Auxiliary Measuring Device for Molded Case Circuit Breaker

Abstract

The present invention discloses an auxiliary measurement device for a molded case circuit breaker, comprising: a closing and opening assembly, a measurement circuit, a first contact assembly, a second contact assembly, a third contact assembly, an electromagnetic mutual inductance assembly, and a shunt release. The closing and opening assembly drives the first contact assembly to closely adhere to the third contact assembly. The second contact assembly is limited within the electromagnetic mutual inductance assembly and is separated from the third contact assembly. The shunt release drives the first contact assembly away from the third contact assembly. The electromagnetic mutual inductance assembly drives the second contact assembly to closely adhere to the third contact assembly. The measurement circuit is connected to the first contact assembly through a first wire, the measurement circuit is connected to the second contact assembly through a second wire, the measurement circuit is connected to the electromagnetic mutual inductance assembly through a third wire, and the electromagnetic mutual inductance assembly is connected to the first contact assembly through a fourth wire. The present invention provides an auxiliary measurement device for a molded case circuit breaker that ensures the safety of the measurement circuit, effectively electrically isolates it from the static contact, and prevents damage to the measurement circuit.

Description

Technical Field

[0001] The present invention relates to the field of circuit breaker equipment, and more particularly to an auxiliary measurement device for a molded case circuit breaker. Background Art

[0002] The development of smart grid has put forward higher and higher requirements for the safe operation of power systems. The reliability of molded case circuit breakers, which play roles of control, protection, monitoring, etc. in power systems, is of crucial importance. The moving contact of a molded case circuit breaker is a key component of the breaker's operating mechanism, and its operating performance directly affects the service life of the entire circuit breaker. After the moving contact and the static contact of the circuit breaker are closed, there is a contact resistance at the contact of the contacts. Due to the reduction of contact pressure, or the oxidation of the metal surface of the contacts, or the damage of the contacts caused by multiple make-and-break operations, the contact resistance of the contacts will increase; when a large current flows through the circuit breaker, it will cause serious heating of the contacts, the self-heating of the circuit breaker will rise, affecting the service life of the circuit breaker and making it difficult to meet the reliability requirements for long-term on-site operation of the circuit breaker; at the same time, poor contact of the contacts will also increase the self-power consumption of the circuit breaker, which is not conducive to the energy-saving operation of the power grid.

[0003] By detecting the contact resistance when the contacts are closed, the contact reliability of the contacts can be judged. The existing measurement of the contact resistance of contacts generally obtains the contact resistance of the contacts by measuring the current flowing through the contacts and measuring the voltage across the contacts and then calculating.

[0004] When the circuit breaker is closed, the moving and static contacts are closed, and the voltage difference across the contacts is very small. A measurement circuit can be used to sample and measure the two voltages across the contacts respectively; when the circuit breaker is manually opened or opened by protection, the moving and static contacts are separated. At this time, there is a high voltage of 220V / or 380V between the moving and static contacts, and the same high voltage also exists at the two measurement points, and the measurement circuit will be damaged by the high voltage breakdown. Therefore, when measuring the voltage across the contacts, the two voltage measurement circuits need to have electrical isolation measures. The existing technologies generally use voltage transformers or two voltage measurement circuits with electrical isolation, etc. These technologies have the following main problems:

[0005] 1. After the circuit breaker is opened, to meet the requirements of the dielectric performance test between the incoming line end and the outgoing line end of the circuit breaker, when using a voltage transformer, the withstand voltage value between the primary and secondary of the transformer should reach more than 2kV. Therefore, the production process of the voltage transformer is complex, the volume of the transformer is large, it is not convenient for installation, and the cost is high.

[0006] 2. Using two voltage measurement circuits with electrical isolation adds extra devices such as measurement circuits, isolation power supplies, optocouplers, etc. The circuit is complex and the cost is high. There are many internal wirings in the circuit breaker, which is not convenient for production.

[0007] 3. When using a measurement circuit, voltage sampling point isolation control devices such as relays need to be added to control the disconnection and closure of the measurement channels, which requires the participation of software. Delayed isolation control or incorrect control strategies may cause isolation failure and damage to the measurement circuit. Therefore, high requirements are imposed on the real-time performance and reliability of the software.

