Insulation testing device for passenger train

Abstract

The utility model discloses a passenger train insulation test device comprising a housing, and the tail part of the housing is provided with a connecting line socket. A change-over switch, an ampere meter and an indicator lamp panel are arranged on a panel at the front end of the shell The change-over switch is provided with a leakage current gear, a stop gear, a DC110V insulation gear and a DC48V insulation gear, the power supply end of the ampere meter is connected with the output end of the power supply module, one terminal of the test end is connected with the midpoint of the midpoint resistor, the other end of the test end is connected with a PE pin of the connecting line socket, and the indicator lamp board is connected with the insulation resistance value test circuit board; a power supply module, an insulation resistance test circuit board and a midpoint resistor are installed in the shell, the input end of the power supply module is connected with the connecting line socket through an anti-reverse-connection circuit, the positive and negative electrodes of the input end of the insulation resistance test circuit board are connected with the positive and negative electrodes of the output end of the connecting line socket through a bipolar switch S2, and the input end PE pole is connected with the PE pin of the connecting line socket; positive and negative electrodes of the midpoint resistor are connected with positive and negative electrodes of the output end of the connecting line socket through the bipolar switch S1.

Description

Technical Field

[0001] The utility model relates to the technical field of insulation testing, in particular to an insulation testing device for railway passenger cars, which is used to test the insulation resistance value and leakage current of DC48V and DC110V power supply lines during the maintenance of railway passenger cars. Background Art

[0002] The DC48V and DC110V power supplies on railway passenger cars mainly supply power to the control circuit and some on-vehicle equipment. If the insulation resistance value of the power supply line to the ground decreases or there is leakage, the control circuit may lose its function, resulting in malfunction or refusal of the equipment to operate, and even short circuit may cause a fire, endangering the safety of train operation. Both DC48V and DC110V on railway passenger cars are floating ground power supply systems. When the positive and negative lines have a decrease in the resistance value to the ground at two or more places or are grounded, faults such as short circuit, malfunction of relay protection, and automatic devices may occur, endangering the safety of passengers and train operation. At the same time, according to the regulations of the China Railway Corporation, railway passenger car maintenance units need to use insulation testers to test the insulation of DC48V and DC110V of the vehicles. Currently, when railway passenger car maintenance units check for leakage faults, they still use test lamps for detection, which can only qualitatively judge the leakage phenomenon and cannot detect the leakage current value or determine whether the leakage value exceeds the standard.

[0003] The traditional method is to use a test lamp to check for leakage in the power supply line, and qualitatively judge the leakage by the redness degree of the test lamp, and it is impossible to accurately understand the degree of leakage. At the same time, when the leakage current is small, the test lamp does not turn red, and it is impossible to further process weak leakage faults. Among the existing insulation testing devices for railway passenger cars, for example, the Chinese invention patent with the application number CN201811080636.6 discloses a DC110V on-line insulation monitoring system and method, which includes a train-level insulation monitoring device, a vehicle-level insulation monitoring device, a midpoint resistance device, and a communication network; the train-level insulation monitoring device consists of a DC110V leakage alarm, a bus voltage sensor at the head and tail cars, and a ground voltage sensor; the vehicle-level insulation monitoring device consists of a leakage current sensor and a TLMK conditioning module; the midpoint resistance device includes a DC110V line-to-line resistance and a ground resistance. The train-level uses the voltage detection method to monitor the insulation of the whole train's DC110V system to the ground; the vehicle-level uses the current detection method to monitor the insulation of the DC110V system of this vehicle to the ground; the train-level and the vehicle-level cooperate with the midpoint resistance to work. However, this monitoring system still has the following defects: 1. This monitoring system can only monitor the 110V power supply line and cannot monitor the 48V power supply line, so the scope of use is limited; 2. This monitoring system is a real-time monitoring system installed on the vehicle and cannot be used as a maintenance tooling to test the insulation of the passenger car electrical system. Summary of the Invention

[0004] The technical problem to be solved by the utility model is to overcome the deficiencies of the prior art and provide an insulation testing device for railway passenger cars.

[0005] The utility model is realized through the following technical solutions:

[0006] An insulation testing device for railway passenger cars, comprising:

[0007] A housing 1, with a connection line socket 11 provided at the tail of the housing 1;

[0008] A change-over switch 2, arranged on the front panel of the housing 1, having four gears of leakage current, stop, DC110V insulation, and DC48V insulation, for selecting corresponding test functions and controlling the connection of the insulation resistance testing circuit board 6 and the midpoint resistor 8;

[0009] An anti-reverse connection circuit 3, with its input end connected to the connection line socket 11 and its output end connected to the input end of the power supply module 4, for preventing the circuit from being damaged due to reverse connection of the positive and negative poles;

[0010] A power supply module 4, installed inside the housing 1, with its input end connected to the output end of the anti-reverse connection circuit 3, for converting the input DC48V and DC110V into ±5V and +10V outputs;

[0011] An ammeter 5, arranged on the front panel of the housing 1, with its power supply end connected to the output end of the power supply module 4, one terminal of the test end connected to the midpoint of the midpoint resistor 8, and the other end connected to the PE pin of the connection line socket 11, for displaying the value of the leakage current;

