of the hot water flow test equipment or the stator external water system, turn off the steam and record the temperature readings of each measuring point at the same time.
9.4.4 Maintain the shutdown state for 30 minutes, and record the temperature reading every 5 minutes during this period. 9.4.5 After the shutdown state ends, quickly open the cooling water valve to allow cooling water to flow through the stator internal water system. Start the water Pump and keep the pressure difference of the stator internal water system during normal operation, record the temperature reading at the same time, and then record the temperature reading every 1 minute. 9.4.6 After the water circulates for 15 minutes, when the temperature of the thermocouple measuring point tends to be stable, stop the operation and the recording of the thermocouple temperature. 9.4.7 Organize the data and draw the time (t)-temperature (0) curve of each insulating water pipe. 9.5 Assessment requirements
Compare the time (t)-temperature (0) curves of each insulating water pipe·Figure 3 and Figure 4 clearly show whether there is cooling water passing through the insulating water pipe, (c)
101214
Figure 3 Normal water flow
r(min)
8 City 12
Figure 4 Water blockage|| tt||(min）
9.6 Precautions
JB/T6228-92
9.6.1 This test must be carried out after the internal water system of the stator has been flushed. 9.6.2 When all coils have been subjected to the hot water flow test and the data has been plotted into a curve, the temporary thermocouples shall be removed from the insulated water pipe after being checked and qualified by the test personnel.
9.6.3 When the number of channels of the temperature recorder is insufficient, it can be carried out in groups, but the number of groups shall not exceed three groups. Each group of tests shall repeat 2~3 thermocouples in the previous group of tests.
When some results are in doubt, the water temperature may be appropriately increased and retested. 10 Positive and negative flushing method
This method is suitable for improving the flow of the winding cooling water path during the overhaul of the power plant. 10.2
Before flushing, drain the accumulated water in the internal water system of the stator and rotor, and blow away the remaining water with 0.3~0.5MPa compressed air. 10.3 When flushing, clean condensate water is introduced, and compressed air of 0.3-0.5MPa is used to repeatedly flush forward and backward from the water inlet and outlet of the water system until all dirt is removed and the water flow is clean. 1 If necessary, high-pressure nitrogen and oxygen can be used for flushing, or even acid washing and descaling. 10.4
A1 Symbols
P, - test start gauge pressure, MPa;
P-——test end gauge pressure, MPa;
B, test start atmospheric pressure, MPa;
·test end atmospheric pressure, MPa;
test start average temperature, C;
test end average temperature, C;
APa--24h leakage pressure drop, MPa;
A test duration, h;
8-.-24h leakage rate, %.
Calculation formula
JB/T6228--92
Appendix A
Airtightness test calculation formula
(Supplement)
AP=24/△[(P,-P)+(B,—B)+(P+B,)(t2—t:)/(273+t,))=△Pa/P,X100%
（A1）
（A2）
JB/T6228—92
Appendix B
Schematic diagram of airtight test pipeline connection
(reference)
The schematic diagram of airtight test pipeline connection is shown in Figure B1. Inlet
Moisture separator
Dryer
Youhuli Bureau
Type poly-column differential pressure gauge
The airtight test record form is shown in Table C1.
Test time
Additional instructions:
Test pressure
JB/T6228—92
Appendix C
Airtight test record form
(reference)
This standard is proposed and managed by Harbin Large Electric Motor Research Institute of the Ministry of Machinery and Electronics Industry. This standard is drafted by Shanghai Electric Motor Factory and Harbin Electric Motor Factory. The main drafters of this standard are Chen Jintang, Yuan Changming and Ge Chenzhong. 310
Atmospheric pressure
Cumulative pressure difference
Air leakage rate
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