High-voltage motor shaft voltage on-line measurement method and device

Abstract

The invention discloses a high-voltage motor shaft voltage on-line measurement method and device. The device comprises a sampling electrode and a voltmeter connected with the sampling electrode through a wire. The number of the sampling electrodes is two, the two sampling electrodes are connected with the two ends of a motor shaft to be tested respectively, and the voltage difference of the electrode shaft can be obtained through the two sampling electrodes. The voltmeter, the source amplifier, the potentiometer and the control switch jointly form a series loop; shaft voltage values at the two ends of the motor rotor are displayed in real time through the voltmeter, and then an alarm threshold value of the potentiometer is set; when the voltage at the two ends exceeds a preset alarm threshold value, the alarm unit is triggered to give an alarm, an operator only needs to fix the mounting box on the motor through the clamping piece, at the moment, the storage piece is in a relaxed state, and the connecting wire can be freely pulled out of the storage piece; and after connection is completed, the storage piece rolls the connecting wire under the action of the clockwork spring, so that the wire is prevented from being scattered, and the cleanliness of the measuring device is kept.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of shaft voltage measurement, in particular to a high-voltage motor shaft voltage on-line measurement method and device. BACKGROUND

[0002] In thermal power plants, high-voltage motors are one of the important auxiliary machines, and the normal operation of high-voltage motors is directly related to the safety and economy of the unit. Due to the limitation of production process, there will be a slight shaft current in the normal operation process of high-voltage motors. In the daily power production process, sometimes the insulation layer of the bearing bush will be damaged. When the motor fails, the stator will be scanned, and the symmetry of the motor magnetic field will be changed after the motor is stopped for maintenance. After the above defects occur, the high-voltage motor will probably have a large shaft current and shaft voltage during operation. If the shaft voltage is greater than 350mV, it will directly cause obvious electric corrosion to the motor bearing, and then cause the vibration of the motor to continuously increase during operation, and even damage the motor. In order to improve the safe operation of high-voltage motors, it is necessary to monitor the shaft voltage of high-voltage motors to discover and handle equipment defects in time. SUMMARY

[0003] Therefore, the technical problem to be solved by the present application is how to measure the shaft voltage of the high-voltage motor on-line.

[0004] The above technical problem is solved by the following technical scheme: the present application provides a high-voltage motor shaft voltage on-line measurement method, which comprises a sampling electrode and a voltmeter connected to the sampling electrode through a lead wire; the sampling electrode is provided with two groups, and the two groups of sampling electrodes are respectively connected to the two ends of the shaft of the motor to be measured, and the voltage difference of the electrode shaft can be obtained through the two groups of sampling electrodes; the voltmeter, a source amplifier, a potentiometer and a control switch together form a series loop; the shaft voltage values at the two ends of the motor rotor are displayed in real time by the voltmeter, and then the alarm threshold of the potentiometer is set; when the voltage at the two ends exceeds the preset alarm threshold, the alarm unit is triggered to alarm.

[0005] In a preferred embodiment of the high-voltage motor shaft voltage on-line measurement method: the sampling electrode is fixed to the motor end cover through an insulating support, and is used to directly contact the rotor surface to obtain the shaft voltage signal.

[0006] In a preferred embodiment of the high-voltage motor shaft voltage on-line measurement method: the lead wire of the sampling electrode is led out through the motor body temperature measuring element junction box to form a closed measurement loop isolated from the motor rotor.

[0007] To solve the above technical problems, the application further provides a high-voltage motor shaft voltage on-line measuring device, which comprises a high-voltage motor shaft voltage on-line measuring method, and further comprises a mounting box, the inner wall of the mounting box is provided with a containing cavity for placing a voltmeter; the containing cavity is provided with a receiving member and a clamping member, the voltmeter is connected with the sampling electrode through the receiving member; the mounting box is connected with the motor through the clamping member, and the clamping state of the mounting box and the motor can control the receiving state of the receiving member to the connecting lead.

