JPH05128958A - Current displaying apparatus of circuit breaker - Google Patents

Abstract

PURPOSE:To read flowing current of a circuit breaker without an ammeter. CONSTITUTION:While a bimetal 5 of a thremodynamic over current drawing out apparatus 3 which is built in a circuit breaker is attached to a pointer 10, a window is opened in a cover 2 and a current displaying piece 12 in which current scales are formed is provided and the displacement of the pointer 10 which is curved when electric current flows in a heater 4 is read in the current scales.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker, such as a circuit breaker for wiring, for displaying a current flowing through the circuit breaker.

[0002]

2. Description of the Related Art Conventionally, an ammeter has been used to know the current of a circuit breaker.

[0003]

However, in such a conventional method, it is necessary to install an ammeter separately from the circuit breaker and connect them by wiring, which is expensive and requires a lot of space. Needed. It is an object of the present invention to provide a current display device for a circuit breaker, which is inexpensive and allows current to be read without requiring an installation space.

[0004]

SUMMARY OF THE INVENTION The present invention constitutes a current display device by utilizing a thermal type overcurrent trip device incorporated in a circuit breaker. That is, according to the present invention, in the circuit breaker in which the bimetal is bent by the heat of the heater and tripped when an overload current flows, the pointer is attached to the tip of the bimetal while the pointer is visible on the main body cover of the circuit breaker. It is assumed that a transparent portion is formed and a current indicating piece having a current scale along the curved direction of the bimetal is attached to the transparent portion.

In that case, a current correction piece having a temperature scale indicating the ambient temperature of the bimetal is provided next to the current display piece,
If the position of the current indicating piece with respect to the pointer of the bimetal can be adjusted according to the ambient temperature using the temperature scale, the reading error due to the ambient temperature of the bimetal can be easily corrected. Further, if a lens for enlarging the scale of the pointer, the current display piece and the current correction piece is formed on the transparent portion of the main body cover, the reading of the scale becomes easy.

[0006]

In the circuit breaker having the built-in thermal overcurrent trip device, the current passing through the circuit breaker flows through the heater to which the bimetal is fixed, and the bimetal is heated by the resistance of the heater and bent. Since this bending amount changes according to the electric current, the displacement of the pointer at the tip of the bimetal is read as the electric current value on the electric current scale of the electric current indicating piece mounted on the transparent portion of the main body cover.

[0007]

1 and 2 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of an essential part of a circuit breaker, and FIG. 2 is II of FIG.
It is a principal part enlarged plan view which follows the II line. In these figures, 1 is a case of molded resin, 2 is a cover,
A thermal type overcurrent trip device 3 is provided on the illustrated load side of the case 1.
Is provided. The overcurrent trip device 3 is composed of a heater 4 and a bimetal 5. The base end of the bimetal 5 is fixed to the heater 4 with a rivet 6 and the tip reaches near the cover 2. The heater 4 has a lower end portion connected to a movable contact (not shown) via a connection conductor (not shown), and an upper end portion connected to a load side terminal plate 7.

An adjusting screw 8 is screwed into the upper end of the bimetal 5 and fixed by a nut 9, and a pointer 10 is sandwiched between the nut 9 and the bimetal 5 by utilizing these. Then, a window is opened right above the cover 2 so that the pointer 10 can be seen, and a transparent cover 11 which is entirely formed as a convex lens is attached. Below the transparent cover 11, a current display piece 12 is mounted using a groove (not shown) of the cover 2 so as to be movable in the left-right direction in FIG.
An operation knob 12a is formed at one end thereof so as to rise toward the surface of the cover 2. A current correction piece 13 (FIG. 2) is fixed next to the current display piece 12.

As shown in FIG. 2, a current scale is provided on the pointer 10 side of the current indicating piece 12 along the curving direction of the bimetal 5, that is, the horizontal direction of FIG. 1 (the vertical direction of FIG. 2), and vice versa. A correction mark 12b is attached to the side. Further, the current correction piece 13 is provided with a temperature scale in the same direction as the current scale. Since the transparent cover 11 is a convex lens as described above, the pointer 10, the current display piece 12, and the current correction piece 13 are enlarged and seen through this.

Now, when the circuit breaker is turned on, a current flows through the heater 4, and the heater 4 generates heat due to resistance to heat the bimetal 5. The heated bimetal 5 is curved and the tip portion is displaced leftward in FIG. Since this displacement increases with the magnitude of the current, a current scale that is calibrated in advance so as to increase in the direction of increasing displacement is provided as shown in FIG. 2, and if this scale is read by the pointer 10, the current at that time is read. I understand.

The amount of bending of the bimetal 5 is affected by the ambient temperature, and even if the current is the same, the amount of bending increases as the ambient temperature rises. Therefore, the current correction piece 13 is provided,
The current display piece 12 is moved by gripping the operation knob 12a, and the correction mark 12b is set on the temperature scale according to the ambient temperature at that time. As a result, for example, when the ambient temperature rises, the position of the current display piece 12 is adjusted in the bending direction of the bimetal 5, and accordingly, the reading of the current scale becomes smaller and the apparent increase of the current is corrected. When the current flowing through the heater 4 becomes overloaded, the adjusting screw 8 causes the tripping mechanism 1 to move.
4 (FIG. 1) is pressed to release the lock of the opening / closing mechanism (not shown) to open the circuit breaker.

[0012]

As described above, according to the present invention, the simple construction in which the pointer is attached to the bimetal and the current is read from the displacement thereof eliminates the need to connect an ammeter to the outside of the circuit breaker and is inexpensive. Space-saving current display is possible.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part of a circuit breaker showing an embodiment of the present invention.

FIG. 2 is an enlarged plan view of an essential part taken along the line II-II of FIG.

[Explanation of symbols]

 1 Case 2 Cover 3 Overcurrent trip device 4 Heater 5 Bimetal 10 Pointer 11 Transparent cover 12 Current display piece 13 Current correction piece

Claims (3)

[Claims] 1. A circuit breaker in which a bimetal is bent and tripped by heat of a heater when an overload current flows,
While the pointer was attached to the tip of the bimetal, a transparent portion where the pointer was visible was formed on the cover of the circuit breaker, and a current indicator piece having a current scale along the curved direction of the bimetal was attached to this transparent portion. A current display device for a circuit breaker characterized by the above. 2. A current correction piece having a temperature scale indicating the ambient temperature of the bimetal is provided next to the current display piece, and the position of the current display piece with respect to the pointer of the bimetal is adjusted according to the ambient temperature using the temperature scale. 2. The circuit breaker current display device according to claim 1, wherein the current display device is adjustable. 3. The current display device for a circuit breaker according to claim 1, wherein a pointer, a current display piece and a lens for enlarging the current correction piece are formed on the transparent portion of the cover.