JPH11108967A - Isolation apparatus for withstanding high voltage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a high withstand voltage between an input and an output circuits simply by setting a light-emitting and a light-detecting elements at end faces of an optical fiber to be integrally united with the optical fiber and using the unit. SOLUTION: An amplification signal from an amplification circuit 29 is supplied to a voltage-frequency conversion circuit (V/F) 30. A measurement signal, i.e., voltage signal is converted to a frequency signal and an output signal is supplied to a light- emitting element 31 such as a light-emitting diode or the like constituting an electooptic conversion element (E/O). The light from the light-emitting element 31 is converted to an electric signal by a light-detecting element 33 constituting an optoelectric conversion element (O/E) set at the side of an output circuit 26 via an optical fiber 32. An optical signal detected at the light-detecting element 32 is supplied to a frequency- voltage conversion circuit (F/V) 34 and converted to a voltage signal. Further, a control signal from a control part 42 is converted to an optical signal via a light-emitting element 44 of an E/O 43 and transmitted to a light-detecting element 46 of an O/E 47 via an optical fiber 45. The optical fiber of a length of approximately 4-5 cm is used, so that between an input and an output circuits can be easily turned to withstand high voltages.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct current amplifier (DC amplifier) for measuring a voltage or the like, and more particularly to a high voltage isolation device suitable for use in a high voltage isolation DC amplifier.

[0002]

2. Description of the Related Art Conventionally, in an isolation DC amplifier or the like, an isolator circuit is provided between input / output circuits in order to isolate input signals of a sensor, a voltage source, a current source and the like and extract a predetermined output voltage. I have.

FIG. 4 shows an example of the configuration of a conventional isolation device. In the system diagram of FIG.
For example, an input signal S to be measured supplied from a sensor or the like supplied to _IN is amplified by the amplifier circuit 1, FM-modulated by the modulator 2, and supplied to the isolator circuit 3.

[0004] The isolator circuit 3 comprises a photocoupler 6, a photointerrupter 7, or a transformer 8 as shown in Figs. 4B to 4D.

As shown in FIG. 4B, the photocoupler 6 has a light emitting element 9 such as a chip-shaped light emitting diode and a light receiving element 10 such as a phototransistor and a photodiode, which are opposed by a transparent resin 11 through which light passes. (The optical path may be the atmosphere), and the whole is covered with an opaque black resin 12 to form a mold, and the external leads 13 are led out of the mold.

As shown in FIG. 4C, an optical path between the light emitting element 9 provided on the base and the light receiving element 10 is exposed, and the photo interrupter 7 receives light from the light emitting element 9 provided in one rising portion of the base. The light 14 receives the light 14 through the window 15 and the window of the light receiving element 10 provided at the other rising portion, and the external lead 13 is led out from the lower side of the base. .

In an optical coupling element such as the above-described photocoupler 6 and photointerrupter 7, when an electrical input signal is led to an output circuit, it is isolated by light.

When the transformer 8 is used, as shown in FIG. 4D, a primary winding 17 and a secondary winding 18 are wound around a ring core 16 and an input signal supplied to the primary side is supplied to the secondary side. When magnetic induction is performed and an input signal is led to an output circuit, the input signal is magnetically isolated.

The modulated signal output through the various isolator circuits 3 as described above is demodulated by a demodulator 4 and then a carrier component is removed through a low-pass filter (LPF) 5 to output a signal. Output to T _OUT .

Therefore, the measured voltage and the like supplied to the input terminal T _IN can be isolated and taken _out to the output terminal T _out side.

[0011]

According to the isolator circuit 3 described in the above conventional configuration, the input circuit and the output circuit can be electrically separated.

However, as shown in FIG. 5, a high-voltage 5
When a DC voltage fluctuation on a line having a potential of about kV to 10 kV is to be measured, for example, the measured DC voltage 1
When measuring a fluctuation between 105 V and 95 V with respect to 00 V, the first voltage on the input side of the isolation amplifier 19 is measured.
A DC voltage of ± 5 V = 10 V may be input to the signal source 20, but the ground terminal 22 on the input side of the isolation amplifier 19 to which the second signal source 21 is supplied is connected to the ground E.
In between ₁ are given the potential of 5kV to 10 kV.

Therefore, a high voltage of 5 kV to 10 kV is supplied between the ground E ₁ on the input side of the isolation amplifier 19 and the ground terminal _TG on the output side.
V _C0 and V _E0 and V _C1 and V _E1 in FIG. 5 indicate first and second power supplies.

In the above-described isolation amplifier 19, if the input and output are isolated using the photocoupler 6 or photointerrupter 7 as shown in FIG. 4B or FIG. In the photo coupler 6,
The distance d ₀ between the light paths made of the transparent resin 11 between the light emitting element 9 and the light receiving element 10 is about 1 mm, and the distance d ₁ of the space between the light emitting element 9 and the light receiving element 10 in the photo interrupter 7 is also 2 to 3 mm. is there.