[0008] In a preferred embodiment of the high-voltage motor shaft voltage on-line measuring device, the receiving member comprises a first receiving disc and a second receiving disc, the inner wall of the first receiving disc and the second receiving disc is provided with a clock spring, and the sampling electrode is connected with the voltmeter through the connecting lead respectively penetrating the first receiving disc and the second receiving disc.

[0009] In a preferred embodiment of the high-voltage motor shaft voltage on-line measuring device, the bottom end of the first receiving disc is provided with a clamping rod, the clamping rod is connected with the clamping member through the bottom end of the mounting box; the clamping rod is provided with two groups, which are a first rod and a second rod.

[0010] In a preferred embodiment of the high-voltage motor shaft voltage on-line measuring device, the clamping member comprises a first clamping plate and a second clamping plate connected with the first clamping plate through a reset spring; the first rod is connected with the first clamping plate through the bottom end of the mounting box, and the second rod is connected with the second clamping plate through the moving slot of the bottom end of the mounting box; the second rod can move along the moving slot to adapt to the size of the motor.

[0011] In a preferred embodiment of the high-voltage motor shaft voltage on-line measuring device, the side wall of the mounting box is provided with an opening, and the connecting lead penetrates the opening.

[0012] In a preferred embodiment of the high-voltage motor shaft voltage on-line measuring device, the opening comprises a first hole and a second hole connected with the first hole, the length of the first hole is greater than that of the second hole, the second hole is close to the inner wall of the mounting box, and the first hole is close to the outer wall of the mounting box.

[0013] In a preferred embodiment of the high-voltage motor shaft voltage on-line measuring device, the opening is provided with a blocking member; when there is no external force to pull the connecting lead to the outer wall of the mounting box, the blocking member is used to block the movement of the connecting lead along the opening.

[0014] The beneficial effects of the present application are that, during the measurement process, the voltmeter displays the shaft voltage value at both ends of the motor rotor in real time, and the operator can adjust the potentiometer to set the alarm threshold value as needed. Once the shaft voltage exceeds the preset alarm threshold value, the alarm unit will trigger immediately, realizing timely abnormal monitoring and early warning.

[0015] When it is necessary to measure the shaft voltage of the high-voltage motor, the operator only needs to fix the installation box on the motor through the clamping piece, at this time, the storage member is in a relaxed state, and the connecting wire can be freely pulled out of the storage member; after the connection is completed, the storage member winds the connecting wire under the action of the clock spring, avoids the scattered wire, and maintains the neatness of the measuring device. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present application, but not limit the present application. Among them:

[0017] Figure 1 A use state schematic diagram of the high-voltage motor shaft voltage on-line measurement device is shown;

[0018] Figure 2 A schematic diagram of the insulation support of the high-voltage motor shaft voltage on-line measurement device is shown;

[0019] Figure 3 A schematic diagram of the inside of the installation box of the high-voltage motor shaft voltage on-line measurement device is shown;

[0020] Figure 4 A schematic diagram of the storage member structure of the high-voltage motor shaft voltage on-line measurement device is shown;

[0021] Figure 5 A schematic diagram of the opening cross section of the high-voltage motor shaft voltage on-line measurement device is shown Figure 1 ;

[0022] Figure 6 A schematic diagram of the opening cross section of the high-voltage motor shaft voltage on-line measurement device is shown Figure 2 ;

[0023] Figure 7 A principle diagram of the high-voltage motor shaft voltage on-line measurement method is shown;

[0024] Figure 8 A principle diagram of the sampling electrode of the high-voltage motor shaft voltage on-line measurement method is shown;

[0025] Figure 9 A schematic diagram of the installation of the sampling electrode of the high-voltage motor shaft voltage on-line measurement method is shown.

[0026] In the figure: 1, installation box; 11, containing cavity; 12, opening; 121, first hole; 122, second hole; 2, voltmeter; 3, storage part; 31, first storage disc; 32, second storage disc; 33, clamping rod; 331, first rod; 332, second rod; 34, limiting disc; 35, limiting block; 4, clamping part; 41, first clamping plate; 42, second clamping plate; 43, limiting plate; 44, limiting groove; 5, sampling electrode; 51, insulating support; 52, connecting wire; 6, blocking part; 61, first baffle; 62, second baffle; 63, first plate; 64, second plate; 65, blocking plug; G, motor. DETAILED DESCRIPTION

[0027] In order for those skilled in the art to have a better understanding of the present application, the present application will be further described in detail below in conjunction with specific embodiments and the accompanying drawings.

