CN209981147U

CN209981147U - TMD and molded case circuit breaker

Info

Publication number: CN209981147U
Application number: CN201921338757.6U
Authority: CN
Inventors: 刘振忠; 西蒙田
Original assignee: Schneider Electric China Co Ltd
Current assignee: Schneider Electric China Co Ltd
Priority date: 2019-08-16
Filing date: 2019-08-16
Publication date: 2020-01-21
Anticipated expiration: 2029-08-16

Abstract

The utility model discloses a TMD, which comprises a bimetallic strip and a switch circuit; the switch circuit is connected with the bimetallic strip in parallel and is used for being communicated when the TMD is subjected to short-circuit breaking. The TMD utilizes a switch circuit to be connected with the bimetallic strip in parallel and is used for separating a part of short-circuit energy from the bimetallic strip during short circuit, ensuring that the energy flowing through the bimetallic strip is less than the allowable value thereof, preventing the bimetallic strip from being excessively deformed and damaged and successfully passing a short-circuit test; meanwhile, the bimetallic strip in the TMD bears small current during a short-circuit test, so that excessive deformation is avoided, the deflection design is not required to be changed, and good tripping performance is ensured during normal work. The utility model also discloses a moulded case circuit breaker, its above-mentioned TMD of using can pass through the short circuit test, guarantees again to possess good dropout performance at normal during operation.

Description

TMD and molded case circuit breaker

Technical Field

The utility model relates to an electric product technical field, more specifically say, relate to a TMD, still relate to a medium-sized circuit breaker.

Background

The small current TMD (Thermal Magnetic Device, Thermal trip) in the molded case circuit breaker is not good in tripping performance or difficult to pass a short circuit test because the high deflection requirement of the bimetallic strip under the normal working condition is contradictory with the requirement of no excessive deformation during short circuit breaking.

Therefore, how to ensure the high flexibility of the bimetal in the TMD under normal working conditions and ensure that the bimetal has good tripping performance, and avoid the bimetal from being damaged due to too large current when in short circuit, and ensure that the bimetal passes through a short circuit test is a problem to be solved urgently by those skilled in the art.

SUMMERY OF THE UTILITY MODEL

In view of the above, the present invention provides a TMD, which utilizes a switching circuit connected in parallel with a bimetal, and is used to separate a part of short-circuit energy from the bimetal during short circuit, so as to ensure that the energy flowing through the bimetal is less than the allowable value thereof, prevent the bimetal from being excessively deformed and damaged, and successfully pass a short-circuit test; meanwhile, the bimetallic strip in the TMD bears small current during a short-circuit test, so that excessive deformation is avoided, the deflection design is not required to be changed, and good tripping performance is ensured during normal work. The utility model also provides a moulded case circuit breaker, its above-mentioned TMD of using can pass through the short circuit test, guarantees again to possess good dropout performance at normal during operation.

In order to achieve the above object, the utility model provides a following technical scheme:

a TMD, comprising:

a bimetal;

and the switching circuit is connected with the bimetallic strip in parallel and is used for being communicated when the TMD is subjected to short-circuit breaking.

Preferably, in the TMD described above, the switching circuit is turned on by an electromotive force generated by a pigtail between the bimetal and a thermal element of the TMD when a short-circuit current passes.

Preferably, in the TMD, the switch circuit is configured to shunt at least one third of total energy flowing through the bimetal when the short circuit is broken.

Preferably, the TMD further includes a reset elastic element configured to drive the switching circuit to be turned off after the electromotive force disappears.

A molded case circuit breaker comprises a TMD, wherein the TMD is the TMD in any one of the technical schemes.

The utility model provides a TMD, which comprises a bimetallic strip and a switch circuit; the switch circuit is connected with the bimetallic strip in parallel and is used for being communicated when the TMD is subjected to short-circuit breaking.

The utility model provides a TMD, it utilizes switch circuit and bimetallic strip to connect in parallel, is used for separating some short circuit energy from bimetallic strip when the short circuit, guarantees that the energy that flows through bimetallic strip is less than its permissible value, prevents that bimetallic strip from taking place excessive deformation and damaging, passes through the short circuit test smoothly; meanwhile, the bimetallic strip in the TMD bears small current during a short-circuit test, so that excessive deformation is avoided, the deflection design is not required to be changed, and good tripping performance is ensured during normal work.

The utility model also provides a moulded case circuit breaker, its above-mentioned TMD of using can pass through the short circuit test, guarantees again to possess good dropout performance at normal during operation.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a TMD according to an embodiment of the present invention before a short circuit test is performed;

fig. 2 is a schematic structural diagram of a TMD according to an embodiment of the present invention after a short circuit test is performed;

fig. 3 is a schematic circuit diagram of a TMD according to an embodiment of the present invention;

wherein, in fig. 1-3:

a bimetal 101; a switching circuit 102.

