JPH0643186A - Current shunt - Google Patents

Abstract

PURPOSE:To achieve a current shunt which can protect components connected to a current channel when eddy current flows, with a relatively simple configuration. CONSTITUTION:The shunt consists of a shunt connected to a current channel in series, a temperature sensor 2 for measuring the surface temperature of the shunt, a switch 3 connected to the shunt 2 in parallel, and a switch control element 4 for closing and opening the switch 3 when the temperature detection signal of the temperature sensor 2 is higher and lower than a setting temperature, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current shunt device, and more particularly, to overcurrent protection of a shunt used in a current measuring device or a current measuring instrument.

[0002]

2. Description of the Related Art Conventionally, generally, when measuring current,
BACKGROUND ART A shunt is connected in series to a current path, and the voltage across the shunt is measured by an analog or digital voltage measuring device. By the way, in the current measurement with such a configuration, if an overcurrent exceeding the rated value flows in the shunt, the shunt will overheat and the equipment around the shunt will burn out, or the shunt itself will burn out. It may become impossible to measure.

Therefore, as a countermeasure against such an overcurrent, for example, a fuse or a breaker is connected in series with a shunt, and if an overcurrent flows, the fuse is blown or the breaker is operated to interrupt (open) the current path. Is being done.

[0004]

However, according to such a structure, once the overcurrent flows and the current path is opened, in order to close the current path again, the fuse is replaced or the breaker is reset. Although it must be done, there are many cases where it is extremely dangerous for the operator to get an electric shock when working while forgetting that the current path is a live line.

Further, when the current path is opened or closed, a large electrical fluctuation is suddenly applied to the components of the current path such as the power source, the load and the measurement system connected to the current path. There is also the risk of secondary damage to the components of the current path. The present invention solves such problems, and an object thereof is a current shunt device having a relatively simple structure and capable of protecting various components connected to a current path when an overcurrent flows. Is to realize.

[0006]

In order to solve such problems, the present invention provides a shunt connected in series with a current path, a temperature sensor for measuring the surface temperature of the shunt, and a shunt. And a switch control element that controls to close the switch when the temperature detection signal of the temperature sensor becomes higher than the set temperature and open the switch when the temperature detection signal of the temperature sensor becomes lower than the set temperature. Characterize.

[0007]

When the temperature of the shunt becomes higher than the set temperature due to the overcurrent flowing through the shunt, the switch is closed by the control of the switch control element. As a result, a part of the overcurrent flowing through the shunt flows through the switch side, and the overheated state of the shunt is eliminated. Then, when the temperature of the shunt drops below the set temperature, the switch is reopened under the control of the switch control element.

As a result, the switch is automatically opened / closed according to the temperature change of the shunt. Moreover, since the current path itself is not directly opened and closed, it is possible to prevent secondary damage to various components of the current path.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of the principle of the present invention. In the figure, 1
Is a shunt and is connected in series to the current path. A temperature sensor 2 is provided to measure the surface temperature of the shunt 1. A switch 3 is connected in parallel with the shunt 1. Reference numeral 4 denotes a switch control element, which controls to close the switch 3 when the temperature detection signal of the temperature sensor 2 becomes higher than the set temperature and to open the switch 3 when the temperature detection signal becomes lower than the set temperature.

To embody such a principle circuit, various configurations such as a method using an electric circuit, a method using mechanical elements, and combinations thereof can be considered.
FIG. 2 is a specific example of FIG. 1 and shows an example in which only mechanical elements are used, and the same parts as those in FIG. In FIG. 1, an insulator 5 having excellent thermal conductivity is attached to the surface of the flow distributor 1. A bimetal used as the temperature sensor 2 is arranged in the vicinity of the upper portion of the insulator 5 along the longitudinal direction. That is, one end of the bimetal 2 is fixed to one end of a frame 6 made of an electrical conductor, and the other end of the bimetal 2 has a movable contact 3a that constitutes a switch 3.
Is attached. The other end of the frame 6 is electrically connected to a current path on one end side of the shunt 1 and is mechanically fixed. A frame 7 made of an electric conductor is electrically connected to the current path on the other end side of the shunt 1 and is mechanically fixed. The frame 7 is formed into a substantially L-shape by bending, and a distance between the fixed contact 8 and the movable contact 3a is adjusted via a fixed nut 8 so that the fixed contact 3b constituting the switch 3 faces the movable contact 3a. It is possible to install.

The operation of such a structure will be described. The heat generated by the shunt 1 is conducted to the bimetal 2 via the insulator 5.
The bimetal 2 is deformed in a direction approaching the fixed contact 3b in accordance with a change in the temperature that is conducted, and is deformed by a distance equal to or more than a preset distance, whereby the movable contact 3a and the fixed contact 3 are deformed.
The switch 3 is closed by contact with b. A second current path is formed in parallel with the shunt 1 by closing the switch 3, and a part of the overcurrent flowing through the shunt 1 is shunted to the second current path. In this way, a part of the overcurrent is shunted to the second current path, so that the heat generation of the shunt 1 is alleviated, the temperature conducted to the bimetal 2 is lowered, and the bimetal 2 is automatically restored to the initial state. , Switch 3 is opened again.

Here, the distance between the movable contact 3a and the fixed contact 3b is appropriately adjusted according to the deformation characteristic of the bimetal 2 with respect to the temperature change from the normal state. As a result, it is possible to prevent burning of various components connected to the current path due to the heat generation of the shunt 1, and when the heat generation temperature of the shunt 1 drops to the normal state, the switch 3 automatically returns to the initial state. To do.

With this structure, a power supply for driving is not necessary, and the bimetal 2 is the temperature sensor 2 shown in FIG.
Since it also has the function of the switch control element 4, the structure is simple, the cost can be reduced, and maintenance is unnecessary. Note that, as described above, the configuration having the same function as in FIG. 2 can be configured by an electric circuit. in this case,
Although a power supply is required and the cost is relatively high, an effect that cannot be obtained with the configuration of FIG. 2 such as the responsiveness to temperature can be set freely can be obtained.

[0014]

As described above, according to the present invention,
With a relatively simple structure, it is possible to realize a current shunt device that can protect various components connected to a current path when an overcurrent flows.

[Brief description of drawings]

FIG. 1 is a principle circuit diagram of the present invention.

FIG. 2 is a structural explanatory view showing a specific example of FIG.

[Explanation of symbols]

 1 Shunt 2 Temperature sensor 3 Switch 4 Switch control element 5 Insulator 6,7 Frame 8 Fixing nut

Claims (1)

[Claims] 1. A shunt connected in series to a current path, a temperature sensor for measuring the surface temperature of the shunt, a switch connected in parallel with the shunt, and a temperature detection signal of the temperature sensor that is higher than a set temperature. A current shunt device comprising a switch control element that controls to close the switch when the temperature becomes higher and to open the switch when the temperature becomes lower than the set temperature.