[0008] 4. When the circuit breaker is manually tripped or protected from tripping, the software needs to be able to detect the trend of the handle change and the signal of the protection action in real time, and quickly control the isolation device to ensure that the voltage measurement channel is disconnected before the contacts are separated. Therefore, the difficulty of software programming is greatly increased, and high requirements are imposed on the action speed of the control circuit.

[0009] How to ensure the safe and reliable measurement of the voltage across the contacts and prevent damage to the measurement circuit caused by isolation failure is the problem to be solved by the present invention. Summary of the Invention

[0010] To solve the above problems, the object of the present invention is to provide an auxiliary measurement device for a molded case circuit breaker that can ensure the safe and effective electrical isolation of the measurement circuit from the static contact and prevent damage to the measurement circuit.

[0011] According to one aspect of the present invention, there is provided an auxiliary measurement device for a molded case circuit breaker, including: a closing and opening assembly, a measurement circuit, a first contact assembly, a second contact assembly, a third contact assembly, an electromagnetic mutual inductance assembly, and a shunt trip. The closing and opening assembly drives the first contact assembly to press against the third contact assembly. The second contact assembly is limited within the electromagnetic mutual inductance assembly and is separated from the third contact assembly. The shunt trip drives the first contact assembly away from the third contact assembly. The electromagnetic mutual inductance assembly drives the second contact assembly to press against the third contact assembly. The measurement circuit is connected to the first contact assembly through a first wire, the measurement circuit is connected to the second contact assembly through a second wire, the measurement circuit is connected to the electromagnetic mutual inductance assembly through a third wire, and the electromagnetic mutual inductance assembly is connected to the first contact assembly through a fourth wire.

[0012] In some embodiments, the closing and opening assembly includes: a handle, a curved rod, and a connecting rod. A first rotating shaft is provided in the middle of the curved rod. The handle drives the top of the curved rod to drive the bottom of the curved rod to rotate along the first rotating shaft. The bottom of the curved rod is connected to the first contact assembly. A second rotating shaft is provided in the middle of the connecting rod. The handle drives the top of the connecting rod to drive the bottom of the connecting rod to rotate along the second rotating shaft. The bottom of the connecting rod is connected to the second contact assembly.

[0013] In some embodiments, the first contact assembly includes: a first mounting block, a third rotating shaft, and a moving contact. The moving contact is fixedly arranged at the bottom of the front end of the first mounting block. The rear end of the first mounting block is connected to the front end of a curved rod through a hinge. The third rotating shaft is arranged in the middle of the first mounting block. The curved rod drives the moving contact to rotate around the third rotating shaft. A first voltage sampling point is provided on the moving contact. The first voltage sampling point is connected to a measurement circuit through a first wire. The first contact assembly is connected to the electromagnetic mutual induction assembly through a fourth wire.

[0014] In some embodiments, the second contact assembly includes: a pull rod, a probe, a driving spring, and a housing. The pull rod and the driving spring are arranged inside the housing. The probe is fixed at the front end of the pull rod. The driving spring presses the probe into the housing.

[0015] In some embodiments, a sliding groove is provided at the rear end of the pull rod. The bottom of the connecting rod is arranged in the sliding groove through a pin. The shunt release drives the ejector rod to press the connecting rod, thereby driving the probe away from the third contact assembly.

[0016] In some embodiments, the probe is made of a conductive material. The rear end of the probe is connected to the measurement circuit through a second wire.

[0017] In some embodiments, the electromagnetic mutual induction assembly includes: a coil, a current transformer, and an incoming line terminal block. The current transformer is sleeved on the incoming line terminal block. The current transformer is connected to the measurement circuit through a third wire. The coil is arranged at the front end of the incoming line terminal block.

[0018] In some embodiments, the third contact assembly includes: a second mounting block, a static contact, and a recess. The static contact is provided at the top of the second mounting block. The static contact is located on the moving path of the moving contact. A recess is provided on the side of the second mounting block. A second voltage sampling point is provided in the recess.

[0019] In some embodiments, the coil is sleeved outside the housing. The coil drives the probe to press into the recess.

[0020] In some embodiments, the recess matches the probe.