[0012] An insulation resistance testing circuit board 6, installed inside the housing 1, with the positive and negative poles of the input end connected to the positive and negative lines of the output end of the connection line socket 11 through a bipolar switch S2, and the PE pole of the input end directly connected to the PE pin of the connection line socket 11, for detecting whether the insulation resistance of the line to the ground is normal;

[0013] An indicator light board 7, arranged on the front panel of the housing 1, connected to the insulation resistance testing circuit board 6, for displaying the test result of the insulation resistance to the ground and flashing for alarm;

[0014] A midpoint resistor 8, with its positive and negative poles connected to the output end of the connection line socket 11 through a bipolar switch S1, installed inside the housing 1, for testing the leakage current of the line.

[0015] 2. The insulation resistance testing circuit board 6 described above includes:

[0016] A control unit U1;

[0017] A relay K1, which is a bipolar relay, with the two contacts at the input end respectively connected to the power supply positive pole and the PE end. The coil of the relay K1 is connected in parallel with a zener diode D2. One end of the coil of the relay K1 is connected in parallel with the positive pole of the zener diode D2 to the ground, and the other end of the coil of the relay K1 is connected in parallel with the negative pole of the zener diode D2 to the +10V power supply;

[0018] The bridge-type detection circuit 61 has its input end connected to the output end of the relay K1, and the bridge-type detection circuit 61 is connected to the control unit U1 through the solid-state relays U4, U5, and U6;

[0019] The alarm circuit 62 is electrically connected to the control unit U1.

[0020] Further, the bridge-type detection circuit 61 is connected to the positive power supply contact at the output end of the relay K1 and then divides into two paths to connect the resistor R14 and the positive-to-ground reference resistor R3 respectively; the other end of the positive-to-ground reference resistor R3 is connected to the secondary side pin 3 of the solid-state relay U4, and the other end of the resistor R14 is connected to the primary side input end of the linear optocoupler U2. The primary side output end of the linear optocoupler U2 is connected to the resistor R25; the other end of the resistor R25 divides into two paths to connect the primary side input end of the linear optocoupler U3 and the positive pole of the diode D4 respectively. The primary side output end of the linear optocoupler U3 is connected to the resistor R17 and then to the negative power supply; the negative pole of the diode D4 divides into two paths to connect the positive pole of the diode D3 and the resistor R23, and the negative pole of the diode D3 is connected to the primary side output end of the linear optocoupler U2; the other end of the resistor R23 divides into three paths to be connected in parallel to the secondary side pin 4 of the solid-state relays U4 and U5 and the secondary side pin 3 of the solid-state relay U6. The secondary side pin 3 of the solid-state relay U5 is connected to the PE pole contact at the output end of the relay K1, and the secondary side pin 4 of the solid-state relay U6 is connected to the negative-to-ground reference resistor R4 and then to the negative power supply;

[0021] The secondary side input end of the linear optocoupler U2 is connected in parallel to the 13th pin of the control unit U1 and the resistor R22, the secondary side input end of the linear optocoupler U3 is connected in parallel to the 12th pin of the control unit U1 and the resistor R24, the secondary side output ends of the linear optocouplers U2 and U3 are connected in parallel to the 10th pin of the control unit U1, and the other ends of the resistors R22 and R24 are connected to the +5V power supply;

[0022] The secondary side pin 1 of the solid-state relays U4, U5, and U6 are respectively connected to R5, R13, and R6 and then connected in parallel to the 20th pin of the control unit U1. The 20th pin of the control unit U1 is also connected to the +5V power supply; the secondary side pin 2 of the solid-state relays U4, U5, and U6 are respectively connected to the 15th pin, 16th pin, and 14th pin of the control unit U1.

[0023] Further, both the positive-to-ground reference resistor R3 and the negative-to-ground reference resistor R4 are composed of two resistors with a resistance value of 2KΩ connected in parallel, and one branch of the positive-to-ground reference resistor R3 and one branch of the negative-to-ground reference resistor R4 are controlled and connected through a bipolar switch S3.

[0024] Further, when the conversion switch 2 selects the "leakage current" gear, the bipolar switch S1 is turned on, and the bipolar switches S2 and S3 are turned off; when the conversion switch 2 selects the "stop" gear, the bipolar switches S1, S2, and S3 are all turned off; when the conversion switch 2 selects the "DC110V insulation" gear, the bipolar switch S2 is turned on, and the bipolar switches S1 and S3 are turned off; when the conversion switch 2 selects the "DC48V insulation" gear, the bipolar switches S2 and S3 are turned on, and the bipolar switch S1 is turned off.