Therefore, substantially 5k is set between the light emitting element 9 and the light receiving element (between the ground terminal 22 and the _{TG of the} input / output circuit).
When a high voltage of V to 10 kV is applied, the photocoupler 6
Or the photointerrupter 7 is destroyed, or high voltage is leaked, so that isolation between input and output cannot be performed.

Similarly, when the transformer 8 shown in FIG. 4D is used, the primary winding 1 wound on the ring core 16 is also used.
In order to improve the breakdown voltage by causing leakage through the stray capacitance C _S between the secondary winding 7 and the secondary winding 18, the transformer must be increased, the insulation in the winding must be increased, or the like. ,
There was a problem that isolation could not be easily performed.

An object of the present invention is to provide an isolation device for a high withstand voltage which has solved the above-mentioned problems, and an object to be solved by the invention is to provide a high voltage withstanding voltage between input and output circuits. In order to obtain an isolation device that can be easily achieved.

[0018]

The high-voltage isolation device of the present invention comprises an input circuit having an amplifier circuit to which a high-potential input signal is supplied, and an output circuit that insulates and outputs the input signal. A high-voltage isolation device, wherein an input circuit and an output circuit are insulated via an optical fiber.

Further, the length of the optical fiber is selected so that the creepage distance or the space distance between the input circuit and the output circuit is sufficient to achieve the withstand voltage at high voltage.

According to the present invention, the light emitting and receiving elements are provided on both end faces of the optical fiber, and by using the integrated optical fiber, it is possible to withstand the high voltage supplied between the input and output circuits. A high breakdown voltage isolation device can be obtained.

Further, by appropriately selecting the length of the optical fiber, it is possible to obtain a high withstand voltage isolation device capable of freely selecting a high withstand voltage.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A high-voltage isolation device of the present invention will be described below in detail with reference to FIGS.

FIG. 1 is a system diagram showing an isolation device for a DC amplifier for high withstand voltage according to the present embodiment, FIG. 2 is an explanatory diagram of a standard connection of the isolation device, and FIGS. It is a top view and a side view for explanation showing the state.

FIG. 1 shows an isolation device 24 for high withstand voltage.
Shows the output circuit of the DC amplifier, to the input terminal T _IN of the input circuit 25 the measurement signal Sm such voltage to be measured is supplied.

The measurement signal Sm is ATTX1, and X1 /
Each of the 1000 dedicated input terminals T _IN is connected.

The measurement signal Sm is supplied from an input terminal T _IN and is supplied to an input attenuator (hereinafter referred to as an input ATT) 2
7 is composed of, for example, 1/1000 ATT and an input protection fuse, and is sent to an input changeover switch (INPUT) 28 through an input ATT unit 27.

The output of the input selector switch 28 is
9 to 1 to 1000 depending on the gain (GAIN) setting
Amplified up to two-fold.

The amplified signal from the amplifier circuit 29 is supplied to a voltage-frequency conversion circuit (hereinafter referred to as V / F) 30. The measurement signal, that is, the voltage signal is converted into a frequency signal,
The output signal of F30 is supplied to a light emitting element 31 such as a light emitting diode which constitutes an electro-optical conversion element (hereinafter referred to as E / O).

The light from the light emitting element 31 is transmitted through an optical fiber 32 to a light receiving element 33 such as a photodiode or a phototransistor which constitutes a photoelectric conversion element (hereinafter referred to as O / E) provided on the output circuit 26 side. Is converted into an electric signal.

The light signal received by the light receiving element 33 is supplied to a frequency-voltage conversion circuit (hereinafter referred to as F / V) 34, and the frequency signal is converted into a voltage signal.

The output of the F / V 34 is supplied to a gain adjustment circuit (hereinafter referred to as VAR) 36 after removing unnecessary components such as carriers by a carrier filter 35 for filtering a carrier component or the like modulated by the V / F 30.

The output whose gain has been adjusted by the VAR 36 is the LPF 3
7 and a zero adjustment circuit (ZERO, ADJ) 38 to output to an output terminal _Tout .

The output voltage at the output terminal T _out is zero (ZER
O) point and over (OVER) point detection circuit 40 constantly monitors the ZERO (within ± 100 mV) state and OVE
In the R (± 10.5 V or more) state, the LED and the like are turned on, and supplied to the control unit 42 including a CPU and the like.

Signals are exchanged between the control section 42 and the sheet panel 41. The sheet panel 41 has a setting key, a setting display LED, and the like. Various conditions set on the sheet panel 41 are determined by the control unit 42 and set in the output circuit 26, for example, a calibration circuit (hereinafter referred to as CAL). ) proofing values such 39 are output, for example, are X1 or X2.5 times to the output terminal T _OUT VAR36.

