JPS60194370A - Voltmeter - Google Patents

Abstract

PURPOSE:To simply perform the correction of a voltmeter utilizing an electrooptical element, by obtaining reference zero level potential in response with the control light signal from the outside. CONSTITUTION:Voltage Vx to be measured is applied between input terminals (a), (b) of a sensor part 1 to be applied to the voltage terminal of a Pockel's element P. When voltage Vx is applied to the element P, light d1 passing through the element P through an input fiber 2 is modulated and because the modulation degree thereof changes corresponding to the magnitude of the voltage Vx, light d2 outputted through an output fiber 3 is detected by a main body part 5 to calculate the voltage value Vx of a measuring object. In performing correction when the voltage Vx is a zero level, a light pulse d3 is applied to a solar cell E through a control fiber 4 and FETQ is turned ON. At this time, the electric terminal of the element P is shortcircuited and voltage at both terminals come to zero to enable correction.

Description

[Detailed Description of the Invention] [Technical field to which the invention pertains] The present invention includes an electro-optic effect element capable of inputting and outputting light through an optical fiber and modulating the output light by an electro-optic effect. The present invention relates to a voltmeter that applies a voltage to be measured between the electrical terminals of an electro-optic effect element and measures the voltage to be measured through output light that is modulated thereby.

[Background of the invention]

There is a voltmeter that indirectly measures the voltage value by first converting the voltage to be measured into an optical signal and measuring this light.

For this purpose, electro-optic effect elements are used as elements that convert voltage values into optical signals. As this electro-optic effect element, for example, Pockels (Poc
keIs) elements are known. The refractive index of the Pockels element changes depending on the applied voltage, and this property is used to perform various modulations (for example,
Amplitude modulation, phase modulation, frequency modulation, polarization plane modulation, etc.) can be performed. In terms of amplitude modulation, the light passing through the Pockels element has a characteristic that it is modulated with an amplitude between O and the maximum incident light depending on the applied voltage.

Generally, in a meter such as the voltage t1, a zero level voltage, which is a reference for the measurement voltage, is calibrated as appropriate to ensure the accuracy of the measured value.

That is, since the deviation from this zero level is the value of the measured voltage, if the zero level is not certain due to the offset of the measuring circuit, the temperature coefficient of the element, etc., accurate voltage measurement cannot be performed. Therefore, a circuit that applies a zero-level voltage to the electrical terminal of the electro-optic effect element is required.

On the other hand, one of the features of devices using electro-optic effect elements is that they use light as a signal medium, so unlike conventional electrical devices, they can separate signals (for example, input signals and output signals) into two signals (for example, input signals and output signals). can be electrically insulated, and in principle there is no influence of electrostatic induction, electromagnetic induction, etc. in the optical signal line section.

CObject of the present invention] An object of the present invention is to provide a voltmeter that can apply a zero voltage level to an electro-optic effect element with a simple circuit while retaining the features of the device using the electro-optic effect element described above. It's about doing.

[Summary of the invention]

The present invention includes an electro-optic effect element capable of inputting and outputting light through an optical fiber and modulating the output light using an electro-optic effect, and applies a voltage to be measured between electrical terminals of the electro-optic effect element. In addition, in a device configured to measure the voltage of the measurement target via the modulated output light, the device is provided between the electrical terminals of the electro-optic effect element and is synchronized with a control optical signal applied from the outside. The voltage g1 is characterized in that it includes a circuit that becomes short-circuited by controlling the optical signal, and is capable of applying a zero-level potential between the electrical terminals of the electro-optic effect element.

an element that is provided between the electrical terminals of the electro-optic effect element and is brought into a short-circuited state via an optical signal, and applies a zero-level potential between the electrical terminals of the electro-optic effect element via the optical signal. It is a voltage tear characterized by = L' so that it can be done.

[Explanation based on examples]

The present invention will be described in detail below using the drawings.

FIG. 1 is a diagram showing an example of the configuration of a voltmeter according to the present invention. In the figure, 1 is a sensor section, and input terminals a,
A voltage Vx to be measured is applied to the voltage Vx to be measured, and this negative voltage Vx is converted into an appropriate signal and sent to the next stage. The present invention is a voltmeter having a feature in this sensor section 1. 2 is an input fiber, 3 is an output fiber, and 4 is a control fiber, all of which are composed of optical fibers. Reference numeral 5 denotes a main unit of voltage y1, which transmits an optical signal to the sensor unit 1 and receives (i) from the sensor unit 1 based on the optical signal.
It has a function of obtaining a value corresponding to the voltage Vx to be measured.

The feature of the present invention lies in the sensor section 1, and for the main body section 5, conventionally known means are used. Therefore, the present invention will be explained by specifically showing the configuration of only this sensor section 1 in FIG. 2.