[0025] Further, five indicator lights, namely a power supply light LED1, a positive line normal light LED2, a positive line alarm light LED3, a negative line normal light LED4, and a negative line alarm light LED5, are provided on the indicator light board 7. The 20th pin of the control unit U1 is connected in parallel with the positive electrode of the power supply light LED1, the resistor R8, and the resistor R10. The negative electrode of the LED1 is connected to R7. The other end of the resistor R8 is successively connected in series with the positive electrode of the positive line normal light LED2, the positive electrode of the positive line alarm light LED3, and the resistor R9. The other end of the resistor R10 is successively connected in series with the positive electrode of the negative line normal light LED4, the positive electrode of the negative line alarm light LED5, and the resistor R11; the other ends of the resistors R7, R9, and R11 are grounded;

[0026] The 1st pin of the control unit U1 is connected to the resistor R18 and then connected in parallel with the 10th pin of the control unit U1 to be grounded.

[0027] Further, the alarm circuit 62 includes a buzzer 621. The positive electrode of the buzzer 621 is connected to the +10V power supply, and the negative electrode is connected to the 1st pin of the triode T1; the 2nd pin of the triode T1 is branched into two paths and is respectively connected to the 10th pin and the 11th pin of the control unit U1 through the resistor R20 and the resistor R26. The 3rd pin of the triode T1 is connected to the 10th pin of the control unit U1; a diode D8 and a resistor R19 are connected in parallel on the 11th pin of the control unit U1, and the other ends of the diode D8 and the resistor R19 are connected in parallel to the +5V power supply.

[0028] Further, the reverse connection prevention circuit 3 is composed of four diodes to form a bridge structure.

[0029] Further, the midpoint resistor 8 includes two inter-line resistors R101, R102 and a ground resistor RE. The two inter-line resistors R101, R102 are connected in series, and both ends are respectively connected to the positive and negative power supply lines; one end of the ground resistor RE is connected to the wire between the two inter-line resistors R101, R102, and the other end is connected to the ground wire in series with the ammeter 5.

[0030] Further, an aluminum heat sink 81 is installed below or above the midpoint resistor 8.

[0031] The working principle of the present utility model:

[0032] When the device is in use, the operator connects the quick plug of the test line 12 to the connection socket 11 on the rear panel of the detector housing 1. Then, use alligator clips to connect the positive and negative wires and the PE wire of the power supply system to be tested. The red alligator clip is connected to the positive power wire, the black alligator clip is connected to the negative power wire, and the yellow alligator clip is connected to the PE wire. Ensure that the tester conversion switch 2 is in the "Stop" position before connection and ensure no-power operation during connection. When conducting a power-on test, if testing the insulation of the DC110V positive and negative busbars to the ground, turn the conversion switch 2 to the "DC110V Insulation" position; if testing the insulation of the DC48V positive and negative busbars to the ground, turn the conversion switch 2 to the "DC48V Insulation" position; if testing the leakage current, turn the conversion switch 2 to the "Leakage Current" position.

[0033] During the insulation test, if the insulation resistance value of the positive wire to the ground is less than the alarm value, the two indicator lights, the positive wire normal light LED2 and the positive wire alarm light LED3, will flash alternately; if the insulation resistance value of the negative wire to the ground is less than the alarm value, the two indicator lights, the negative wire normal light LED4 and the negative wire alarm light LED5, will flash alternately. The alarm value for DC48V insulation detection is 1k; the alarm value for DC110V insulation detection is 2k.

[0034] Principle of testing the insulation resistance value to the ground: Detect the insulation resistance value through the bridge method. When the current through the positive-to-ground insulation resistance Rx is greater than the positive-to-ground reference resistance R3, the positive wire alarms; when the current through the positive-to-ground insulation resistance Ry is greater than the negative-to-ground reference resistance R4, the negative wire alarms. By changing the resistance values of the positive-to-ground reference resistance R3 and the negative-to-ground reference resistance R4, the testing of the insulation resistance value to the ground for the DC48V and DC110V power supply lines can be made compatible. When detecting DC110V, the positive-to-ground reference resistance R3 and the negative-to-ground reference resistance R4 are 2K respectively; when detecting DC48V, the positive-to-ground reference resistance R3 and the negative-to-ground reference resistance R4 are 1K respectively.

[0035] During the DC48V leakage current test, when the leakage current of a single vehicle exceeds 10mA, the alarm circuit 62 will alarm; during the DC110V leakage current test, when the leakage current of a single vehicle exceeds 30mA, the alarm circuit 62 will alarm.

[0036] Principle of testing the leakage current: Detect the leakage current by using the method of the midpoint resistance 8. When there is leakage, the leakage current flows back to the power supply through the resistance RE to the ground. Therefore, by connecting an ammeter in series between the ground and RE, the leakage current can be measured.

[0037] Advantages of the present utility model compared with the prior art:

[0038] The present utility model realizes the accurate detection of the leakage current value, can detect whether the insulation resistance value of the line to the ground meets the requirements of the regulations, and is accompanied by audible and visual alarms, increasing its convenience.

[0039] When the utility model is in use, only need to connect this tester into the circuit to be tested, and select the corresponding test function through the change-over switch, with simple and convenient operation; the method is simple and the detection efficiency is high.

[0040] The utility model can realize the test of the ground insulation resistance value and the leakage current test of the power supply lines compatible with DC48V and DC110V, with wide applicability.