[0021] Compared with the prior art, the present invention has the beneficial effects of an auxiliary measuring device for a molded case circuit breaker that can ensure the safety of the measurement circuit, effectively electrically isolate the static contact, and prevent damage to the measurement circuit. Through the cooperation of the first contact assembly, the second contact assembly, the electromagnetic mutual induction assembly, and the measurement circuit, it is ensured that when closing the switch, the moving contact and the static contact can be closed first, and when the current passing through the circuit breaker is greater than a certain value, the measurement circuit is connected to the static contact, so as to ensure safe and reliable measurement of the voltage across the contacts. When opening the switch, the measurement circuit can be disconnected from the static contact first, and the moving contact and the static contact can be disconnected later, ensuring that the measurement circuit is safely and effectively electrically isolated from the static contact and preventing damage to the measurement circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of the auxiliary measurement device of the molded case circuit breaker of the present invention;

[0023] Figure 2 It is a schematic structural diagram of the closing and opening component of the auxiliary measurement device of the molded case circuit breaker of the present invention;

[0024] Figure 3 It is a schematic structural diagram of the first contact component of the auxiliary measurement device of the molded case circuit breaker of the present invention;

[0025] Figure 4 It is a schematic structural diagram of the electromagnetic mutual inductance component of the auxiliary measurement device of the molded case circuit breaker of the present invention;

[0026] Figure 5 It is a schematic structural diagram of the third contact component of the auxiliary measurement device of the molded case circuit breaker of the present invention;

[0027] Figure 6 It is a schematic structural diagram of the second contact component of the auxiliary measurement device of the molded case circuit breaker of the present invention. Detailed implementation manners

[0028] The present invention will be described in detail below in conjunction with the various implementation manners shown in the drawings. However, it should be noted that these implementation manners are not limitations on the present invention. Any equivalent transformation or substitution in terms of function, method or structure made by those of ordinary skill in the art according to these implementation manners shall fall within the protection scope of the present invention.

[0029] In the description of the present invention, it should be noted that unless otherwise specified and defined, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or the communication inside two components. It can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific situations.

[0030] Such as Figure 1As shown in the figure, the auxiliary measurement device of the molded case circuit breaker of the present invention includes: a closing and opening assembly 1, a measurement circuit 2, a first contact assembly 3, a second contact assembly 4, a third contact assembly 5, an electromagnetic mutual inductance assembly 6, and a shunt release 7. The closing and opening assembly 1 drives the first contact assembly 3 to be in close contact with the third contact assembly 5. The second contact assembly 4 is limited within the electromagnetic mutual inductance assembly 6 and is separated from the third contact assembly 5. The shunt release 7 drives the first contact assembly 3 away from the third contact assembly 5. The electromagnetic mutual inductance assembly 6 drives the second contact assembly 4 to be in close contact with the third contact assembly 5. The measurement circuit 2 is connected to the first contact assembly 3 through a first wire 8, the measurement circuit 2 is connected to the second contact assembly 4 through a second wire 9, the measurement circuit 2 is connected to the electromagnetic mutual inductance assembly 6 through a third wire 10, and the electromagnetic mutual inductance assembly 6 is connected to the first contact assembly 3 through a fourth wire 20. Through the cooperation of the first contact assembly 3, the second contact assembly 4, the electromagnetic mutual inductance assembly 6, and the measurement circuit 2, it is ensured that during closing, the moving contact 33 and the static contact 52 can be closed first, and when the current passing through the circuit breaker is greater than a certain value, the measurement circuit 2 is connected to the static contact 52, so as to ensure safe and reliable measurement of the voltage across the contacts; during opening, the measurement circuit 2 can be disconnected from the static contact 52 first, and the moving contact 33 and the static contact 52 are disconnected later, ensuring that the measurement circuit 2 is safely and effectively electrically isolated from the static contact 52 and preventing damage to the measurement circuit 2.

[0031] As Figure 2 shown, the closing and opening assembly 1 includes: a handle 11, a curved rod 12, and a connecting rod 13. A first rotating shaft 14 is provided in the middle of the curved rod 12. The handle 11 drives the top of the curved rod 12 to drive the bottom of the curved rod 12 to rotate along the first rotating shaft 14. The bottom of the curved rod 12 is connected to the first contact assembly 3; a second rotating shaft 15 is provided in the middle of the connecting rod 13. The handle 11 drives the top of the connecting rod 13 to drive the bottom of the connecting rod 13 to rotate along the second rotating shaft 15. The bottom of the connecting rod 13 is connected to the second contact assembly 4. When the handle 11 is pulled to the right, the handle 11 pushes the curved rod 12 to rotate along the first rotating shaft 14, thereby realizing the contact and closing of the moving contact 33 and the static contact 52; when the handle 11 is continuously pulled, the curved rod 12 pushes the connecting rod 13; the connecting rod 13 moves around the second rotating shaft 15, and the other end of the connecting rod 13 moves leftward in the sliding groove 45 of the pull rod 41, reserving the stroke for the pull rod 41 to move leftward; when the handle 11 is continuously pulled to the closing position, the moving contact 33 and the static contact 52 are completely closed.