1. - By the way, Figure 2 is a diagram showing an example of the configuration of the sensor unit 1. In the same figure, 2,3°4 is
This is an optical fiber that performs the same function as the one with the same element number in FIG. The connection destination of each of these optical fibers is the main body portion 5 shown in FIG. Reference numeral 10 denotes an input surge protection circuit, which protects an electro-optical effect element, etc., which will be described later, from being damaged when an abnormally high voltage or the like occurs between measurement terminals a and b. To describe an example of the configuration of this input surge protection circuit 10, resistors R1 and R2 are inserted into the input lines, and a nonlinear element (for example,
It is like connecting a Zener diode. P
is an electro-optic effect element, such as a Pockels element. In the Suimei S+ book, in order to explain the invention in an easy-to-understand manner, the following explanation will be given using an example in which a Pockels element is used as the electro-optic effect element P. Note that the Pockels element has been explained above, so a re-explanation of its functions and the like will be omitted.

12 is a zero potential generation circuit, which is a circuit for applying a zero level voltage to the electric terminal of the Pockels element P. The feature of the present invention is that such a circuit is provided. Describing an example of the configuration of this zero potential generation circuit 12, the switching element Q<
For example, transistors, field effect type transistors, etc.)
is provided between the electrical terminals of the Pockels element P, and an element E having a function of being driven by optical means (for example,
(solar cell, etc.) is connected to the switching element Q, and this element E
The configuration includes a control fiber 4 that applies an optical signal to drive the . In addition, in order to make the invention easier to understand,
A field effect transistor (FET) is used as the switch element Q.
), the following explanation will be given using an example in which a solar cell is used as the element E.

The operation of the voltage screen 1 according to the present invention shown in FIG. 2 and constructed as described above is as follows.

A voltage VX to be measured is applied between input terminals a and b.

This voltage (1) is applied to the voltage terminal of the Pockels element P via resistors R+ and R2. Here, if the voltage VX
Even if an abnormally high voltage occurs in the input surge protection circuit, the nonlinear element Z (for example, a Zener diode) of the input surge protection circuit operates and absorbs the abnormally high voltage, so that the Pockels element P will not be damaged.

When a voltage Vx is applied to the Pockels element P via the resistors R+, R2, the light d+ (usually a laser beam) passing through the Pockels element P at fFL in the input fiber 2 is modulated. Since the degree of modulation changes depending on the magnitude of the applied voltage VX, by detecting the light d2 outputted through the output fiber 3 in the main body 5, the voltage value Vx of the object to be measured can be estimated. can be done.

Here, as described above, it is assumed that it is desired to perform calibration when the voltage Vx is at the zero level. In this case, a light pulse d3 having a waveform as shown in FIG. 2, for example, is applied to the solar cell E via the control fiber 4. In synchronization with this light pulse d3, the solar cell E generates a certain voltage, so that the FETQ is turned on. That is, the electrical terminals of the Pockels element P appear to be short-circuited, and the voltage across them becomes zero volts.

In this way, by applying light that excites the solar cell E through the control fiber 4, it is possible to turn on FE1'Q and apply a zero level voltage to the Pockels element P.

In addition, in order to increase the speed, the control fiber in Fig. 2 is
A high-speed pulse circuit may be used at the solar cell E, using the power source to continuously excite the solar cell E, and providing a fourth fiber as a signal line.

[Effects of the present invention] According to the present invention, the following effects can be obtained.

(2) As shown in FIG. 1, the voltage Vx can be measured with the sensor section 1 separated from the main body section 5.

Furthermore, since all the lines connecting the sensor 9 part 1 and the main body part 5 can be made of optical fibers, a voltmeter with high insulation and high withstand voltage can be realized.

(2) Moreover, since all the lines connecting the sensor 9 part 1 and the main body part 5 are optical fibers, the voltmeter can be operated normally even in a noisy environment.

[Brief explanation of drawings]

FIG. t-diagram and FIG. 2 are diagrams showing an example of the configuration of the sensor section 1 of FIG. 1. DESCRIPTION OF SYMBOLS 1... Sensor part, 2... Input fiber, 3... Output fiber, 4... Control fiber, 5... Main body part,
DESCRIPTION OF SYMBOLS 10... Input surge protection circuit, 12... Zero potential generation l path, P... Electro-optic effect element, Q... Switch element, E... Element, Z... Nonlinear element, R+, R2
···resistance.

Claims (1)

[Claims] It is equipped with an electro-optic effect element capable of inputting and outputting light through an optical fiber and modulating the output light by an electro-optic effect, and an object to be measured is connected between the electrical terminals of the electro-optic effect element. In a device that applies a voltage and measures the voltage of a measurement target through output light modulated by the voltage, the control optical signal is provided between the electrical terminals of the electro-optic effect element and applied from the outside. A voltmeter comprising: a circuit that enters a short-circuit state in synchronization with the above, and is capable of applying a zero-level potential between electrical terminals of the electro-optic effect element by controlling the optical signal.