[0041] The utility model is small in volume, and the staff can carry the tester to move to different vehicles for detection, with convenient carrying and operation. Description of the Drawings

[0042] Figure 1 is a three-dimensional structural schematic diagram of the utility model;

[0043] Figure 2 is a front view of the utility model;

[0044] Figure 3 is an internal structural schematic diagram of the utility model;

[0045] Figure 4 is a circuit diagram of the utility model;

[0046] Figure 5 is a circuit diagram of the insulation resistance value test circuit board and the indicator lamp board of the utility model;

[0047] Figure 6 is a circuit schematic diagram of the bridge-type detection circuit of the utility model.

[0048] Reference numerals in the drawings:

[0049] 1 - housing, 11 - connecting wire socket, 12 - test wire;

[0050] 2 - change-over switch; 3 - reverse connection prevention circuit; 4 - power supply module; 5 - ammeter;

[0051] 6 - insulation resistance value test circuit board, 61 - bridge-type detection circuit, 62 - alarm circuit, 621 - buzzer;

[0052] 7 - indicator lamp board; 8 - midpoint resistor, 81 - aluminum heat sink. Detailed Embodiments

[0053] In order to enable those skilled in the art of this technical field to better understand the technical solution of the utility model, the following will make a detailed description of its specific embodiments in conjunction with the drawings.

[0054] As Figures 1-6As shown in the figure, the railway passenger car insulation test device includes a housing 1, and a connection line socket 11 is provided at the tail of the housing 1; a changeover switch 2, an ammeter 5 and an indicator board 7 are provided on the front panel of the housing 1; the changeover switch 2 is provided with four gears: leakage current, stop, DC110V insulation, and DC48V insulation. The power supply end of the ammeter 5 is connected to the output end of the power supply module 4. One terminal of the test end is connected to the midpoint of the midpoint resistor 8, and the other end is connected to the PE pin of the connection line socket 11; the indicator board 7 is connected to the insulation resistance test circuit board 6; a power supply module 4, an insulation resistance test circuit board 6 and a midpoint resistor 8 are installed inside the housing 1. The input end of the power supply module 4 is connected to the connection line socket 11 through an anti-reverse connection circuit 3. The positive and negative poles of the input end of the insulation resistance test circuit board 6 are connected to the positive and negative poles of the output end of the connection line socket through a bipolar switch S2, and the PE pole of the input end is connected to the PE pin of the connection line socket 11; the positive and negative poles of the midpoint resistor 8 are connected to the positive and negative poles of the output end of the connection line socket through a bipolar switch S1.

[0055] In the embodiment, as Figure 5 shown, the insulation resistance test circuit board 6 includes a control unit U1, a relay K1, a bridge detection circuit 61 and an alarm circuit 62; the relay K1 is a bipolar relay, and the two contacts at the input end are respectively connected to the positive power supply and the PE end. The coil of the relay K1 is connected in parallel with the zener diode D2. One end of the coil of the relay K1 is connected in parallel to the ground through the positive pole of the zener diode D2, and the other end of the coil of the relay K1 is connected in parallel to the +10V power supply through the negative pole of the zener diode D2; the input end of the bridge detection circuit 61 is connected to the output end of the relay K1, and the bridge detection circuit 61 is connected to the control unit U1 through solid state relays U4, U5, U6; the alarm circuit 62 is electrically connected to the control unit U1.

[0056] In the embodiment, as Figures 4-6 shown, the bridge detection circuit 61 is connected to the positive power supply contact at the output end of the relay K1 and then branches into two paths to be respectively connected to the resistor R14 and the positive-to-ground reference resistor R3; the other end of the positive-to-ground reference resistor R3 is connected to the secondary side 3 pin of the solid state relay U4, and the other end of the resistor R14 is connected to the primary side input end of the linear optocoupler U2. The primary side output end of the linear optocoupler U2 is connected to the resistor R25; the other end of the resistor R25 branches into two paths to be respectively connected to the primary side input end of the linear optocoupler U3 and the positive pole of the diode D4. The primary side output end of the linear optocoupler U3 is connected to the resistor R17 and then connected to the negative power supply; the negative pole of the diode D4 branches into two paths to be connected to the positive pole of the diode D3 and the resistor R23. The negative pole of the diode D3 is connected to the primary side output end of the linear optocoupler U2; the other end of the resistor R23 branches into three paths and is connected in parallel to the secondary side 4 pins of the solid state relays U4, U5 and the secondary side 3 pin of the solid state relay U6. The secondary side 3 pin of the solid state relay U5 is connected to the PE pole contact at the output end of the relay K1. The secondary side 4 pin of the solid state relay U6 is connected to the negative-to-ground reference resistor R4 and then connected to the negative power supply;

[0057] The secondary input terminals of linear optocoupler U2 are connected in parallel to pin 13 of control unit U1 and resistor R22. The secondary input terminals of linear optocoupler U3 are connected in parallel to pin 12 of control unit U1 and resistor R24. The secondary output terminals of linear optocouplers U2 and U3 are connected in parallel to pin 10 of control unit U1. The other ends of resistors R22 and R24 are connected to the +5V power supply.