[0028] The terms used in the present application are those general terms currently widely used in the art in consideration of the functions about the present application, but the terms can be changed according to the intention of those skilled in the art, precedents, or new technologies in the art. In addition, specific terms can be selected by the applicant, and in this case, the detailed meaning thereof will be described in the detailed description of the present application. Therefore, the terms used in the specification should not be understood as simple names, but based on the meaning of the terms and the overall description of the present application.

[0029] REFERENCE Figures 7-9 The present embodiment provides a high-voltage motor G-axis voltage online measurement method, which comprises a sampling electrode 5 and a voltmeter 2 connected to the sampling electrode 5 through a wire; the sampling electrode 5 is provided with two groups, and the two groups of sampling electrodes 5 are respectively connected to the two ends of the motor G-axis to be measured, and the voltage difference of the electrode shaft can be obtained through the two groups of sampling electrodes 5; the voltmeter 2, a source amplifier, a potentiometer, and a control switch together form a series loop; the shaft voltage values at the two ends of the motor G rotor are displayed in real time through the voltmeter 2, and then the alarm threshold of the potentiometer is set; when the voltage at the two ends exceeds the preset alarm threshold, the alarm unit is triggered to alarm.

[0030] Specifically, the sampling electrode 5 is fixed to the motor G end cover through an insulating support, which is used to directly contact the rotor surface to obtain the shaft voltage signal.

[0031] Further, the lead wire of the sampling electrode 5 is led out through the motor G body temperature measuring element junction box, forming a closed measurement loop isolated from the motor G rotor.

[0032] Operation process: first, install carbon brush holders with insulating supports as sampling electrodes 5 at the head end and tail end of the motor G rotor, fix the insulating supports on the motor G end cover through bolts, ensure that the carbon brush vertically contacts the rotor shaft surface, and verify that the insulation resistance is greater than 10MΩ with a megohmmeter;

[0033] Subsequently, the carbon brush lead is inserted into the original temperature measuring element terminal of the motor G body, and is connected to the differential input terminal of the measuring device by using a twisted shielded wire.

[0034] After the device is powered on, the millivolt voltmeter 2 displays the shaft voltage value in real time, and the alarm threshold is preset to 340 mV through the potentiometer.

[0035] When the shaft voltage exceeds the threshold, the built-in single-tube voltage amplifier amplifies the signal to 5V to drive the relay to act, synchronously triggering the scene flash alarm lamp and sending a dry contact signal to the DCS system, forming a local and remote dual-channel alarm; when the shaft voltage falls below 300 mV, the relay is automatically reset.

[0036] During routine maintenance, the carbon brush powder needs to be cleaned regularly, the contact resistance needs to be detected to be lower than 0.1Ω, and the alarm system reliability needs to be verified by simulating the injection of 340 mV voltage every half year, so as to realize closed-loop monitoring and early warning of shaft voltage abnormalities.

[0037] As an optional embodiment, referring to Figures 1-5 , the embodiment provides a high-voltage motor G shaft voltage on-line measuring device, which comprises a mounting box 1, an accommodating cavity 11 is arranged on the inner wall of the mounting box 1, and a voltmeter 2 is arranged in the accommodating cavity 11; a receiving part 3 and a clamping part 4 are arranged in the accommodating cavity 11, and the voltmeter 2 is connected with a sampling electrode 5 through the receiving part 3; the mounting box 1 is connected with a motor G through the clamping part 4, and the clamping state of the clamping part 4 and the motor G can control the receiving and releasing state of the receiving part 3 to the connecting lead 52.

