JPS61167873A - Shield resistance voltage divider - Google Patents

Abstract

PURPOSE:To suppress high-frequency oscillation and to measure an impulse voltage with a sharp waveform without any distortion by providing a shield ring, damping resistor, voltage dividing resistor, etc. CONSTITUTION:The voltage dividing resistor 11 has distributed electrostatic capacity. The shield ring 9 has ground electrostatic capacitor CS and also has coupling electrostatic capacity CC to a voltage application terminal 12 and distributed electrostatic capacity Csg to the resistor 11. Then, the size of the terminal 12 is reduced to reduce the electrostatic capacity CC, and the damping resistor 10 is provided to suppress efficiently the high-frequency oscillation based upon the inductance LS of an application wire 22 and the resonance of the electrostatic capacity CS of the ring 9. The earth potential of the ring 9 is made lower than the terminal voltage across the resistor 11 by the resistor 10 and a charging current which flows to the ground is generated. Accordingly, the size and position of the ring 9 are determined so that the earth distributed electrostatic capacity of the resistor 11 is uniform at respective parts, thereby shortening a response time.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention is used to measure high-voltage pulse voltages such as lightning impulse voltages and cutting wave voltages whose waveforms have sharp rises and falls. Concerning the structure of a shielded resistor voltage divider.

[Prior art and its problems]

In this type of voltage divider, in order to divide high voltage pulses of several tens of thousand CV into voltages of several hundred volts or less suitable for waveform observation, an insulating structure that can withstand high voltages and a high High frequency response characteristics are required.

FIG. 3 is a principle explanatory diagram of a conventional resistance voltage divider. A voltage dividing resistor 11 supported vertically on the ground is grounded at its lower end, has a voltage application terminal 12 at its upper end, and has a voltage application terminal 12 at its lower end. A measurement terminal 13 is provided near the section, and the applied voltage V (t,)
The measured voltage V! is based on a predetermined resistor voltage division ratio. (t) It is configured to divide the voltage into K and output it to the measurement circuit connected to the measurement terminal 13.

However, the voltage dividing resistor 11 has a unit height ds with respect to the ground.
At 1) Each part of the voltage dividing resistor 11 has a distributed capacitance to ground of Ct・da, and its value is large on the measurement terminal 13 side, and small on the voltage application terminal 12 side, with an unequal distribution. The high frequency response characteristics deteriorate due to the charging current flowing from Cf・dg to the ground side, and even when a right-angle wave V(t) is applied, a voltage Vd(t)L with a blunted wavefront is observed on the measurement terminal 13 side. The problem is that it cannot be done.

Figure 4 is an explanatory diagram of the principle of a conventional shielded resistor voltage divider. In Figure 6, which shows an example of a self-supporting shielded resistor voltage divider, the voltage dividing resistor 11 is a cylindrical insulating container. 1, the insulating container 1 is vertically supported by a stand 2, and a large head fitting 3' equipped with a voltage application terminal 12 is provided at the upper end of the umbilicus. Metal j protrudes radially from the metal fitting 3! The shield link 5 is supported substantially concentrically with the insulating container 1 via a support arm 14 made of a metal. In the shield resistance voltage divider configured as described above, a distributed capacitance Ca-dz is formed between the shield link 5 and the voltage dividing resistor 11, and the voltage dividing resistor 11 is connected to the voltage dividing resistor 11 via CM@d#. Due to the charging current supplied to the ground distribution capacitance C in Figure 3,
The current is compensated for the charge flowing to the ground via f・ds, and the potential distribution near the voltage dividing resistor 11 is made into a quasi-equal electric field due to the charging current flowing via the ground capacitance C1 of the shield ring 50. As a result, the influence of the ground distributed capacitance Cf·da on the voltage dividing resistor 11 is reduced, and the high frequency response characteristics of the voltage divider can be improved. However, when connecting the shielded resistance voltage divider to the impulse voltage generator 21 through the entire application line 22 and measuring the impulse voltage generated by the generator 210, the inductance L# of the application line 22 and the shield ring 50 relative to the ground Capacity C
8 and the impulse voltage generator 21, a problem arises in that a high frequency oscillating voltage is superimposed on the measurement impulse voltage waveform output from the measurement terminal 13, which impedes observation of the voltage waveform. There is.

[Purpose of the invention]

The present invention was devised in view of the above-mentioned situation, and an object of the present invention is to provide a shielded resistance voltage divider that suppresses high-frequency vibrations and can measure impulse voltages with steep waveforms without distortion.

[Key points of the invention]

The present invention provides a small voltage application terminal conductively connected to the voltage dividing resistor at approximately the center of an upper cover plate made of an insulating material of a cylindrical insulating container housing a voltage dividing resistor, A cylindrical insulating arm projecting radially from the upper end portion supports the lead link in an almost concentric manner insulatingly in the insulating container. In addition to the structure in which a braking resistor is conductively connected to the shield ring, the braking resistor is inserted between the inductance of the application line and the ground capacitance of the shield ring, and the voltage application terminal is miniaturized. By reducing the parallel static capacitance of the braking resistor, high frequency vibrations of the applied voltage can be effectively suppressed.

[Embodiments of the invention]

The present invention will be explained below based on one embodiment.