[0058] The secondary pin 1 of solid-state relays U4, U5, and U6 are respectively connected to R5, R13, and R6 and then connected in parallel to pin 20 of control unit U1. Pin 20 of control unit U1 is also connected to the +5V power supply. The secondary pin 2 of solid-state relays U4, U5, and U6 are respectively connected to pins 15, 16, and 14 of control unit U1.

[0059] In the embodiment, as Figure 4 shown, the positive-to-ground reference resistor R3 and the negative-to-ground reference resistor R4 are both composed of two 2KΩ resistors connected in parallel. One branch of the positive-to-ground reference resistor R3 and one branch of the negative-to-ground reference resistor R4 are controlled and connected through a bipolar switch S3.

[0060] In the embodiment, when the changeover switch 2 selects the "leakage current" gear, the bipolar switch S1 is turned on, and the bipolar switches S2 and S3 are turned off. The power positive and power negative pins of the four-core quick socket are connected to both ends of the midpoint resistor. When the changeover switch 2 selects the "stop" gear, the bipolar switches S1, S2, and S3 are all turned off, and there is no circuit conduction. When the changeover switch 2 selects the "DC110V insulation" gear, the bipolar switch S2 is turned on, and the bipolar switches S1 and S3 are turned off. The power positive and power negative pins of the four-core quick socket are connected to the positive and negative poles of the insulation resistance test board. When selecting the "DC48V insulation" gear, the bipolar switches S2 and S3 are turned on, and the bipolar switch S1 is turned off. The power positive and power negative pins of the four-core quick socket are connected to the positive and negative poles of the insulation resistance test board, and at the same time, two 2k resistors are respectively connected in parallel to the positive-to-ground reference resistor R3 and the negative-to-ground reference resistor R4.

[0061] In the embodiment, as Figure 5 shown, there are five indicator lights on the indicator light board 7, namely the power supply light LED1, the positive line normal light LED2, the positive line alarm light LED3, the negative line normal light LED4, and the negative line alarm light LED5. Pin 20 of control unit U1 is connected in parallel to the positive pole of the power supply light LED1, resistor R8, and resistor R10. The negative pole of LED1 is connected to R7. The other end of resistor R8 is successively connected in series to the positive pole of the positive line normal light LED2, the positive pole of the positive line alarm light LED3, and resistor R9. The other end of resistor R10 is successively connected in series to the positive pole of the negative line normal light LED4, the positive pole of the negative line alarm light LED5, and resistor R11. The other ends of resistors R7, R9, and R11 are grounded. Pin 1 of control unit U1 is connected to resistor R18 and then connected in parallel to ground with pin 10 of control unit U1.

[0062] In an embodiment, as Figure 5 shown, the alarm circuit 62 includes a buzzer 621. The positive electrode of the buzzer 621 is connected to the +10V power supply, and the negative electrode is connected to the 1st pin of the triode T1. The 2nd pin of the triode T1 is branched into two paths, and is respectively connected to the 10th pin and the 11th pin of the control unit U1 through a resistor R20 and a resistor R26. The 3rd pin of the triode T1 is connected to the 10th pin of the control unit U1. A diode D8 and a resistor R19 are connected in parallel on the 11th pin of the control unit U1, and the other ends of the diode D8 and the resistor R19 are connected in parallel to the +5V power supply.

[0063] In an embodiment, as Figure 4 shown, the reverse connection prevention circuit 3 is composed of four diodes to form a bridge structure to prevent the circuit from being damaged when reverse connected.

[0064] In an embodiment, as Figure 4 shown, the midpoint resistor 8 includes two inter-wire resistors R101, R102 and a ground resistor RE. The two inter-wire resistors R101, R102 are connected in series, and both ends are respectively connected to the positive and negative power lines. One end of the ground resistor RE is connected to the wire between the two inter-wire resistors R101, R102, and the other end is connected to the ground wire in series with the ammeter 5.

[0065] The midpoint resistor 8 is used to test the leakage current of the line. The inter-wire resistors R101, R102 are both composed of two 800Ω and two 200Ω power resistors connected in series. The ground resistor RE is composed of a 300Ω and a 200Ω power resistor connected in series. The power of each resistor is 25W. To ensure heat dissipation, an aluminum heat sink 81 is installed below or above the midpoint resistor 8.

[0066] In an embodiment, as Figures 4-6 shown, the insulation resistance test board obtains "+5V" and "+10V" power supplies from the power module, and the relay K1 is closed to connect "Power Positive" and "PE".

[0067] When testing the insulation resistance Rx between the positive terminal and the ground, the 15th pin of the control unit U1 is set to a low level, and the 14th and 16th pins are set to a high level. At this time, the primary side 1, 2 pins of the solid-state relay U4 are powered on, so that the secondary side 3, 4 pins are turned on, and the positive-to-ground reference resistor R3 is connected into the bridge. The current comes out from "Power Positive", one path goes through the positive-to-ground reference resistor R3, the solid-state relay U4, the resistor R23, the diode D3, the resistor R25, the primary side of the linear optocoupler U3, and the resistor R17 and returns to "Power Negative". Another path goes through R14, the primary side of the linear optocoupler U2, the resistor R25, the primary side of the linear optocoupler U3, and the resistor R17 and returns to "Power Negative". At this time, the current I U31 =I R3 +I R14 through the primary side of the linear optocoupler U3, and the current I U32 =μI U31, μ is a fixed constant, and the voltage at the connection point A between R24 and the linear optocoupler U3 is U A = 5V - I U32 × R 24 , and the 12th pin of the control unit U1 is for the AD converter to read the voltage value at point A.

