JPS6291862A - Shunting type current detector - Google Patents

Abstract

PURPOSE:To constitute the titled detector so that a resistance element is scarcely influenced by a variation of a flow rate of water in a cooling body, and also to raise the current detecting accuracy by connecting a voltage detecting signal line of the current detector to both ends of the resistance element which is positioned in the vicinity of a refrigerant inlet of the cooling body. CONSTITUTION:Plural pieces of resistance elements 1 are connected in parallel, respectively, between two pieces of internal conductors 5 through its lead wire 6, and the internal conductors 5 are connected to two pieces of main circuit conductors 3, respectively. The resistance element 1 is cooled by a refrigerant (water) flowing through a cooling body having a refrigerant inlet 8 and a refrigerant outlet 9 in one end and the other end, respectively. Also, a voltage detecting signal line 4 is connected across a resistance element 1a which is positioned in the vicinity of the refrigerant inlet 8 of the cooling body 7, so as to fetch a voltage drop in the resistance element 1a as a voltage for detecting a current. In such a way, even if the water flow rate varies, it scarcely affects the change of temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a shunt type current detector in which a plurality of resistance elements are connected in parallel and mounted on a cooling body cooled by a suitable refrigerant. In this type of current detector, especially a high-precision current detector, in order to improve the detection accuracy, the resistance value of the detection resistor consisting of the resistor element is set to energize. It
It is desired that the refrigerant in the cooling body for suppressing the temperature rise of the resistive element is hardly affected by changes in the snow flow and is hardly affected by the power loss due to the flow.

[Prior art and its problems]

What is generally known as a shunt type current detector uses brass or other conductive material as a detection resistor, and current is detected by measuring the voltage drop due to the resistance. Since the resistance temperature coefficient of the detection resistor itself is as high as approximately 2000/C, the detected current value is easily affected by the temperature rise of the resistor, and therefore the detection accuracy cannot be said to be high. Therefore, in order to perform highly accurate current detection, a resistor is made by connecting a large number of so-called high-precision metal foil resistance elements in parallel, which have extremely low resistance temperature coefficients and are manufactured by gluing metal foil to ceramic or glue. A shunt type current detector is used.

In this type of current detector, as illustrated in the M2 diagram,
A plurality of resistive elements 1 are connected via their lead wires 6 between two internal conductors 5 so that they are mutually parallel, and each internal conductor 5 has two internal conductors 1 at its connection terminals 2. It is connected to the main circuit conductor 3 to form a detection circuit, and each resistor element 1 is connected to one end of the refrigerant inlet 8.
A refrigerant outlet 9 is provided at the other end of the refrigerant, and the refrigerant is disposed on a cooling body 7 which is cooled by the refrigerant flowing inside the cooling body 7 so as to be cooled via the cooling body 7. Furthermore, a voltage detection signal line 10 is connected to the connection terminal 2 for detecting the voltage of a detection resistor made up of the plurality of resistance elements 1 and two internal conductors 5.

At this time, the resistive element 1 is cooled via the cooling body 7 as described above in order to increase its allowable power consumption, in other words, to increase the current value flowing through the resistive element 1.
In this case, water is usually used as a refrigerant for the cooling body from the viewpoint of reducing the thermal time constant of the detection resistor and facilitating temperature control.

On the other hand, the resistance temperature coefficient of the resistance element 1 itself used in the current detector can be made extremely small, usually 5 to 110 PP/C, but it may be made of, for example, steel (with a resistance temperature coefficient of approximately 4000 PP). The temperature coefficient of resistance of the internal conductor 5 and the resistance element lead lll6 cannot but be large. Therefore, in order to increase the current flowing through the current detector in order to improve its detection accuracy, the ratio of the resistance value of the resistor element 1 itself to the total resistance value of the current detector must be increased by increasing the resistance value of the internal conductor 5 or the resistor element lead. The current detector as a whole should have a small resistance temperature coefficient by configuring it so that it has a small resistance value compared to the resistance value of the wire 6, and even if the resistance temperature coefficient is somewhat high, the resistance of the resistance element 1 itself is small. Lower the value to 11! : Design the current detector by considering the advantages and disadvantages of reducing the power loss of the fi detector itself, and thus also reducing its temperature rise to make it less affected by the resistance temperature coefficient, and finding a compromise. However, in general, the temperature coefficient of resistance as a current detector has to settle down to about several tens of pp-, and there is a problem that it is difficult to realize a temperature coefficient of resistance even smaller than that. Furthermore, even if the resistance temperature coefficient of the resistance element 1 itself can be reduced, in the conventional current detector, when the flow rate of cooling water in the cooling body 7 changes, the resistance temperature coefficient of the resistance element 1 located near the drain port 9 changes. Temperature changes easily, and its resistance value is large f! I
EI+ causes a detection error as a current detector,
Furthermore, if the internal conductor 5 is not directly cooled with water or the like, the thermal time constant of the resistance in that part becomes large, and the time required for the detection resistance value to stabilize as a current detector becomes long. is accompanied by

