Automatic measuring device for rotor one-point grounding test

Abstract

An automatic measuring device used for a rotor one-point grounding test comprises a device body box, the device body box is provided with a power supply jack used for being connected with a power supply and a rotor grounding test interface used for being connected with a rotor, and an automatic adjusting resistance plate is arranged in the device body box. The automatic adjusting resistance plate is electrically connected with the power jack and the rotor grounding test interface, a test circuit is arranged on the automatic adjusting resistance plate, and the automatic adjusting resistance plate is connected with the rotor by connecting circuits with different resistance values on the test circuit and detects the current and resistance values of the rotor, so that whether one point of the rotor is grounded is judged. The device integrates the resistance plate capable of automatically adjusting the resistance value, a current measuring element, a resistance measuring element and a visual liquid crystal display screen, the overall integration degree of the device is high, the measuring process of a rotor one-point grounding experiment can be greatly simplified, and the resistance value of the resistance plate can be automatically adjusted without human intervention; and the final action resistance value and current can be directly read from the display screen, so that an experimenter does not need to be in close contact with the busbar for measurement, and the safety coefficient is higher.

Description

Technical Field

[0001] The utility model relates to the technical field of hydrogenerator detection, in particular to an automatic measuring device for rotor single-point grounding test. Background Technique

[0002] Rotor grounding fault is a common fault form of generators. The rotor voltage used for protection is taken from the full voltage of the excitation winding. After a single-point grounding of the rotor, it will not cause great harm to the safe operation of the generator. However, if a second-point grounding fault occurs again, it will seriously threaten the safety of the generator. When two points of the excitation winding are grounded, a large current flows through, burning the rotor body, causing the air-gap magnetic flux to lose balance, resulting in unit vibration, and locally magnetizing the generator. Therefore, before the generator is connected to the grid, a rotor single-point grounding experiment needs to be carried out to ensure the reliability of the grounding protection action of the generator rotor.

[0003] The existing rotor grounding experiment process has the following defects: 1. The experiment requires a lot of instruments and equipment and takes a long time to prepare; 2. The experimental wiring is complex and needs to be repeatedly confirmed; 3. The adjustment of the resistance box is not flexible and accurate enough; 4. When measuring, it is necessary for people to be in close contact with the rotor busbar, which has potential safety hazards; Summary of the Invention

[0004] The technical problem to be solved by the utility model is to provide an automatic measuring device for rotor single-point grounding test, which saves the time for completing the rotor grounding experiment and increases the safety of the test personnel.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0006] An automatic measuring device for rotor single-point grounding test includes a device body box. The device body box is provided with a power socket for connecting to a power source and a rotor grounding test interface for connecting to a rotor. An automatic adjusting resistor plate is arranged inside the device body box. The automatic adjusting resistor plate is electrically connected to the power socket and the rotor grounding test interface. A test circuit is arranged on the automatic adjusting resistor plate. By connecting circuits with different resistance values on the test circuit to the rotor and detecting its current and resistance value, it is judged whether there is a single-point grounding of the rotor.

[0007] The test circuit of the above automatic adjusting resistor plate includes a control part and a resistor connection part. A plurality of resistors R connected in series are arranged on the resistor connection part. Time relay switches are led out in parallel between every two resistors R and at the end of the last resistor R. One end of the parallel connection is grounded after being electrically connected to an ammeter. One end of the first resistor R in series that is not involved in the series connection is connected to the rotor grounding test interface. Both ends of an ohmmeter are electrically connected to the ground and the rotor grounding test interface respectively.

[0008] There are 5 parallel time relay switches and 5 resistors R as described above. The time relay switches are the normally open switches of relays KM1, KM2, KM3, KM4, and KM5.

[0009] The above control part includes a start button S1. The positive pole of the power supply is connected to the start button S1, and the other end of the start button S1 is respectively electrically connected to the parallel control branch one and control branch two. The other ends of control branch one and control branch two are connected in parallel to the negative pole of the power supply;

[0010] Control branch one includes an input interface and a control relay KM coil;

[0011] Control branch two includes the coils of relays KM1, KM2, KM3, KM4, and KM5 connected in series, the normally closed switch of control relay KM, and an indicator light.