[0068] Then, the 16th pin of the control unit U1 is set to low level, and the 14th and 15th pins are set to high level. At this time, the primary side 1 and 2 pins of the solid-state relay U5 are powered on, causing the secondary side 3 and 4 pins to conduct, and connecting the positive-to-ground insulation resistance Rx into the bridge. The current comes out from "positive power supply", one path goes through Rx, solid-state relay U4, resistor R23, diode D3, resistor R25, the primary side of linear optocoupler U3, and resistor R17 back to "negative power supply". Another path goes through resistor R14, the primary side of linear optocoupler U2, resistor R25, the primary side of linear optocoupler U3, and resistor R17 back to "negative power supply".

[0069] At this time, the current I' through the primary side of the linear optocoupler U3 U31 = I Rx + I R14 , and the current I' on the secondary side of the linear optocoupler U3 U32 = μI' U31 , μ is a fixed constant, and the voltage at the connection point A between R24 and the linear optocoupler U3 is U' A = 5V - I' U32 × R 24 . If U' A < U A , then I' U32 > I U32 , I Rx > I R3 , then R x < R 3 . Similarly, if U' A > U A , then R x > R 3 .

[0070] Similarly, when testing the negative-to-ground insulation resistance Ry, the 14th pin of the control unit U1 is set to low level, and the 15th and 16th pins are set to high level. At this time, the primary side 1 and 2 pins of the solid-state relay U6 are powered on, causing the secondary side 3 and 4 pins to conduct, and connecting the negative-to-ground reference resistance R4 into the bridge. The current comes out from "positive power supply", goes through R14, the primary side of linear optocoupler U2, and R25 and then divides into two paths. One path goes through D4, R23, and the negative-to-ground reference resistance R4 back to "negative power supply", and the other path goes through the primary side of linear optocoupler U3 and R17 back to "negative power supply".

[0071] At this time, the current I through the primary side of the linear optocoupler U2 U21 = I R4 + I R17, the current I on the secondary side of the linear optocoupler U2 U22 = μI U21 , where μ is a fixed constant, and the voltage at the connection point B between R22 and the linear optocoupler U2 is U B = 5V - I U22 × R 22 .

[0072] Similarly, after setting the 16th pin of the control unit U1 to low level and the 14th and 15th pins to high level, the negative-to-ground insulation resistance Ry is connected to the bridge. At this time, the current I' passing through the primary side of the linear optocoupler U2 U21 = I Ry + I R17 , and the current I' on the secondary side of the linear optocoupler U2 U22 = μI' U21 , and the voltage at the connection point B between R22 and the linear optocoupler U2 is U' B = 5V - I' U22 × R 24 . If U' B < U B , then I' U22 > I U22 , I Ry > I R4 , then R y < R 4 . Similarly, if U' B > U B , then R y > R 4 .

[0073] If the control unit U1 detects that U' A < U A or U' B < U B , that is, R x < R 3 or R y < R 4 , the 11th pin of the control unit U1 is set to high level, the triode T1 conducts, and the buzzer 621 emits a "beep beep beep" sound.

[0074] If the control unit U1 detects that U' A < U A , the 19th pin of the control unit U1 will generate alternating high and low levels, causing the LEDs LED2 and LED3 to flash alternately.

[0075] If the control unit U1 detects that U' B < U B , the 18th pin of the control unit U1 will generate alternating high and low levels, causing the LEDs LED4 and LED5 to flash alternately.

[0076] In an embodiment, the power supply module 4 is a wide-voltage power conversion module, and its model is the HDY-3 power supply module; the power supply module 4 mainly provides power for the ammeter 5, with an input voltage of 36 - 138V and outputs ±5V and +10V. The “+” and “-” at the input end of the power supply module 4 are respectively connected to the “+” and “-” at the output end of the reverse connection prevention circuit 3, and the “ground” and “+5V” at the output end are connected to the power supply terminals of the ammeter 5. The “ground”, “+5V” and “+10V” at the output end are connected to the “ground”, “+5”, “+10” terminals of the insulation resistance test board 6.

[0077] The control unit U1 is a PLC controller or a single-chip microcomputer.

[0078] The ammeter 5 is installed on the tester panel, with a range of ±500mA and a power supply of 5V. It is used to display the value of the leakage current. When the positive line leaks electricity, the displayed value is positive; when the negative line leaks electricity, the displayed value is negative. The ground and +5V of the ammeter 5 are connected to the ground and +5V at the output end of the power supply module 4. One of the test lines of the ammeter 5 is connected to the midpoint of the midpoint resistor 8, and the other is connected to the PE pin of the connection socket 11.