[0032] As Figure 3As shown in the figure, the first contact assembly 3 includes: a first mounting block 31, a third rotating shaft 32, and a moving contact 33. The moving contact 33 is fixedly arranged at the bottom of the front end of the first mounting block 31. The rear end of the first mounting block 31 is connected to the front end of the curved rod 12 through a hinge. The third rotating shaft 32 is arranged in the middle of the first mounting block 31. The curved rod 12 drives the moving contact 33 to rotate around the third rotating shaft 32. A first voltage sampling point 34 is arranged on the moving contact 33, and the first voltage sampling point 34 is connected to the measuring circuit 2 through a first wire 8. By driving the first mounting block 31 with the curved rod 12, the first mounting block 31 rotates around the third rotating shaft 32, realizing the closing of the moving contact 33 and the static contact 52. The voltage of the sampling point of the moving contact 33 is supplied to the measuring circuit 2 through the first wire 8. The mechanism design ensures that when closing, the moving contact 33 and the static contact 52 are closed first.

[0033] As Figure 4 shown in the figure, the electromagnetic mutual induction assembly 6 includes: a coil 61, a current transformer 62, and an incoming line terminal block 63. The current transformer 62 is sleeved on the incoming line terminal block 63. The current transformer 62 is connected to the measuring circuit 2 through a third wire 10. The coil 61 is arranged at the front end of the incoming line terminal block 63. When the current flowing through the coil 61 is greater than a fixed value, the induced magnetic force is greater than the force of the driving spring 43. The magnetic force pushes the probe 42 to move leftward and touches the depression 53 at the voltage sampling point on the static contact 52. When the probe 42 moves leftward, it pulls the pull rod 41 to move leftward. The greater the current in the coil 61, the greater the magnetic thrust and the greater the pressure of the probe 42, ensuring reliable contact between the probe 42 and the static contact 52. The front end of the coil 61 is connected to the first contact assembly 3 through a fourth wire 20.

[0034] The coil 61 is sleeved outside the housing 44, and the coil 61 drives the probe 42 to press into the depression 53.

[0035] As Figure 5 shown in the figure, the third contact assembly 5 includes: a second mounting block 51, a static contact 52, and a depression 53. The static contact 52 is arranged at the top of the second mounting block 51. The static contact 52 is located on the moving path of the moving contact 33. A depression 53 is arranged on the side of the second mounting block 51, and a second voltage sampling point 54 is arranged in the depression 53. Through the second voltage sampling point 54, it is convenient to complete voltage sampling.

[0036] As Figure 6 shown in the figure, the second contact assembly 4 includes: a pull rod 41, a probe 42, a driving spring 43, and a housing 44. The pull rod 41 and the driving spring 43 are arranged inside the housing 44. The probe 42 is fixedly arranged at the front end of the pull rod 41. The driving spring 43 presses the probe 42 into the housing 44. In the initial state, the driving spring 43 confines the pull rod 41 and the probe 42 inside the housing 44, keeping the probe 42 separated from the depression 53.

[0037] A sliding groove 45 is provided at the rear end of the drawbar 41, and the bottom of the connecting rod 13 is arranged in the sliding groove 45 through a pin; the shunt release 7 drives the ejector rod to press the connecting rod 13, thereby driving the probe 42 away from the third contact assembly 5.

[0038] The probe 42 is made of a conductive material, and the rear end of the probe 42 is connected to the measurement circuit 2 through the second wire 9. Only when the probe 42 is conductive can the above measurement be completed.

[0039] The recess 53 matches the probe 42. The shape of the recess 53 is designed to be similar to the shape of the tip of the probe 42 so that the two match, ensuring reliable contact between the probe 42 and the static contact 52; the voltage at the sampling point of the static contact 52 is supplied to the measurement circuit 2 through the second wire 9 on the probe 42. The measurement circuit 2 measures and calculates the current and the two voltages at both ends of the contact to obtain the contact resistance at the contact, thereby judging the contact reliability of the contact. When the current is less than a certain value or there is no current, the probe 42 retracts under the action of the driving spring 43 and returns to the origin.

