SU1327201A1 - Circuit breaker thermal element - Google Patents

Abstract

The invention relates to electrical engineering, in particular to elements of automatic circuit breakers, and is intended to increase the reliability of operation at short-circuit currents. The aim of the invention is to increase reliability and reduce dimensions. The thermal element contains current-carrying conductors 1, 10, bimetallic plate 3, thermal storage in the form of two, metal plates 5, heater 6, two insulating plates 7 made of a material with a high thermal conductivity coefficient. The metallic and insulating plates 5, 7 and the heater 6 are assembled into a package using crimp clips 8. 1 Cp. f-ly, il. U & (L

Description

The invention relates to electrical engineering, in particular, to elements of automatic switches, and is intended to improve reliability at high multiplicities of short circuit currents.

The purpose of the invention is to increase reliability and reduce size.

FIG. 1 shows the thermal element of the circuit breaker, general view; in fig. 2 - belt heater with cutouts.

The thermal element of the circuit breaker contains a current lead 1., rigidly connected at site 2 with a bimetallic plate 3, mechanically connected at site 4 with a metal plate 5. Two metal plates 5 together with heater 6 and the heater must reliably operate. The small plates 7 are connected to the package using crimp clips 8. The metal plates 5 and the heater 6 are electrically connected by a conductor 9. The current is supplied to the heater 6 by means of a current lead 10. Between a bimetallic staste 3 and one of the metal plates 5 installed gasket 11.

Thermal element circuit breaker works as follows.

The current flows through the current lead 1 and the hard connection 2 to the bimetallic plate 3 and then through the mechanical connection 4, the metal plate 5, the conductor 9 and the heater 6 to the current lead 10 .. The heating of the bimetallic plate 3 occurs as by its heating current, and due to the transfer of heat from one of the metal plates 5 to it. When the current reaches a certain value, the bimetallic plate 3 bends so that its deformation leads to the operation of the automatic switch.

Since the heater forms a larger total area of contact with the metal plates and is pressed against them with crimp clips, and the insulation plates are made of a thin Layer of flexible or brittle material with a high thermal conductivity coefficient, heat transfer is achieved to metal plates that may be of any thickness. Therefore, at large multiples of short-circuit currents, they cool the heater and allow it to be simple and compact, as well as optimally match the time of the current characteristics of the circuit breaker with the 3-protected object. Effective heat absorption by the heater in this device also allows it to be made of a material with a positive temperature coefficient of resistance. In this case, a greater power output of the heater is achieved at high currents and less when the heaters are smaller compared to thermostable heaters, i.e., a better separation of the nominal mode is achieved, when the circuit breaker does not have to operate, from the overload mode, when the automatic switch is off

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The heater is cheaper (iron, aluminum).

The main disadvantage of the known thermal relay is destruction at short circuit currents due to the presence of insulating plates made of a material with high thermal conductivity, which allows fast transfer of heat from the heater to the metal plates due to effective heat absorption by the metal plates as well as by placing one of the metal plates (as a heat shield) between the heater and the bimetallic plate.

The effective cooling achieved in this thermal element allows a ribbon heater with shaped notches providing any of its specified resistance (Fig. 2). Making the heater and heat accumulator in the form of plates, allowing them to be packaged with crimp clips, reduces the size of the thermal element.

Claims (2)

1. A thermal element of a circuit breaker containing a bimetallic plate, a heater, a heat store mechanically connected to the bimetallic plate and a heater shaped in form, which is placed inside the heat accumulator in isolation from it and located along the bimetallic plate, current leads, one of which is heated on the heater, characterized in that, in order to increase reliability and reduce its dimensions, it is provided with brackets, the heater is plate-shaped, the heat store is made in the form of two metal plates, one of which is located between the bimetallic plate and the heater, while it is mechanically connected to the bimetallic plate and electrically connected to the heater, the insulation of the heat storage from the heater is made in the form of /; Vuh plates of material with a large 15 resistivity. thermal conductivity coefficient, each of which is located between the heater and the corresponding metal plate, with the metal plates, the insulating plates and the heater are connected in a package and installed with brackets, and the other current lead is located on the bimetallic plate. 2. Element pop. 1, which is also distinguished by the fact that the plate heater is made of a material with a positive temperature coefficient Editor M.Petrova Compiled by V.Konosov Tehred L. Oliynyk Proofreader A.Zimokosov Order 3403/50 Circulation 698 Subscription VNIIPI USSR State Committee on affairs of inventions and discoveries 113035, Moscow, Zh-35, Raushsk., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 FIG. 2