[0038] It should be noted that the accommodating cavity 11 can also accommodate the required devices such as a source amplifier and a potentiometer; the receiving part 3 can receive the connecting lead 52 connected with the sampling electrode 5 and the voltmeter 2, when the mounting box 1 is not connected with the motor G shell through the clamping part 4, the clamping part 4 limits the receiving part 3, so that the receiving part 3 cannot rotate, at this time, the connecting lead 52 cannot be elongated from the side wall of the mounting box 1, and the safety in use is improved; when the mounting box 1 is connected with the motor G shell through the clamping part 4, the clamping part 4 no longer limits the receiving part 3, at this time, the connecting lead 52 can be pulled out to be connected with the sampling electrode 5; it should also be noted that in the initial state, one end of the connecting lead 52 is connected with the voltmeter 2, and the other end is pulled out of the mounting box 1 through the receiving part 3 from the side wall of the mounting box 1.

[0039] Referring to Figure 3 , specifically, the receiving part 3 comprises a first receiving disc 31 and a second receiving disc 32, the inner walls of the first receiving disc 31 and the second receiving disc 32 are provided with clockwork springs, and the sampling electrode 5 is connected with the voltmeter 2 through the connecting lead 52 respectively penetrating through the first receiving disc 31 and the second receiving disc 32.

[0040] When it is necessary to measure the shaft voltage of the high-voltage motor G, the operator only needs to fix the installation box 1 on the motor G through the clamping piece 4, at this time the receiving piece 3 is in a relaxed state, and the connecting wire 52 can be freely pulled out of the receiving piece 3. After the connection is completed, the receiving piece 3 winds the connecting wire 52 under the action of the clock spring, avoids the disorder of the wire, and maintains the neatness of the measuring device. The principle is the same as the winding principle of the multifunctional charging line in the prior art. In the measurement process, the voltmeter 2 displays the shaft voltage value at both ends of the rotor of the motor G in real time, and the operator can adjust the potentiometer to set the alarm threshold value as needed. Once the shaft voltage exceeds the preset alarm threshold value, the alarm unit will trigger immediately to realize timely abnormal monitoring and early warning. In addition, the design of the installation box 1 makes the whole measuring device convenient to carry and install, improving the flexibility and convenience of measurement.

[0041] Further, the first receiving disc 31 is provided with a clamping rod 33 at the bottom end, and the clamping rod 33 is connected with the clamping piece 4 through the bottom end of the installation box 1. The clamping rod 33 is provided with two groups, which are the first rod 331 and the second rod 332.

[0042] Reference Figure 4 Further, the clamping piece 4 includes a first clamping plate 41 and a second clamping plate 42 connected with the first clamping plate 41 through a reset spring. The first rod 331 penetrates the bottom end of the installation box 1 and is connected with the first clamping plate 41, and the second rod 332 penetrates the moving slot of the bottom end of the installation box 1 and is connected with the second clamping plate 42. The second rod 332 can move along the moving slot to adapt to the size of the motor G.

[0043] It should be noted that the first receiving disc 31 and the second receiving disc 32 are fixedly connected with a limiting disc 34 at the end, and the side wall of the limiting disc 34 is fixedly connected with a limiting block 35. The end of the second rod 332 away from the second clamping plate 42 is fixedly connected with a limiting plate 43, and the side of the limiting plate 43 close to the limiting block 35 is provided with a limiting slot 44 matched with the limiting block 35. When setting the initial state, the first clamping plate 41 and the second clamping plate 42 are at the shortest distance, at this time the limiting plate 43 is close to the side wall of the limiting disc 34, and the limiting block 35 is located in the limiting slot 44, so that the receiving disc cannot rotate.

[0044] The first receiving disc 31 and the second receiving disc 32 are provided to prevent the connecting wire 52 from winding in the installation box 1. Since the end of the connecting wire 52 away from the voltmeter 2 always extends out of the installation box 1, if the receiving disc is not provided, most of the connecting wire 52 will extend out of the installation box 1 during the receiving and moving process. After the connecting wire 52 is received through the receiving box, the connecting wire 52 only has the connector extending out of the opening 12 of the installation box 1 in the non-use state, which increases the safety and service life of the connecting wire 52.

[0045] Referring to Figure 5 Further, the side wall of the mounting box 1 is provided with an opening 12, and the connecting wire 52 penetrates through the opening 12.

