JP5187828B2 - Voltage probe - Google Patents

Description

  The present invention relates to a voltage probe. The voltage probe of the present invention is suitably used for high-voltage high-accuracy measurement.

In a high frequency power source for an electron accelerator, a pulse power source for an excimer laser, and the like, it is important to accurately control the voltage of a high voltage power source used inside.
In order to control the voltage of the high-voltage power supply with high accuracy, a high-voltage probe for measuring the high voltage with high accuracy is required. Since feedback control is performed by the output signal of the high voltage probe, the stability of the high voltage power supply system is ultimately determined by the accuracy of the probe. Making a power supply with stability at 100 ppm or better at high voltage is an important issue not only in accelerators but also in other fields.

  Conventionally, as a high voltage probe, a resistor having a resistance value of 1 G ohm or more is connected to the high voltage side, and the current flowing through this resistor flows through the resistor arranged on the low voltage side, thereby reducing the resistance on the low voltage side. A resistance-division probe has been used to measure the voltage generated in the vessel.

  The problems here are the discharge around the resistor on the high voltage side, the Joule heat generation due to the current flowing through the resistor, the change in resistance value due to this heat generation, and the use of a resistor with a large resistance value It was bad frequency response.

First, as a countermeasure against high voltage discharge, conventionally, SF ₆ gas has been sealed in a high voltage probe. However, since SF ₆ gas has a low heat transfer coefficient, there is a problem that the resistor on the high voltage side rises due to Joule heat generation. Therefore, it has been performed to use a resistor having a small temperature coefficient of resistance value. However, it is not easy to make the temperature coefficient of resistance value 10 ppm / ° C. or less in a resistor having a large resistance value. Even if a resistor having a temperature coefficient of 10 ppm / ° C. is used, if the temperature rise of the resistor exceeds 10 ° C., there is a problem that the rate of change in resistance value exceeds 100 ppm.

  Also, to improve the frequency characteristics of the probe, that is, to measure correctly even for high frequency components, it is sufficient to reduce the resistance value of the voltage division. As a result, there is a problem that the resistor becomes high temperature due to Joule heat generation.

  The present invention has been made in view of such circumstances, and provides a voltage probe capable of highly accurate voltage measurement.

Means for Solving the Problems and Effects of the Invention

  The voltage probe of the present invention includes a measurement terminal, a resistor electrically connected to the measurement terminal and housed in a housing, and an output terminal electrically connected to the resistor, the resistor Is immersed in an insulating liquid phase refrigerant in the housing.

In the present invention, the resistor is immersed in an insulating liquid phase refrigerant in the housing. Since the liquid phase refrigerant generally has an extremely large heat transfer efficiency as compared with the conventional SF ₆ gas, the Joule heat generated by the resistor is quickly removed by the liquid phase refrigerant. Therefore, according to the present invention, it is possible to suppress the temperature rise of the resistor, and therefore it is possible to suppress the fluctuation of the measured value caused by the temperature rise of the resistor.

  In addition, according to the present invention, even if the resistance value of the resistor is lowered, the temperature rise of the resistor can be suppressed. Therefore, according to the present invention, it is possible to use a resistor having a relatively small resistance value, and therefore it is possible to improve frequency characteristics.

In addition, liquid phase refrigerants generally have higher withstand voltage characteristics than conventional SF ₆ gas, so that high voltage corona discharge and spark discharge can be prevented, thus enabling safe and stable measurement. Become. Even if the spark discharge does not reach, a minute corona discharge is mixed as an unnecessary random noise signal in the probe output and the system becomes unstable. Therefore, it is important to prevent the corona discharge.

  As mentioned above, according to this invention, the voltage probe which can perform a highly accurate voltage measurement is provided.

Note that the voltage probe of the present invention is particularly preferably used for applications (high voltage applications) in which the voltage to be measured is 10 kV or higher. This is because in such an application, a large amount of Joule heat is generated in the resistor, and therefore it is particularly necessary to quickly remove the Joule heat.
Hereinafter, various embodiments of the present invention will be exemplified.