[0040] In specific implementation:

[0041] 1. Pull the handle 11 in the closing direction (to the right). The structure of the handle 11 ensures that the curved rod 12 is first pushed. The curved rod 12 rotates around the first rotating shaft 14, and finally drives the first mounting block 31 to further push the moving contact 33 to move towards the static contact 52 around the third rotating shaft 32. The moving contact 33 and the static contact 52 start to close; continue to pull the handle 11, and the curved rod 12 pushes the connecting rod 13; the connecting rod 13 moves around the second rotating shaft 15, and the other end of the connecting rod 13 moves leftward in the sliding groove 45 of the drawbar 41, reserving the stroke for the drawbar 41 to move leftward. Continue to pull the handle 11 to the closing position, and the moving contact 33 and the static contact 52 are completely closed. The voltage at the sampling point of the moving contact 33 is supplied to the measurement circuit 2 through the first wire 8. The mechanism design ensures that the contacts close first during closing.

[0042] 2. After the circuit breaker is closed and there is no current flowing through the circuit breaker, there is no current in the coil 61, no magnetic induction, and the probe 42 is maintained at the origin under the action of the driving spring 43 and will not extend.

[0043] 3. After the circuit breaker is closed and there is current flowing through it, the current flows from the incoming line terminal block 63 to the coil 61, then to the moving contact 33 and the static contact 52. The current induced in the secondary of the current transformer 62 is supplied to the measurement circuit 2. When the current flowing through the coil 61 is greater than a certain value, the induced magnetic force is greater than the force of the spring 43. The magnetic force pushes the probe 42 to move leftward and presses against the depression 53 at the second voltage sampling point 54 on the static contact 52. When the probe 42 moves leftward, it pulls the pull rod 41 to move leftward. The greater the current in the coil 61, the greater the magnetic thrust and the greater the pressure of the probe 42, ensuring reliable contact between the probe 42 and the static contact 52. The shape of the depression 53 is designed to match the shape of the tip of the probe 42, ensuring reliable contact between the probe 42 and the static contact 52. The voltage at the sampling point of the static contact 52 is supplied to the measurement circuit 2 through the second wire 9 on the probe 42. The measurement circuit 2 measures and calculates the current and the two voltages across the contacts to obtain the contact resistance at the contacts, thereby enabling the judgment of the contact reliability of the contacts. When the current is less than the certain value or there is no current, the probe 42 retracts under the action of the spring 43 force and returns to the origin.

[0044] 4. Pull the handle 11 in the opening direction (leftward). The structure of the handle 11 ensures that it first pushes the connecting rod 13. The connecting rod 13 moves around the second rotating shaft 15. The other end of the connecting rod 13 moves rightward in the sliding groove 45 at the rear end of the pull rod 41 and pulls the pull rod 41 to move rightward. The pull rod 41 drives the probe 42 to move rightward, and the probe 42 leaves the sampling point of the static contact 52, forming electrical isolation between the probe 42 and the static contact 52. Continue to pull the handle 11, and the connecting rod 13 pushes the curved rod 12. The curved rod 12 moves around the first rotating shaft 14, driving the moving contact 33 to move, and the moving contact 33 starts to disconnect from the static contact 52. Continue to pull the handle 11 to the opening position, and the moving contact 33 is completely disconnected from the static contact 52. The mechanism design ensures that when opening the switch, the probe 42 first leaves the static contact 52 to form electrical isolation, and then the contacts disconnect.

[0045] 5. When the protection trips, the shunt trip 7 operates, and the ejector rod on the shunt trip 7 is ejected, pushing the handle 11 to move in the opening direction (leftward). The structure of the handle 11 ensures that it first pushes the connecting rod 13. The connecting rod 13 moves around the second rotating shaft 15. The other end of the connecting rod 13 moves rightward in the sliding groove 45 at the rear end of the pull rod 41 and pulls the pull rod 41 to move rightward. The pull rod 41 drives the probe 42 to move rightward, and the probe 42 leaves the voltage sampling point of the static contact 52, forming electrical isolation between the probe 42 and the static contact 52. The ejector rod continues to push the handle 11, and the connecting rod 13 pushes the curved rod 12. The curved rod 12 moves around the first rotating shaft 14, driving the moving contact 33 to move, and the moving contact 33 starts to disconnect from the static contact 52. The ejector rod continues to push the handle 11 to the opening position, and the moving contact 33 is completely disconnected from the static contact 52.