[0046] Further, the opening 12 comprises a first hole 121 and a second hole 122 connected with the first hole 121, the length of the first hole 121 is greater than that of the second hole 122, the second hole 122 is close to the inner wall of the mounting box 1, and the first hole 121 is close to the outer wall of the mounting box 1.

[0047] Still further, the opening 12 is provided with a blocking piece 6; when there is no external force to pull the connecting wire 52 towards the outer wall of the mounting box 1, the blocking piece 6 is used to block the movement of the connecting wire 52 along the opening 12.

[0048] Referring to Figure 5 The blocking piece 6 comprises a first baffle 61 and a second baffle 62, one end of the first baffle 61 is connected with the inner wall of the first hole 121 through a spring, one end of the second baffle 62 is connected with the inner wall of the second hole 122 through an extension rod, a first plate 63 is fixedly connected to the side of the first baffle 61 close to the second baffle 62, a second plate 64 is arranged on the side of the second baffle 62 close to the first plate 63, and in the initial state, the first plate 63 is in contact with the second plate 64, the first baffle 61 and the second baffle 62 simultaneously abut the connecting wire 52 against the inner wall of the opening 12, so that the friction of the connecting wire 52 when moving becomes larger.

[0049] In use, first, the sampling electrode 5 is connected with the end cover of the motor G through bolts through the insulating frame 51, then the second clamping plate 42 is pulled to make the distance between the second clamping plate 42 and the first clamping plate 41 larger, so that the first clamping plate 41 and the second clamping plate 42 can be clamped on the motor G shell at the same time, thereby fixing the whole mounting box 1.

[0050] When the second clamping plate 42 is pulled to make the distance between the second clamping plate 42 and the first clamping plate 41 larger, the limiting plate 43 at the end of the second clamping plate 42 is no longer in contact with the limiting disc 34, at this time the limiting block 35 is disengaged from the limiting groove 44, and the storage disc can rotate.

[0051] Next, the connecting wire 52 at the opening 12 is pulled to make the connecting wire 52 connected with the sampling electrode 5, in the process of pulling the connecting wire 52, the first baffle 61 moves in the direction close to the spring under the external pulling force, when the first baffle 61 moves in the direction close to the spring, the first plate 63 is no longer in abutment with the second plate 64, the second baffle 62 moves in the direction of the extension rod thereof under the force of the outward movement of the connecting wire 52, at this time the gap between the first baffle 61 and the opening 12 becomes larger, and the gap between the second baffle 62 and the opening 12 also becomes larger, so that the connecting wire 52 can move outward from the opening 12 smoothly.

[0052] When the connecting wire 52 is connected with the sampling electrode 5, the external force pulling the connecting wire 52 is lost, the first baffle 61 moves away from the spring under the action of the spring force, the first baffle 61 pushes the second baffle 62 to move away from the telescopic rod through the first plate 63 and the second plate 64 in the process of moving, until the first baffle 61 and the second baffle 62 simultaneously abut against the connecting wire 52, at this time, the friction of the connecting wire 52 moving along the opening 12 becomes larger, and the connecting wire 52 cannot easily move along the opening 12 without the external force pulling the connecting wire 52.

[0053] Referring to Figure 6 In an alternative embodiment, the blocking piece 6 further comprises a deformable blocking plug 65, one side of the blocking plug 65 is connected with the inner wall of the opening 12, when the external force pulls the connecting wire 52, the connecting wire 52 moves to the outer wall of the opening 12 and drives the end of the blocking plug 65 to simultaneously extend to the outer wall of the opening 12, at this time, the connecting wire 52 can smoothly move along the inner wall of the opening 12, when the connecting wire 52 is connected with the sampling electrode 5, the blocking plug 65 restores to abut against the connecting wire 52 under the memory attribute of the deformable material of the blocking plug 65, at this time, the friction of the connecting wire 52 moving along the opening 12 becomes larger, and the connecting wire 52 cannot easily move along the opening 12 without the external force pulling the connecting wire 52.

[0054] Finally, it should be noted that the above detailed description of the method and device is only an embodiment, and those skilled in the art can modify the embodiment in different ways without departing from the scope of the present application.