Further, the control signal from the control section 42 is converted into an optical signal via the light emitting element 44 of the E / O 43, and the light receiving element 46 of the O / E 47 provided on the input circuit 25 side via the optical fiber 45. Is transmitted to

Although one optical fiber 45 is shown in FIG. 1, a two-core optical fiber is used here, and a gain setting control signal of the amplifier circuit 29 and a switching control signal of the input switch 28 are respectively provided. The signal is supplied to the amplifier circuit 29 and the input switch 28 via another optical fiber.

In FIG. 1, T _AC is a commercial power connector terminal and is supplied to the high voltage transformer 49 via the fuse F and the power switch SW. Is supplied to the power supply of each circuit of the input circuit 25 and the output circuit 26 via the.

A high-voltage isolation device 2 comprising an isolation DC amplifier having the configuration and operation described above.
The connection method of the input / output signal of No. 4 will be described with reference to FIG.

The non-inverting and inverting input to the terminal T ₁ and T ₂ signal to be measured through the resistor R _e1 and R _e2 from the first input signal source es1 and es2 of the isolation amplifier 19 in FIG. 2 is supplied You. Also, isolation amplifier 1
Common terminal T ₃ of the input circuit 25 side 9 is connected to the shield (common shield) unit.

The other ends of the input signal sources es1 and es2 and one end of the common shield are connected to a second input signal source CMV via a resistor _RC . This second input signal source CM
V corresponds to the second signal source 21 of the high voltage source described in FIG. The second input signal source CMV is connected to the ground potential E _1.

Output circuit 2 of isolation amplifier 19
The output terminals T ₄ and T ₅ on the 6 side are, for example, ± 10 V, 5 m
A (T ₄ ) and 30 mA (T ₅ ), and an output cable is connected between the output device 52 and the ground terminal T ₆ of the isolation device 24 and the ground terminal of the output device 52. It is adapted to connect to ground potential E _1. With such a configuration, in this example, it is possible to provide an output terminal T ₄ having an AC voltage of 8 kV and a withstand voltage of one minute between the output terminal T _{4 and} the input circuit 25 side.

The input / output circuits 25 and 2 of the isolation amplifier 19 in the isolation device 24 used in this embodiment.
As shown in FIGS. 3A and 3B, the lengths of the step-type or graded-type optical fibers 32 and 45 are each set to four.
cm to 5 cm, and the optical fibers 32 and 45 are selected.
The light-emitting surfaces of the light-emitting elements 31 and 44 such as light-emitting diodes and the light-receiving surfaces of light-receiving elements 33 and 46 such as photodiodes and phototransistors are disposed on both ends of the core. And the external leads 13 are led out of the mold.

The external lead 53 is a wiring pattern 55a of a printed circuit board 54 constituting the isolation amplifier 19.
And 55b are fixed by soldering. In this example, the length of the optical fibers 32 and 45 is, for example, 1 cm for 1 cm.
The optical fiber length is selected as having an insulating property to withstand a withstand voltage of kV.

In FIGS. 3A and 3B, the distance D between the wiring pattern 55a on the input circuit 25 side and the wiring pattern 55b on the output circuit 26 patterned on the printed circuit board 54 is shown in FIG. It is arranged along the surface and is selected to be equal to the length of the optical fibers 32 and 45, but the distance D of the printed circuit board 54 between the input circuit 25 and the output circuit 26 is set to a withstand voltage to be isolated. If D = 1 cm and have sufficient insulation property, the optical fiber 32 or 45 is connected to the optical fiber 32 or 45 in FIG. 3B.
May be arranged to be bent in a convex shape as shown by a broken line.

[0045]

According to the isolation device for high withstand voltage of the present invention, by using an optical fiber having a length of 4 to 5 cm, a high withstand voltage (8 kV / 1 minute) between the input / output circuits can be easily achieved. Things are obtained.

[Brief description of the drawings]

FIG. 1 is a system diagram showing one embodiment of a high withstand voltage isolation device of the present invention.

FIG. 2 is an illustration of connection of input / output signals showing one embodiment of the isolation device of the present invention.

FIG. 3 is an explanatory diagram of an arrangement state of an isolator of the present invention.

FIG. 4 is a configuration diagram of a conventional isolation device.

FIG. 5 is an explanatory diagram of a use state of a conventional isolation device.

[Explanation of symbols]

 Reference Signs List 24 Isolation device 25 Input circuit 26 Output circuit 31, 44 Light emitting element 33, 46 Light receiving element 32, 45 Optical fiber

Claims (2)

[Claims] 1. A high-voltage isolation device comprising: an input circuit having an amplifier circuit to which a high-potential input signal is supplied; and an output circuit that insulates and outputs the input signal. A high withstand voltage isolation device characterized in that output circuits are insulated from each other via an optical fiber. 2. The device is characterized in that the length of the optical fiber is selected so that a creepage distance or a space distance between the input circuit and the output circuit is sufficient to withstand a high voltage. The isolation device for high withstand voltage according to claim 1.