[0012] The nodes of the above relays KM1, KM2, KM3, KM4, and KM5 have the function of delayed conduction and power-off holding, and their delays can be set to 5s, 10s, 15s, 20s, and 25s respectively; the resistance values of the 5 resistors R are all 200Ω.

[0013] The above ohmmeter and ammeter are electrically connected to the liquid crystal display screen, and the readings of the ammeter and ohmmeter can be displayed on the liquid crystal display screen.

[0014] An automatic measuring device for rotor single-point grounding test provided by the present utility model has the following beneficial effects:

[0015] In the rotor grounding experiment, this design can achieve:

[0016] (1) Improve the integration of the measuring device and save the process of preparing experimental tools;

[0017] (2) The device is easy to use and simple to operate; it automatically adjusts the resistance value and reduces human intervention

[0018] (3) The resistance adjustment accuracy is high, the measurement is more accurate, and the data reading is more direct;

[0019] (4) The measurement process can reduce the human close contact with the rotor busbar and improve the safety factor. Description of the Drawings

[0020] The present utility model will be further described below in conjunction with the drawings and embodiments:

[0021] Figure 1 is the structural schematic diagram of the device of the present utility model;

[0022] Figure 2 is the circuit schematic diagram of the automatic resistance adjusting plate.

[0023] In the figure: device body box 1, input interface 2, liquid crystal display screen 3, indicator light 4, grounding hole 5, rotor grounding test interface 6, automatic adjustment resistor board 7, power supply jack 8, grounding hole 9, resistor R, relays KM1, KM2, KM3, KM4 and KM5, control relay KM, start button S1. Specific implementation method

[0024] As Figure 1-2 As shown in the figure, an automatic measurement device for rotor single-point grounding test includes a device body box 1. A power supply jack 8 for connecting to a power supply and a rotor grounding test interface 6 for connecting to a rotor are provided on the device body box 1. An automatic adjustment resistor board 7 is provided inside the device body box 1. The automatic adjustment resistor board 7 is electrically connected to the power supply jack 8 and the rotor grounding test interface 6. A test circuit is provided on the automatic adjustment resistor board 7. By connecting circuits with different resistance values on the test circuit to the rotor and detecting its current and resistance value, it is judged whether there is single-point grounding on the rotor.

[0025] The test circuit of the above-mentioned automatic adjustment resistor board 7 includes a control part and a resistor connection part. A plurality of series-connected resistors R are provided on the resistor connection part. Time relay switches in parallel are led out between every two resistors R and at the end of the last resistor R. One end of the parallel connection is grounded after being electrically connected to an ammeter. One end of the first resistor R in series that is not involved in the series connection is connected to the rotor grounding test interface. Both ends of the ohmmeter are electrically connected to the ground and the rotor grounding test interface 6 respectively.

[0026] There are 5 time relay switches in parallel and resistors R as mentioned above. The time relay switches are normally open switches of relays KM1, KM2, KM3, KM4 and KM5.

[0027] The above-mentioned control part includes a start button S1. The positive pole of the power supply is connected to the start button S1. The other end of the start button S1 is respectively electrically connected to a parallel control branch one and a control branch two. The other ends of the control branch one and the control branch two are connected in parallel to the negative pole of the power supply;

[0028] Control branch one includes an input interface 2 and a control relay KM coil;

[0029] Control branch two includes a series connection of relays KM1, KM2, KM3, KM4 and KM5 coils, a control relay KM normally closed switch and an indicator light 4.

[0030] At the beginning stage of measurement, KM1-5 and the KM relay are all conducting, and the indicator light should also be on. This loop is conducting, so the control relay KM is designed as a normally closed node.

[0031] The nodes of the above-mentioned relays KM1, KM2, KM3, KM4, and KM5 have the function of delayed conduction and power-off holding, and their delays can be set to 5s, 10s, 15s, 20s, and 25s respectively; the resistance values of the 5 resistors R are all 200Ω.

[0032] The above-mentioned ohmmeter and ammeter are electrically connected to the liquid crystal display screen 3, and the readings of the ammeter and ohmmeter can be displayed on the liquid crystal display screen 3.