  One end is further provided with a conductor rod that is the measurement terminal, the other end of the conductor rod is electrically connected to the resistor, and the housing has a space for housing the conductor rod, and An insulating bushing made of a ceramic material; a first metal ring brazed to the tip of the insulating bushing and brazed or welded to the conductor rod; and a second metal ring brazed to a side surface of the insulating bushing; The body cylinder may be provided with one end brazed or welded to the second metal ring and the other end provided with a flange, and a flange lid fixed to the flange of the body cylinder. In the casing having this configuration, the body cylinder is fixed to the insulating bushing made of a ceramic material via a metal ring by brazing or welding, so that no gap is formed between the insulating bushing and the body cylinder. The leakage of the phase refrigerant is reliably suppressed.

You may further provide the cooling part which cools the said liquid phase refrigerant | coolant. The cooling unit may include a helical cooling pipe disposed inside the housing. In this case, the liquid-phase refrigerant that has received Joule heat from the resistor is efficiently cooled.
The various embodiments illustrated here can be combined with each other.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The contents shown in the drawings and the following description are examples, and the scope of the present invention is not limited to those shown in the drawings and the following description.

  A voltage probe according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2 are a cross-sectional view and an exploded perspective view showing the configuration of the voltage probe of the present embodiment. FIG. 3 is a photograph showing the appearance of an example of the voltage probe of the present embodiment.

1. Configuration of Voltage Probe First, the configuration of the voltage probe 1 of the present embodiment will be described.
The voltage probe 1 of the present embodiment includes a measurement terminal 2, a resistor 5 that is electrically connected to the measurement terminal 2 and accommodated in the housing 3, and an output terminal 7 that is electrically connected to the resistor 5. With. The resistor 5 is immersed in an insulating liquid phase refrigerant 9 in the housing 3.

One end of the conductor rod 11 is the measurement terminal 2, and the other end of the conductor rod 11 is electrically connected to the resistor 5.
The housing 3 has a space for accommodating the conductor rod 11 and is made of an insulating bushing 13 made of a ceramic material (eg, alumina ceramic) and brazed to the tip of the insulating bushing 13 and brazed to the conductor rod 11 or A welded first metal ring 15, a second metal ring 17 brazed to the side surface of the insulating bushing 13, one end brazed or welded to the second metal ring 17, and a flange 19 provided at the other end A body cylinder (for example, made of stainless steel) 21 and a flange lid 23 fixed to the flange 19 of the body cylinder 21 are provided. In the casing 3 having this configuration, the body cylinder 21 is fixed to the insulating bushing 13 made of a ceramic material via a metal ring by brazing or welding, so that the space between the insulating bushing 13 and the body cylinder 21 is fixed. Leakage of the liquid phase refrigerant 9 is prevented.

  The material of the first and second metal rings 15 and 17 is not particularly limited, but a metal whose thermal expansion coefficient matches that of the ceramic material of the insulating bushing 13 is preferable, for example, Kovar or molybdenum.

  The flange lid 23 is fixed to the flange 19 with bolts 24 with a gasket (eg, copper gasket) sandwiched between the flange 19 and the flange lid 23. Thereby, the space between the flange 19 and the flange lid 23 is vacuum-sealed. The vacuum sealing between the flange 19 and the flange lid 23 may be performed by using a vacuum sealing member other than a gasket, or may be performed by brazing or welding the flange 19 and the flange lid 23.

  First and second socket electrodes 25 and 27 are disposed at both ends of the resistor 5, respectively. The first socket electrode 25 is screwed to the conductor rod 11.

  A conductive base plate 35 is attached to the flange lid 23 via an output terminal 7 and an insulating support 33. In one example, the output terminal 7 is a vacuum-tight coaxial terminal. The output terminal 7 and the conductive base plate 35 are electrically connected via a signal output line 37. The resistor 5 is electrically connected to the conductive base plate 35 via the second socket electrode 27 (or directly).

The type of the liquid-phase refrigerant 9 is not particularly limited, but is, for example, a fluorinated liquid, insulating oil, silicon oil, or ultrapure water, and a fluorinated liquid is preferable from the viewpoint of withstand voltage characteristics and thermal conductivity. Examples of the fluorinated liquid include Fluorinert and Novec HFE (both manufactured by Sumitomo 3M Limited). Novec HFE is shown in Table 1. It consists of hydrofluoroether.