[0079] The working mode of the present utility model:

[0080] Step 1: The staff connects the quick plug of the test line 12 to the connection socket 11 on the rear panel of the detector.

[0081] Step 2: Use the alligator clips of the test line 12 to connect the positive and negative lines and the PE line of the power supply system to be tested. The red alligator clip is connected to the positive power line, the black alligator clip is connected to the negative power line, and the yellow alligator clip is connected to the PE line. Ensure that the tester change switch is in the “stop” position before connection, and ensure no-power operation during connection.

[0082] Step 3: Conduct a power-on test. If testing the insulation of the DC110V positive and negative busbars to the ground, turn the change switch to the “DC110V insulation” position; if testing the insulation of the DC48V positive and negative busbars to the ground, turn the change switch to the “DC48V insulation” position; if testing the leakage current, turn the change switch to the “leakage current” position.

[0083] Step 4: During insulation testing, if the insulation resistance value of the positive line to the ground is less than the alarm value, the two indicator lights “positive line normal” and “positive line alarm” will flash alternately. The same is true when the negative line alarms. The alarm value for DC48V insulation detection is 1k; the alarm value for DC110V insulation detection is 2k.

[0084] When testing the DC48V leakage current, if the leakage current of a single vehicle exceeds 10mA, the alarm circuit 62 will alarm;

[0085] When testing the DC110V leakage current, if the leakage current of a single vehicle exceeds 30mA, the alarm circuit 62 will alarm.

[0086] It should be noted that the technical solution of the present utility model has been introduced in detail above, and the principle of the present utility model has been described. The description of the above working principle is only used to help understand the core idea of the present utility model. It should be pointed out that for those of ordinary skill in the art of this technology, without departing from the principle of the present utility model, the present utility model can also be improved and modified, and these improvements and modifications also fall within the protection scope of the claims of the present utility model.

[0087] Those skilled in the art of the present utility model can make modifications or supplements to the described specific embodiments or use similar ways to replace them, as long as they do not deviate from the structure of the present utility model or exceed the scope defined by the claims, they all belong to the protection scope of the present utility model. Therefore, the protection scope of the patent of the present utility model shall be subject to the appended claims.

Claims

1. A railway passenger car insulation test device, characterized in that: include: A housing (1), wherein a connection line socket (11) is provided at the rear of the housing (1); The conversion switch (2) is arranged on a panel at the front end of the housing (1) and has four gears: leakage current, stop, DC110V insulation, and DC48V insulation, and is used to select a corresponding test function and control the connection between the insulation resistance test circuit board (6) and the midpoint resistor (8); The anti-reverse connection circuit (3) has an input end connected to the connection line socket (11) and an output end connected to the input end of the power module (4), and is used to prevent the positive and negative poles from being reversely connected and burning the circuit; A power module (4) is installed inside the housing (1), the input end of which is connected to the output end of the anti-reverse connection circuit (3), and is used to convert the input DC48V and DC110V into ±5V and +10V outputs; An ammeter (5) is arranged on a panel at the front end of the housing (1), a power supply end is connected to the output end of the power module (4), one terminal of the test end is connected to the midpoint of the midpoint resistor (8), and the other end is connected to the PE pin of the connection line socket (11), and is used to display the value of the leakage current; An insulation resistance test circuit board (6) is installed inside the housing (1), the positive and negative poles of the input end are connected to the positive and negative lines of the output end of the connection line socket (11) through a bipolar switch S2, and the PE pole of the input end is directly connected to the PE pin of the connection line socket (11), and is used to detect whether the insulation resistance of the line to the ground is normal; An indicator light board (7), arranged on a panel at the front end of the housing (1), connected to the insulation resistance test circuit board (6), and used for displaying the insulation resistance test result to the ground and flashing to give an alarm; The midpoint resistor (8), whose positive and negative poles are connected to the output end of the connection line socket (11) through a bipolar switch S1, is installed inside the housing (1) and is used to test the line leakage current.

2. The railway passenger car insulation test device according to claim 1, characterized in that: The insulation resistance test circuit board (6) comprises: Control unit U1; Relay K1 is a bipolar relay. The two contacts at the input end are connected to the positive pole of the power supply and the PE end respectively. The coil of relay K1 is connected in parallel with the voltage-stabilizing diode D2. One end of the coil of relay K1 is connected in parallel with the positive pole of the voltage-stabilizing diode D2 and grounded. The other end of the coil of relay K1 is connected in parallel with the negative pole of the voltage-stabilizing diode D2 and the +10V power supply. A bridge detection circuit (61), the input end of which is connected to the output end of the relay K1, and the bridge detection circuit (61) is connected to the control unit U1 via solid-state relays U4, U5, and U6; The alarm circuit (62) is electrically connected to the control unit U1.