[0046] The above are only some embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, other deformations and improvements can also be made, and these all belong to the protection scope of the present invention.

Claims

1. Auxiliary measuring device for molded case circuit breaker, characterized in that Comprising: A switching-on and -off assembly, a measuring circuit, a first contact assembly, a second contact assembly, a third contact assembly, an electromagnetic mutual inductance assembly, and a shunt trip. The switching-on and -off assembly drives the first contact assembly to press against the third contact assembly. The second contact assembly is confined within the electromagnetic mutual inductance assembly and is separated from the third contact assembly. The shunt trip drives the first contact assembly away from the third contact assembly. The electromagnetic mutual inductance assembly drives the second contact assembly to press against the third contact assembly. The measuring circuit is connected to the first contact assembly through a first wire, the measuring circuit is connected to the second contact assembly through a second wire, the measuring circuit is connected to the electromagnetic mutual inductance assembly through a third wire, and the electromagnetic mutual inductance assembly is connected to the first contact assembly through a fourth wire.

2. The auxiliary measuring device of the molded case circuit breaker according to claim 1, characterized in that The switching-on and -off assembly includes: a handle, a curved rod, and a connecting rod. A first rotating shaft is provided in the middle of the curved rod. The handle drives the top of the curved rod to drive the bottom of the curved rod to rotate along the first rotating shaft. The bottom of the curved rod is connected to the first contact assembly. A second rotating shaft is provided in the middle of the connecting rod. The handle drives the top of the connecting rod to drive the bottom of the connecting rod to rotate along the second rotating shaft. The bottom of the connecting rod is connected to the second contact assembly.

3. The auxiliary measuring device of the molded case circuit breaker according to claim 2, characterized in that, The first contact assembly includes: a first mounting block, a third rotating shaft, and a moving contact. The moving contact is fixedly provided at the bottom of the front end of the first mounting block. The rear end of the first mounting block is connected to the front end of the curved rod through a hinge. The third rotating shaft is provided in the middle of the first mounting block. The curved rod drives the moving contact to rotate around the third rotating shaft. A first voltage sampling point is provided on the moving contact. The first voltage sampling point is connected to the measuring circuit through a first wire. The first contact assembly is connected to the electromagnetic mutual inductance assembly through a fourth wire.

4. The auxiliary measuring device of the plastic case circuit breaker according to claim 3, characterized in that, The second contact assembly includes: a pull rod, a probe, a driving spring, and a housing. The pull rod and the driving spring are provided inside the housing. The front end of the pull rod is fixed with the probe. The driving spring presses the probe into the housing.

5. The auxiliary measuring device of the plastic case circuit breaker according to claim 4, characterized in that, A sliding groove is provided at the rear end of the pull rod. The bottom of the connecting rod is provided in the sliding groove through a pin. The shunt trip drives a push rod to press the connecting rod and further drives the probe away from the third contact assembly.

6. The auxiliary measuring device of the plastic case circuit breaker according to claim 4, characterized in that, The probe is made of a conductive material. The rear end of the probe is connected to the measuring circuit through a second wire.

7. The auxiliary measuring device of the molded case circuit breaker according to claim 4, characterized in that The electromagnetic mutual inductance assembly includes: a coil, a current transformer, and an incoming line terminal block. The current transformer is sleeved on the incoming line terminal block. The current transformer is connected to the measuring circuit through a third wire. A coil is provided at the front end of the incoming line terminal block.

8. The auxiliary measuring device of the molded case circuit breaker according to claim 7, characterized in that, The third contact assembly includes: a second mounting block, a static contact, and a recess. The static contact is provided at the top of the second mounting block. The static contact is located on the moving path of the moving contact. A recess is provided on the side of the second mounting block. A second voltage sampling point is provided in the recess.

9. The auxiliary measuring device of the molded case circuit breaker according to claim 8, characterized in that The coil is sleeved outside the housing. The coil drives the probe to press into the recess.

10. The auxiliary measuring device of the molded case circuit breaker according to claim 8, characterized in that, The recess matches the probe.

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