  By the way, the fluorinated liquid is very easily leaked, and in the conventional configuration in which the space between the bushing and the body cylinder is sealed with the O-ring, the fluorinated liquid leaks from the O-ring. Therefore, when the liquid-phase refrigerant 9 is made of a fluorine-based liquid, the merit of employing the casing 3 having a configuration in which the bushing 13 and the body cylinder 21 are sealed by brazing or welding as in the present invention is particularly advantageous. large.

  The liquid phase refrigerant 9 is cooled by the cooling unit. The configuration of the cooling unit is not particularly limited. In an example, the cooling unit includes a spiral cooling pipe (eg, copper, 4 mm in diameter) 39 disposed inside the housing 3. Two cooling pipe introducing portions 41 are provided on the side surface of the body cylinder 21 (for convenience of illustration, only one is shown in FIGS. 1 and 2). The cooling pipe introduction part 41 is comprised by the member which can hold | maintain the vacuum airtight in the housing | casing 3, and is comprised by a swage lock tube coupling in an example. Both ends of the cooling pipe 39 are connected to two cooling pipe introduction portions 41, respectively, and cooling water introduced from one of the cooling pipe introduction portions 41 is discharged from the other of the cooling pipe introduction portions 41. With such a configuration, the liquid-phase refrigerant 9 that has received Joule heat from the resistor 5 can be efficiently cooled. The cooling water is preferably kept at a constant temperature by temperature control. Thereby, the temperature fluctuation of the liquid phase refrigerant 9 is suppressed. The cooling pipe 39 may be wound around the outside of the body cylinder 21. Moreover, the structure which affixed the Peltier device with the air cooling fan on the fuselage | cylindrical cylinder 21 may be sufficient as a cooling part.

  The body cylinder 21 is also provided with a probe mounting flange 43 and an inspection port 45. The probe mounting flange 43 has a bolt hole 44 and is used for fixing the voltage probe 1. The inspection port 45 is used for confirming the liquid level of the liquid-phase refrigerant 9. The inspection port 45 has a glass window 46 that can be opened and closed. During normal use of the voltage probe 1, the glass window 46 is closed to make the inside of the housing 3 vacuum-tight. The liquid phase refrigerant 9 is injected into the body 3.

2. Method for Manufacturing Voltage Probe Next, a method for manufacturing the voltage probe 1 of the present embodiment will be described. The following method is an example, and the voltage probe 1 of the present embodiment may be formed by another method.

  First, the first metal ring 15 and the second metal ring 17 are brazed to the insulating bushing 13. Next, the center conductor 11 is inserted into the insulating bushing 13, and the center conductor 11 is welded or brazed to the first metal ring 15 in this state.

  Next, the flange 19, the cooling pipe 39, the cooling pipe introducing portion 41, the probe mounting flange 43, and the inspection port 45 are welded or brazed to the body cylinder 21.

  Next, the body cylinder 21 is welded or brazed to the second metal ring 17. As a result, the insulating bushing 13 and the body cylinder 21 are vacuum-sealed.

  Next, the first socket electrode 25 is screwed to the central conductor 11.

  Next, the base plate 35 is fixed to the flange lid 23 via the insulating rod 33, and the second socket electrode 27 is connected to the base plate 35. Further, the output terminal 7 is fixed to the flange lid 23, and the base plate 35 and the output terminal 7 are electrically connected by the signal output line 37.

  Next, one end of the resistor 5 is inserted into the second socket electrode 27, and the other end of the resistor 5 is inserted into the first socket electrode 25 of the body cylinder 21. Next, the flange 19 and the flange lid 23 are fastened with bolts 24 with the gasket sandwiched therebetween, and vacuum sealed. As a result, a vacuum-tight casing 3 is formed.

  Next, the glass window 46 of the inspection port 45 is opened, the liquid refrigerant 9 is injected into the housing 3, the glass window 46 is closed again, and the manufacture of the voltage probe 1 of this embodiment is completed.