Claims

1. A method for online measurement of high-voltage motor shaft voltage, characterized by: include, A sampling electrode (5) and a voltmeter (2) connected to the sampling electrode (5) via a wire; Two groups of sampling electrodes (5) are provided, and the two groups of sampling electrodes (5) are respectively connected to the two ends of the shaft of the motor (G) to be measured, and the voltage difference of the electrode shaft can be obtained through the two groups of sampling electrodes (5); The voltmeter (2) is connected with a source amplifier, a potentiometer and a control switch to form a series circuit; The voltage meter (2) displays the shaft voltage value at both ends of the motor (G) rotor in real time, and then sets the alarm threshold of the potentiometer; When the voltage at both ends exceeds the preset alarm threshold, the alarm unit will be triggered to alarm.

2. The method for online measurement of high-voltage motor shaft voltage according to claim 1, characterized in that: The sampling electrode (5) is fixed to the end cover of the motor (G) via an insulating bracket and is used for directly contacting the rotor surface to obtain a shaft voltage signal.

3. The method for online measurement of high-voltage motor shaft voltage according to claim 2, characterized in that: The lead wire of the sampling electrode (5) is led out through the motor (G) body temperature measuring element junction box to form a closed measurement loop isolated from the motor (G) rotor.

4. A high-voltage motor shaft voltage online measurement device, characterized by: The method for online measurement of the shaft voltage of a high-voltage motor according to any one of claims 1 to 3 further includes: An installation box (1) has an inner wall provided with a receiving cavity (11), wherein the receiving cavity (11) is used for placing a voltmeter (2); A receiving part (3) and a clamping part (4) are provided in the accommodating cavity (11); a connecting wire (52) of the voltmeter (2) is connected to the sampling electrode (5) through the receiving part (3); The installation box (1) is connected to the motor (G) via the clamping member (4), and the retraction and extension state of the receiving member (3) with respect to the connecting wire (52) can be controlled by the clamping state of the clamping member (4) and the motor (G).

5. The high-voltage motor shaft voltage online measurement device according to claim 4, characterized in that: The storage member (3) comprises a first storage tray (31) and a second storage tray (32); the inner walls of the first storage tray (31) and the second storage tray (32) are both provided with springs; the sampling electrode (5) is connected to the voltmeter (2) via a connecting wire (52) passing through the first storage tray (31) and the second storage tray (32).

6. The high-voltage motor shaft voltage online measurement device according to claim 5, characterized in that: A clamping rod (33) is provided at the bottom end of the first receiving tray (31), and the clamping rod (33) passes through the bottom end of the installation box (1) and is connected to the clamping member (4); The clamping rods (33) are provided in two groups, namely a first rod (331) and a second rod (332).

7. The high-voltage motor shaft voltage online measurement device according to claim 6, characterized in that: The clamping member (4) comprises a first clamping plate (41) and a second clamping plate (42) connected thereto via a return spring; The first rod (331) passes through the bottom end of the installation box (1) and is connected to the first clamping plate (41), and the second rod (332) passes through the movable groove at the bottom end of the installation box (1) and is connected to the second clamping plate (42); The second rod (332) is movable along the movable slot to adapt to the size of the motor (G).

8. The high-voltage motor shaft voltage online measurement device according to claim 7, characterized in that: The side wall of the installation box (1) is provided with an opening (12), and the connecting wire (52) passes through the opening (12).

9. The high-voltage motor shaft voltage online measurement device according to claim 8, characterized in that: The opening (12) comprises a first hole (121) and a second hole (122) connected to the first hole (121); the length of the first hole (121) is greater than that of the second hole (122); the second hole (122) is close to the inner wall of the installation box (1); and the first hole (121) is close to the outer wall of the installation box (1).

10. The high-voltage motor shaft voltage online measurement device according to claim 9, characterized in that: A blocking member (6) is provided on the opening (12); When there is no external force pulling the connecting wire (52) toward the outer wall of the installation box (1), the blocking member (6) is used to block the connecting wire (52) from moving along the opening (12).

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