Detailed Description

The embodiment of the utility model discloses TMD, it utilizes switch circuit and bimetallic strip to connect in parallel for partly remove the short circuit energy from bimetallic strip when the short circuit, guarantee that the energy of flowing through bimetallic strip is less than its allowable value, prevent that bimetallic strip from taking place excessive deformation and damaging, pass the short circuit test smoothly; meanwhile, the bimetallic strip in the TMD bears small current during a short-circuit test, so that excessive deformation is avoided, the deflection design is not required to be changed, and good tripping performance is ensured during normal work. The embodiment of the utility model provides a still disclose a moulded case circuit breaker, its above-mentioned TMD of using can pass through the short circuit test, guarantees again to possess good dropout performance at normal during operation.

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Referring to fig. 1-3, an embodiment of the present invention provides a TMD, which includes a bimetal 101 and a switch circuit 102; the switching circuit 102 is connected in parallel to the bimetal 101 and is used to be connected when the TMD is short-circuited.

The embodiment of the utility model provides a TMD, it utilizes switch circuit 102 to connect in parallel with bimetallic strip 101 for when the short circuit is used for separating a part of short circuit energy from bimetallic strip 101, guarantees that the energy that flows through bimetallic strip 101 is less than its permissible value, prevents that bimetallic strip 101 from taking place excessive deformation and damaging, passes through the short circuit test smoothly; meanwhile, the bimetallic strip 101 in the TMD bears small current during a short-circuit test, so that excessive deformation is avoided, the deflection design is not required to be changed, and good tripping performance is ensured during normal work.

Specifically, in the TMD described above, the switch circuit 102 is turned on by an electromotive force generated when a short-circuit current passes through a pigtail between the bimetal 101 and a thermal element of the TMD. The switching circuit 102 is adapted to shunt at least one third of the total energy flowing through the bimetal strip 101 when the short circuit is broken.

Further, as in the TMD, a reset elastic element is further included, and the reset elastic element is used for driving the switch circuit 102 to be turned off after the electrodynamic force disappears. Of course, the switch circuit 102 may be blown by the current passing through the circuit when the short circuit occurs for the second time, and the opening and closing manner of the switch circuit 102 is not limited in this embodiment.

When the TMD provided by this embodiment is in normal operation, the switching circuit 102 connected in parallel with the bimetal 101 is in a disconnected state, a load current flows through the bimetal 101 to heat and bend the bimetal, and when the load current exceeds a threshold value and lasts for a preset time, the bending deflection pushes the trip bar to trip and open the molded case circuit breaker. In the case of the above TMD short circuit, when a short circuit current flows through the soft pigtail, the electrical force causes the pigtail to extend outward, the pushed switch circuit 102 is closed or the pigtail is directly connected to the switch circuit 102, so as to form an energy release circuit, which shunts the current that should flow through the bimetal 101, thereby protecting the bimetal 101 from being damaged during the short circuit.

The TMD provided in this embodiment not only maintains the high deflection of the bimetal 101 under normal operating conditions, but also uses the leakage of the switching circuit 102 to remove a part of the short-circuit energy from the bimetal 101 during short-circuit, thereby ensuring that the energy flowing through the bimetal 101 is less than its allowable value. Meanwhile, the switch circuit 102 occupies a small space, and the switch circuit is switched on by using the electric force generated by the pigtail of the bimetal 101 and the thermal element when the short-circuit current passes through, so that the switch circuit 102 is simple and reliable. Specifically, the TMD is a low current TMD.

The embodiment of the utility model provides a moulded case circuit breaker is still provided, including TMD, wherein TMD is the TMD that above-mentioned embodiment provided.

The moulded case circuit breaker that this embodiment provided uses above-mentioned TMD, can pass through the short circuit test, guarantees again to possess good dropout performance when normal operating. Of course, the molded case circuit breaker provided in this embodiment further has other effects related to TMD provided in the above embodiments, and details are not described herein.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A TMD, comprising:

a bimetal;

2. The TMD of claim 1, wherein the switch circuit is completed by an electro-motive force generated by a pigtail between the bimetallic strip and a thermal element of the TMD when a short circuit current is passed.

3. The TMD of claim 2, wherein the switching circuit is configured to shunt at least one third of a total energy through the bimetal when a short circuit is broken.

4. The TMD of claim 2, further comprising a return spring for driving the switching circuit open after the loss of the electrodynamic force.

5. A molded case circuit breaker comprising a TMD, wherein the TMD is the TMD of any one of claims 1 to 4.