[0033] When using this device to conduct a rotor single-point grounding experiment, the operation steps are as follows:

[0034] 1. First, ground the device;

[0035] 2. Connect the power supply of the device;

[0036] 3. Connect the rotor single-point grounding test experiment wire and connect a group of trip input signals;

[0037] 4. Press the start button to start the measurement;

[0038] 5. The relays KM1, KM2, KM3, KM4, and KM5 are successively turned on, and the rotor single-point grounding resistance automatically starts to gradually decrease from the maximum value of 1kΩ by 200Ω. At this time, the indicator light is on. When a trip occurs, the incoming input signal causes the relay KM to act, causing its normally closed node to open and the indicator light to go out; the power-off node states of the relays KM1, KM2, KM3, KM4, and KM5 are maintained. Assume that after KM3 is turned on, the device receives an incoming input signal and the indicator light goes out, indicating that this experiment is completed. At this time, the normally open nodes of KM1, KM2, and KM3 are all closed, and the rotor single-point grounding resistance is 600Ω. The resistance value and current value can both be read on the display screen.

[0039] The principle of the present utility model:

[0040] The rotor grounding is not completely directly grounded. When a grounding fault occurs, there will be a resistance between the rotor and the ground. This resistance value is relatively small. When this value is less than the trip action setting value set in the rotor grounding protection device, the protection device issues a trip signal. The signal circuit node is led out and connected to the trip input signal node (i.e., the input interface 2) connected to the rotor single-point grounding experiment measuring device, causing the relay KM to conduct. The nodes 1 and 2 of KM conduct, and the indicator light 4 goes out, indicating that the rotor grounding resistance is less than the action setting value at this time, and this verification of the rotor single-point grounding experiment is correct.

Claims

1. An automatic measuring device for rotor single-point grounding test, characterized in that: The invention comprises a device body box (1), the device body box (1) is provided with a power socket (8) for connecting to a power source and a rotor grounding test interface (6) for connecting to a rotor, an automatic adjustment resistor board (7) is provided inside the device body box (1), the automatic adjustment resistor board (7) is electrically connected to the power socket (8) and the rotor grounding test interface (6), and a test circuit is provided on the automatic adjustment resistor board (7), and by connecting circuits with different resistance values ​​on the test circuit to the rotor and detecting the current and resistance value thereof, it is determined whether the rotor is grounded at one point.

2. The automatic measuring device for rotor single point grounding test according to claim 1 is characterized in that: The test circuit of the automatic regulating resistor board (7) comprises a control part and a resistor connection part, wherein a plurality of resistors R connected in series are arranged on the resistor connection part, and a time relay switch connected in parallel is led between every two resistors R and the last resistor R, and one end of the parallel connection is electrically connected to an ammeter and then grounded, and the end of the first resistor R in series that is not involved in the series connection is connected to a rotor grounding test interface, and the two ends of the ohmmeter are electrically connected to the ground and the rotor grounding test interface (6) respectively.

3. The automatic measuring device for rotor single point grounding test according to claim 2 is characterized in that: The parallel time relay switches and resistors R are both 5, and the time relay switches are relays KM1, KM2, KM3, KM4 and KM5 normally open switches.

4. The automatic measuring device for rotor single-point grounding test according to claim 3 is characterized in that: The control part includes a start button S1, the positive pole of the power supply is connected to the start button S1, the other end of the start button S1 is electrically connected to the parallel control branch 1 and the control branch 2, and the other ends of the control branch 1 and the control branch 2 are connected to the negative pole of the power supply; The control branch 1 includes an input interface (2) and a control relay KM coil; The control branch 2 includes the coils of relays KM1, KM2, KM3, KM4 and KM5 connected in series, the normally closed switch of the control relay KM and an indicator light (4).

5. The automatic measuring device for rotor single point grounding test according to claim 4 is characterized in that: The nodes of the relays KM1, KM2, KM3, KM4 and KM5 have the functions of delayed conduction and power-off retention, and the delay can be set to 5s, 10s, 15s, 20s, 25s respectively; the resistance values ​​of the five resistors R are all 200Ω.

6. The automatic measuring device for rotor single point grounding test according to claim 5, characterized in that: The ohmmeter and the ammeter are electrically connected to the liquid crystal display screen (3), and the readings of the ammeter and the ohmmeter can be displayed on the liquid crystal display screen (3).

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