3. Next, a method of using the voltage probe 1 of the present embodiment will be described.
The voltage probe 1 is normally used in a state where a resistor 47 is disposed between the output terminal 7 and GND. If the resistance value of the resistor 5 on the high voltage side is R ₁ and the resistance value of the resistor 47 on the low voltage side is R ₂ , the input voltage V ₁ input from the measurement terminal 2 and the output output from the output terminal 7 The following relationship holds between the voltage V ₂ .
V ₂ = V ₁ · {R ₂ / (R ₁ + R ₂ )}

According to the present embodiment, fluctuations in the resistance value R ₁ of the resistor 5 due to heat generation are suppressed, and therefore fluctuations in the output voltage V ₂ are also suppressed, enabling highly accurate voltage measurement. Note that the resistor 47 on the low voltage side may be disposed in the housing 3. In this case, the voltage probe 1 is provided with a GND terminal, one end of the resistor 47 is connected to the output terminal 7, and the other end of the resistor 47 is connected to the GND terminal.

  Moreover, it is preferable to use the voltage probe 1 in the state where the measurement terminal 2 faces downward (the state where the high voltage side faces downward). In this case, air bubbles remaining in the liquid phase refrigerant 9 accumulate in the upper part of the housing 3, and the high voltage side can be completely filled with the liquid phase refrigerant 9. The liquid level of the liquid phase refrigerant 9 can be confirmed through the inspection port 45.

  Further, the entire housing 3 may be filled with the liquid refrigerant 9 without leaving an atmospheric part inside the housing 3. In this case, since no bubbles remain in the housing 3, the voltage probe 1 can be used in any orientation. However, in consideration of the thermal expansion of the liquid-phase refrigerant 9 as the temperature rises, it is desirable to provide an expansion section using a vacuum bellows as appropriate.

  Moreover, it is preferable that the operating temperature of the voltage probe 1 (temperature of the liquid phase refrigerant 9 at the time of use) is a temperature close to room temperature (20 to 30 ° C.). In this case, the influence of the inflow of heat from the body cylinder 21 is small. In addition, it is important to avoid the danger of an increase in internal pressure and explosion due to boiling by making the operating temperature of the voltage probe 1 sufficiently lower than the boiling point of the liquid-phase refrigerant 9.

It is sectional drawing which shows the structure of the voltage probe of one Embodiment of this invention. It is a disassembled perspective view which shows the structure of the voltage probe of one Embodiment of this invention. It is a photograph which shows the external appearance of an example of the voltage probe of one Embodiment of this invention.

Explanation of symbols

1: Voltage probe 2: Measurement terminal 3: Housing 5: Resistor 7: Output terminal 9: Liquid phase refrigerant 11: Conductor rod 13: Insulating bushing 15: First metal ring 17: Second metal ring 19: Flange 21 : Fuselage cylinder 23: flange lid 24: bolt 25: first socket electrode 27: second socket electrode 33: insulation support 35: conductive base plate 37: signal output line 39: cooling pipe 41: cooling pipe introduction part 43: for probe mounting Flange 44: Bolt hole 45: Inspection port 46: Glass window 47: Resistor

Claims (3)

A measurement terminal; a resistor electrically connected to the measurement terminal and housed in a housing; and an output terminal electrically connected to the resistor;
The resistor has a relatively low resistance value in order to improve the frequency response, and removes Joule heat generated by applying a high voltage in the housing and mixing a random noise signal into the probe output by a minute corona discharge. In order to prevent , a conductor rod that is immersed in an insulating liquid-phase refrigerant and has one end as the measurement terminal is further provided, and the other end of the conductor rod is electrically connected to the resistor, and the housing An insulating bushing having a space for accommodating the conductive rod and made of a ceramic material, a first metal ring brazed to the tip of the insulating bushing and brazed or welded to the conductive rod, A second metal ring brazed to a side surface of the insulating bushing; a body cylinder brazed or welded to one end of the second metal ring and provided with a flange at the other end; Voltage probe and a flange cover fixed to the flange of the cylinder. Cooling that cools the liquid-phase refrigerant in order to suppress the temperature rise of the resistor due to Joule heat generated in the resistor, and thus to suppress fluctuations in the measured value caused by the temperature rise of the resistor. The probe according to claim 1, further comprising a portion. The probe according to claim 2 , wherein the cooling unit includes a spiral cooling pipe disposed inside the housing.