FIG. 1 is a schematic side sectional view showing an embodiment of the shielded resistance voltage divider of the present invention. In FIG. It is fixed to the pedestal 2 and supported vertically, and its upper end is closed by a cover plate 6VC made of an insulating material and provided with a voltage application terminal 12 in the center. 11 is a non-inductive wire-wound resistor housed approximately in the center of the insulating container 1;
It is a voltage dividing resistor made of a carbon film resistor, etc., and its upper end is conductively connected to the voltage application terminal 12, and its lower end is conductively connected to the ground terminal 14, and is connected to the high voltage side 11A and the detection side so as to obtain a predetermined voltage division ratio. When a predetermined position A of the resistor divided into 11BK is conductively connected to the measurement terminal 13, the main body of a resistance voltage divider is formed. Reference numeral 7 designates cylindrical insulating arms that protrude radially from near the upper end of the insulating container 1. The tips of the plurality of insulating arms are connected to the shield link 9, and the shield link 9 is attached to the insulating container 1 approximately. Concentric Kl! ! ! Configured for edge support. 7Fi A braking resistor housed in one insulating arm 71, -
One end is connected to the voltage application terminal 12, and the other end is connected to the shield ring 9.
are conductively connected to each other.

FIG. 2 is a connection diagram for explaining the function of the shielded resistance voltage divider shown in FIG. 1, and also shows the stray capacitance of each part as a lumped constant.

In the figure, reference numeral 21 denotes an impulse voltage generator, which is connected to the voltage application terminal 12 through an application 11122, and whose measurement terminal side is connected to a waveform observation device 24 via a measurement cable 23 equipped with a matching resistor. In the impulse voltage measuring circuit configured in this way, the voltage dividing resistor 11 has the distributed capacitance Cy@(lt
x, the total resistance value of the resistor 11 is Ri, and the total distributed capacitance is Ct, then the square wave response time T is T=
It has a characteristic as expressed by -fRf-Cf.

On the other hand, the shield link 9 supported by the insulating arm 7 and conductively connected to the voltage application terminal via the braking resistor 10 has a ground capacitance Cm, and has a coupling capacitance container Ca and a voltage dividing resistor to the voltage application terminal. The capacitance has a distributed capacitance of 11.

゛ In the above-mentioned embodiment, the head fitting 3 and the support arm 4 of the conventional shield voltage divider shown in FIG.
By eliminating large high-voltage charging parts such as the voltage application terminal 12,
By making it small, it is possible to significantly reduce the coupling capacitance CC1 between the voltage application terminal portion including the voltage application terminal 12 and the shield link 9, in other words, the parallel capacitance of the braking resistor 10. Therefore, number 10 to number 1
By providing the braking resistor 10 with a resistance value of approximately 00Ω, high frequency vibrations due to resonance of the inductance Lm of the application line 22 and the ground capacitance C# of the shield ring 9 can be efficiently suppressed.

On the other hand, by providing the braking resistor 10, the potential of the shield ring 90 to the ground becomes lower than the potential of the voltage application terminal 120 to the ground, that is, the voltage between the terminals of the voltage dividing resistor 11. Based on this potential difference, the voltage dividing resistor 11 from distributed capacitance C1t
A charging current is generated that flows to the ground side via the ground capacitance C# of the shield ring 90. The magnitude of this charging current flows distributed in the height direction of the voltage dividing resistor so that it becomes larger as it approaches the voltage application terminal 12, and the charging current flows through the ground distributed capacitance Cp@dm of the voltage dividing resistor 110. The distribution is the opposite. Therefore, by utilizing the complementary effect between the distribution of r4 and the distribution of Caf, the distributed capacitance to ground of the voltage dividing resistor 11 is expressed equally in each part. By determining the size or position of the shield link 9 in such a manner, a shield resistance voltage divider with a short response time can be formed.

Although the above-described embodiments have been explained using a free-standing shielded resistance voltage divider as an example, it is clear that the same function can be obtained by using a suspended type.

〔Effect of the invention〕

As described above, the present invention includes a main body of a resistive voltage divider housed in a vertically supported cylindrical insulating container, and an insulating arm supported by cylindrical insulating arms projecting radially from the top of the insulating container. The shield ring is electrically conductively connected to a voltage application terminal formed in a small size through a braking resistor housed in the brake resistor. As a result, the coupling capacitance between the voltage application end and the shield ring, in other words, the parallel capacitance of the braking resistor, can be reduced, and the inductance of the voltage application line and the ground static capacitance of the shield ring, which were problems in the past, can be reduced. It is possible to provide a shielded resistance voltage divider that eliminates high-frequency vibrations due to resonance with the capacitance and can measure steep waveform innocuous voltages without distortion.

[Brief explanation of drawings]

Fig. 1 is a schematic side sectional view showing an embodiment of the present invention, Fig. 2 is a connection diagram for explaining the function of the embodiment shown in Fig. 1, and Fig. 3 shows the principle of a conventional resistive voltage divider. The explanatory diagram, FIG. 4, is a diagram illustrating the principle of a conventional shielded resistance voltage divider. 1... Insulating container, 2... Frame, 3... Head metal fitting,
4...Support arm, 5.9...Shield ring, 6
... Lid plate, 7... Insulating arm, 10... Braking resistor, 11... Voltage dividing resistor, 12... Voltage application terminal,
13...Measurement terminal, 22...Applying line, Of...Distributed ground capacitance of the voltage dividing resistor, Ca...ground capacitance of the shield ring, La...Inductance of the applying line, co...parallel capacitance of braking resistor.

Claims (1)

[Claims] 1) A cylindrical insulating container that is vertically supported and has a small voltage application terminal approximately in the center of an upper cover plate made of an insulating material, and a cylindrical insulating container that is housed approximately concentrically within this insulating container and has the voltage application terminal at its upper end. a plurality of cylindrical insulating arms projecting radially from near the upper end of the insulating container, and a shield supported substantially coaxially with the insulating container by the insulating arms. A shielded resistance voltage divider comprising: a ring; and a braking resistor housed in the insulating arm and having both ends conductively connected to the voltage application terminal of the voltage dividing resistor and the shield ring.