[Purpose of the invention]

In view of the above-mentioned drawbacks that the conventional shunt type current detector has in improving its detection accuracy, the present invention provides an extremely simple means in which the resistance element is not easily affected by changes in the flow rate of water in the cooling body, and the current detection accuracy is improved. The purpose of the present invention is to provide a shunt type current detector with higher current.

[Key points of the invention]

In order to achieve the above object, the present invention provides the current detector described above, in which a voltage detection signal line of the current detector is connected to both ends of the resistance element located near the refrigerant inlet of the cooling body. Thereby, a voltage signal for current detection is extracted from a resistance element that has a small resistance temperature coefficient and is not easily affected by changes in the flow rate of the refrigerant in the cooling body.

[Embodiments of the invention]

Next, the present invention will be explained in detail based on embodiments shown in the drawings.

In the shunt type current detector of the present invention illustrated in FIG. 1, a plurality of resistance elements 1 are connected in parallel between two internal conductors 5 via their lead wires 6, and Each of the internal conductors 5 is connected to the two main circuit conductors 3 at its connecting terminal 2 to form a detection circuit, and each of the internal conductors 5 is provided with a refrigerant outlet 8 at one end thereof and a refrigerant outlet 9 at the other end thereof, Similar to the conventional shunt type current detector, the detector is disposed on a cooling body 7 that is cooled by a refrigerant flowing therein, and is cooled via the cooling body 7.

However, in the current detector of the present invention, the voltage detection signal @4, which was connected to the connection terminal 2 of the internal conductor 5 in the conventional current detector, is connected to the refrigerant of the cooling body 7, in this case, at the inlet 8 of the cooling water. The resistor element 1a is connected to both ends of the resistor element 1a located near the resistor element 1a, and the voltage drop across the resistor element 1a is extracted as a voltage for current detection.

In this case, a resistor element is used to increase the Mlf of current detection]
, a, it is preferable to select one having a particularly small resistance temperature coefficient from among the plurality of resistance elements 1 constituting the current detector. As for other resistive elements, for example, if one with a positive temperature coefficient of resistance and one with a negative temperature coefficient are arranged adjacently, then looking at the current detector as a whole, each of the 11 resistive elements will share 1 L. The resistor elements 1 are arranged so that they do not wobble due to temperature changes, and the temperature coefficient of resistance is as small as possible as a parallel circuit of several resistor elements 1 when viewed partially. good.

Furthermore, in this case, it is advantageous to improve the detection accuracy by controlling the temperature of the cooling water for the cooling body 7 before supplying it, and also to stabilize the detection resistance value of the current detector in a short time. It is preferable to similarly cool the internal conductor 5 with water or the like to reduce its thermal time constant.

〔Effect of the invention〕

As described above, the present invention uses a shunt type photodetector in which a plurality of resistive elements are connected in parallel and mounted on a cooling body cooled by an appropriate refrigerant, and detects the voltage of the current detector. By connecting the signal line to both ends of the resistance element located near the refrigerant inlet of the cooling body, the temperature coefficient of resistance of the X-photodetector is almost the same as that of the voltage detection signal line. Since it is the resistance temperature coefficient of the connected resistance element itself, it is a much smaller value than the resistance temperature coefficient when a predisposing factor such as an internal conductor is included in addition to the resistance element as in a conventional tVa detector. Furthermore, since the resistance element is located near the refrigerant inlet of the cooling body, even if the flow rate of the refrigerant changes, the temperature will hardly change due to the effect of the change. This has the effect of significantly improving its detection and placement.

[Brief explanation of drawings]

FIG. 1 shows a schematic circuit configuration of a shunt type accent detector according to the present invention, and FIG. 2 shows a schematic circuit configuration of a conventional shunt type photodetector. 1.1a...Resistance element, 4...Voltage detection signal line. 6°°°Resistance element lead wire, 7...Cooling body, 8...
・Refrigerant population. Figure 1 of Yamaguchi's view of stubborn people

Claims (1)

[Claims] 1) In a shunt type current detector in which a plurality of resistance elements are connected in parallel and mounted on a cooling body cooled by an appropriate refrigerant, the voltage detection signal line of the current detector is connected to the refrigerant of the cooling body. A shunt type current detector, characterized in that it is connected to both ends of the resistive element located near the inlet.