SU995147A1 - Thermal indirect-heating disconnector - Google Patents

Description

(54) THERMAL DISCHARGE CONVERSE OF INDIRECT HEATING

one

The invention relates to electrical engineering, to electrical apparatus, in particular to automatic switches.

Known thermal trip indirect heating, mainly on large currents, in which the heater is made movable on the frame, articulated with bimetallic plate 1.

The disadvantage of this release is the increased power consumption due to the heating of the bimetallic plate in the space limited by the hinge.

Also known is a thermal heater for indirect heating, which contains a thermo-bimetallic plate connected to a heater with a flexible joint made of a material with high thermal conductivity, for example copper tape 2.

The disadvantage of this release is the increased power consumption due to the limited thermal contact area between the heater and the thermo-bimetallic plate.

The closest to the proposed technical entity is a thermal heater for indirect heating, mainly for circuit breakers, containing a temperature-sensitive element rigidly fixed at one end and installed with the ability to influence the other end on the control mechanism,

5 and the heater with current leads 3.

A disadvantage of the known thermal release of indirect heating is the dependence of the heating of the thermosensitive element on the magnitude of its deformation, i.e. when heated, the thermo sensitive element

 deforms and moves away from the heater, as a result of which the heating of the temperature-sensitive element is reduced. Thus, heating the temperature-sensitive element to the response temperature requires an additional 5 power consumption.

The temperature of operation of the temperature-sensitive element, regardless of the magnitude of the rated current, is always the same and is determined by the expression

E

t - K tf

(i;

I - "V - S

where K is a constant value;

Claims (3)

Rd is the multiplicity of the overload current setting to the rated current; 1y) - rated current; P is the electrical resistivity of the material of the heater; t, S - length and cross section of the heater, respectively; tcp is the trip time. The tripping time of the release is determined by the requirements for the circuit breakers and, regardless of the magnitude of the rated current, must not exceed a certain value tj, i.e., 1can be considered a constant. To reach the response temperature of the release at different values of the rated current during indirect heating, it is possible to select the specific electrical resistance, i.e., the material, length and cross section of the heater. The cross section of the heater is determined by the magnitude of the rated current and the heat resistance of the heater material, therefore its selection is in a limited range of yum. This also applies to the choice of heater material. Changes in heating temperature due to changes in the length of the heater are also limited by the size of the temperature-sensitive element (width and length). As can be seen from expression (1), when the nominal current decreases, for example, from 16 A to 1.6 A, i.e., 10 times, to reach 1: the same response temperature requires an increase in the product I - | - 100 time. All this greatly complicates the technology of fabrication of heaters for different response currents. The purpose of the invention is to reduce power consumption and simplify manufacturing technology. The goal is achieved by the fact that in the heat release the heater is made in the form of a plate element with slots covering the temperature sensitive element and is fixed on one side of it. In addition, in the indirect heat heater, the heater may surround the temperature-sensitive element so that it forms an open circuit around the temperature-sensitive element. FIG. 1 shows one of the possible variants of the proposed indirect heat release; in fig. 2 shows section A-A in FIG. one; in fig. 3 - thermal release of indirect heating with three slots in the heater. The indirect heat-release heater contains a temperature-sensitive element 1 rigidly fixed with one end 2 and acting with the other end 3 on the control mechanism of the device 4, a heater 5 with slots 6 and current leads 7. The heater 5 end 8 is rigidly fixed on the fixed end 2 of the temperature-sensitive element 1. Screw 9 serves to calibrate the thermal release of indirect heating. The heater 5 is connected to the protected circuit by welding and soldering 10 through the current leads 7 (the arrows indicate the direction of the current of the protected circuit in the heater 5). Thermal trip indirect heating works as follows. When the current of the protected circuit passes through the heater 5, the latter heats up. Since the thermosensitive element 1 is inside the heater 5, it is also heated by convection and heat conduction. When the temperature-sensitive element is heated, the free end 3 bends from one side of the heater to the other. As a result of such bending, the heating temperature of the temperature sensitive element does not change, as far as the heating temperature of the heat sensitive element I decreases from one side of the heater (from which the temperature sensitive element 1 deforms), the same temperature increases from the other side of the heater (facing the deformation of the temperature sensitive element) . The heating temperature of the thermosensitive element 1 is determined only by the temperature of the heater 5, and the temperature of the heater 5, in turn, at the same current value of the protected circuit and its flow time is determined by the electrical resistance of the heater, i.e. 6 increases the current flow path in the heater and reduces its cross section. Thus, with limited dimensions of the heater, it is possible to increase the length of the current flow in the heater and reduce the cross section of this path, which significantly increases the heating of the thermosensitive element. The release switch is calibrated with screw 9. The current of the protected circuit is supplied to the heater by means of current leads 7, connected by welding 10 to the heater. The proposed indirect heat release is primarily intended for perspective series automatic switches of rated current up to 160 A. The release allows heating of the thermosensitive element regardless of the magnitude of its deformation, which entails a decrease in power consumption, an increase in the reliability of operation, and a reduction in the counter force to act reduction of material strength., reduction in the use of critical materials, improvement in the manufacturability of the release. . Claim 1. Thermal release indirect heating, mainly for circuit breakers containing a temperature-sensitive element, rigidly fixed at one end and installed with the possibility of the other end on the control mechanism, and a heater with current leads, in order to reduce power consumption and simplification of manufacturing technology, the heater is made in the form of a plate element with slots covering the temperature-sensitive element, and is fixed with one of its the toryons. 2. The thermal release according to claim 1, characterized in that the heater covers thermosensitive element so that it forms an open circuit around the thermosensitive element. Sources of information taken into account in the examination 1. Author's certificate CC € Р № 281611, cl. H 01 H 71/16, 1967. 2. USSR author's certificate number 469158, cl. H 01 H 61/02, 1975. 3. Automatic switch type ET-225. Catalog of firm UT-E, USA. - / f FIG. g / ff Fug.