3. The railway passenger car insulation test device according to claim 2, characterized in that: The bridge detection circuit (61) is connected to the positive power contact of the output end of the relay K1 and then divided into two paths to respectively connect the resistor R14 and the reference resistor R3 facing the ground; The other end of the positive reference resistor R3 to ground is connected to the 3rd pin of the secondary side of the solid-state relay U4, the other end of the resistor R14 is connected to the primary input end of the linear optocoupler U2, and the primary output end of the linear optocoupler U2 is connected to the resistor R25; the other end of the resistor R25 is divided into two paths, which are respectively connected to the primary input end of the linear optocoupler U3 and the positive electrode of the diode D4, and the primary output end of the linear optocoupler U3 is connected to the resistor R17 and then to the negative electrode of the power supply; the negative electrode of the diode D4 is divided into two paths, which are connected to the positive electrode of the diode D3 and the resistor R23, and the negative electrode of the diode D3 is connected to the primary output end of the linear optocoupler U2; the other end of the resistor R23 is divided into three paths, which are connected in parallel to the 4th pins of the secondary sides of the solid-state relays U4 and U5 and the 3rd pin of the secondary side of the solid-state relay U6, the 3rd pin of the secondary side of the solid-state relay U5 is connected to the PE pole contact of the output end of the relay K1, and the 4th pin of the secondary side of the solid-state relay U6 is connected to the negative reference resistor R4 to ground and then to the negative electrode of the power supply; The secondary input end of the linear optocoupler U2 is connected in parallel to the 13th pin of the control unit U1 and the resistor R22. The secondary input end of the linear optocoupler U3 is connected in parallel to the 12th pin of the control unit U1 and the resistor R24. The secondary output ends of the linear optocouplers U2 and U3 are connected in parallel to the 10th pin of the control unit U1. The other ends of the resistors R22 and R24 are connected to the +5V power supply. The secondary pin 1 of the solid-state relays U4, U5, and U6 are connected to R5, R13, and R6 respectively and then connected in parallel to pin 20 of the control unit U1. Pin 20 of the control unit U1 is also connected to a +5V power supply; the secondary pin 2 of the solid-state relays U4, U5, and U6 are connected to pins 15, 16, and 14 of the control unit U1 respectively.

4. The railway passenger car insulation test device according to claim 3, characterized in that: The positive reference resistor R3 and the negative reference resistor R4 are both composed of two resistors with a resistance value of 2KΩ connected in parallel, and one branch of the positive reference resistor R3 and one branch of the negative reference resistor R4 are connected by a bipolar switch S3.

5. The railway passenger car insulation test device according to claim 4, characterized in that: When the conversion switch (2) is selected to the "leakage current" gear, the bipolar switch S1 is connected, and the bipolar switches S2 and S3 are disconnected; when the conversion switch (2) is selected to the "stop" gear, the bipolar switches S1, S2, and S3 are all disconnected; when the conversion switch (2) is selected to the "DC110V insulation" gear, the bipolar switch S2 is connected, and the bipolar switches S1 and S3 are disconnected; when the conversion switch (2) is selected to the "DC48V insulation" gear, the bipolar switches S2 and S3 are connected, and the bipolar switch S1 is disconnected.

6. The railway passenger car insulation test device according to claim 2, characterized in that: The indicator light board (7) is provided with five indicator lights: a power light LED1, a positive line normal light LED2, a positive line alarm light LED3, a negative line normal light LED4, and a negative line alarm light LED5. The 20-pin of the control unit U1 is connected in parallel to the positive electrode of the power light LED1, resistors R8 and R10, the negative electrode of LED1 is connected to R7, the other end of the resistor R8 is connected in series with the positive electrode of the positive line normal light LED2, the positive electrode of the positive line alarm light LED3 and the resistor R9, the other end of the resistor R10 is connected in series with the positive electrode of the negative line normal light LED4, the positive electrode of the negative line alarm light LED5 and the resistor R11; the other ends of the resistors R7, R9 and R11 are grounded; Pin 1 of the control unit U1 is connected to the resistor R18 and then connected to the ground in parallel with pin 10 of the control unit U1.

7. The railway passenger car insulation test device according to claim 2, characterized in that: The alarm circuit (62) comprises a buzzer (621), the positive electrode of the buzzer (621) is connected to a +10V power supply, and the negative electrode is connected to pin 1 of transistor T1; pin 2 of transistor T1 is divided into two paths, connected to pins 10 and 11 of control unit U1 through resistors R20 and R26 respectively, and pin 3 of transistor T1 is connected to pin 10 of control unit U1; pin 11 of control unit U1 is connected in parallel with a diode D8 and a resistor R19, and the other ends of diode D8 and resistor R19 are connected in parallel with a +5V power supply.

8. The railway passenger car insulation test device according to claim 1, characterized in that: The anti-reverse connection circuit (3) is composed of four diodes forming a bridge structure.

9. The railway passenger car insulation test device according to claim 1, characterized in that: The midpoint resistor (8) includes two line resistors R101 and R102 and a ground resistor RE. The two line resistors R101 and R102 are connected in series and their two ends are respectively connected to the positive and negative lines of the power supply; one end of the ground resistor RE is connected to the wire between the two line resistors R101 and R102, and the other end is connected in series with an ammeter (5) and then connected to the ground wire.

10. The railway passenger car insulation test device according to claim 1, characterized in that: An aluminum heat sink (81) is installed below or above the midpoint resistor (8).

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