JPS61128178A - Withstand voltage test of insulated cable - Google Patents

Abstract

PURPOSE:To perform a test without compelling a worker to watch display carefully, by providing a voltage peak hold circuit for holding peak voltage and a display means for displaying peak voltage and detecting dielectric breakdown voltage from the indication value of said display means. CONSTITUTION:A peak hold circuit holds the peak value in the pulsating current outputted from a rectifier circuit 11 to output the same to a panel meter 14 through a display adjusting amplifier 13. When the voltage value of an induction coil flowed to a secondary coil 5 becomes high and dielectric breakdown is generated in an insulated cable and an excessive current is flowed to the secondary coil 5, AC of a primary coil 4 is blocked by an overcurrent detector 6 and a breaker 7 and AC of the secondary coil 5 is extincted. At this time, a peak hold circuit 12 has held the AC voltage value immediately before distinction and said voltage value is displayed on the panel meter 14 as it is. Because the detection of breakdown voltage is not performed by a voltmeter but by the panel meter 14 in this method, it is unnecessary that a worker watches display carefully.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention 1] The present invention relates to a method for testing voltage resistance variations of an insulated cable.

[Technical Background of the Invention] Conventionally, before an insulated cable is shipped from a factory, several types of tests have been conducted to confirm whether the manufactured insulated cable complies with the conditions required by the user. ing.

One of these tests is an AC withstanding voltage test.

This involves applying high-voltage alternating current between the electrodes that sandwich the insulator of the manufactured insulated cable (for example, the center conductor and the water-side electrode when the insulated cable is immersed in water), and determining the voltage at dielectric breakdown. This is a test to confirm whether or not the voltage value is within the conditions, and is carried out using, for example, a device as shown in FIG.

In the figure, 1 is a 100cm commercial AC, 2 is a slideac that varies the voltage, 3 is a pilot motor that drives the slideac 2, 4 is a primary coil to which variable AC is applied, and 5 is a high-voltage induced alternating current. secondary coil, 6 is 2
An overcurrent detector detects overcurrent on the side of the secondary coil 5; 7 is a circuit breaker that cuts off alternating current on the side of the primary coil 4 in response to a detection signal from the overcurrent detector 6; 8 is magnetically coupled to the secondary coil 5; The detection coil 9 is a voltmeter connected to both ends of the detection coil 8 and displays the voltage of the secondary coil 5.

When testing, first, both ends of the secondary coil 5 are
Connect the insulator of the insulated cable to be tested (not shown) between the electrodes.

Next, press the start switch S W + to operate the pilot motor 3 and move the Slide Duck 2 in the pressure increasing direction. As a result, a high-voltage M conducting current is generated in the secondary coil 5, and the pointer of the voltmeter 9 moves in accordance with the voltage value.

When the voltage value of the induced alternating current flowing through the secondary coil 5 increases, dielectric breakdown occurs in the insulated cable, and an excessive current flows through the secondary coil 5, the detection signal output from the overcurrent detector 6 causes the circuit breaker 7 to be activated. The alternating current of the primary coil 4 is cut off. As a result, the alternating current in the secondary coil 5 also disappears, but the reading on the voltmeter 9 immediately before this extinction is taken as the dielectric breakdown voltage.

[Problems with Background Art] However, according to the conventional test method as described above, overcurrent is detected at the moment when the voltage applied to the insulated cable, that is, the induced alternating current generated in the secondary coil 5 reaches the dielectric breakdown voltage. Since the alternating current flowing through the primary coil 4 is interrupted by the operation of the circuit breaker 6 and the circuit breaker 7, the reading on the voltmeter 9 must be checked in a very short time.

However, since the test operator must constantly keep an eye on the voltmeter 9, there are problems in that the degree of fatigue is high and the reading error is also large.

[Object of the Invention] The present invention has been made in view of the above-mentioned conventional circumstances, and involves applying high-voltage alternating current between electrodes sandwiching the insulator of an insulated cable to reduce the withstand voltage change from the dielectric breakdown voltage of the insulated cable. The purpose of the present invention is to provide a withstand voltage testing method for insulated cables that does not require a worker to keep a close eye on a voltmeter during testing and does not cause detection errors in dielectric breakdown voltage.

[Summary of the Invention] That is, the insulated cable of the present invention obtains high-voltage alternating current using a power supply device consisting of a primary coil to which alternating current whose voltage is adjustable and a secondary coil which generates induced alternating current, and which generates high-voltage alternating current. When applying an alternating current between the electrodes of an insulated cable sandwiching an insulator and testing the dielectric strength of the insulated cable based on the dielectric breakdown voltage, the secondary coil of the power supply device is magnetically coupled to the secondary coil. a rectifier circuit that inputs the induced alternating current generated in the detecting coil, a voltage peak hold circuit that inputs the direct current output from the rectifier circuit and holds the peak voltage, and a display means that displays the peak voltage. and detecting the dielectric breakdown voltage from the indicated value of the display means.

[Embodiment 1 of the Invention Hereinafter, details of an embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing details of one embodiment of the present invention. In this figure, parts common to those in FIG. 2 are given the same reference numerals.

In the figure, 1 is a 100V commercial AC, 2 is a slider that varies the voltage, 3 is a pilot motor that drives the slider 2, 4 is a primary coil to which variable AC is applied, and 5 is a secondary coil where induced AC is generated. 6 is an overcurrent detector that detects overcurrent on the secondary coil 5 side, 7 is a circuit breaker that interrupts the alternating current on the primary coil 4 side based on the detection signal of the overcurrent detector 6, and 8 is the secondary coil 5 A detection coil 9 magnetically coupled to the detection coil 8 is a voltmeter connected to both ends of the detection coil 8 to display the voltage of the secondary coil 5.

The above points are similar to the configuration when implementing the conventional method, but in the withstand voltage test method of this embodiment, the detection coil 1 which is indirectly magnetically coupled to the secondary coil 5 is connected to the secondary coil 5 side.
072 is provided, and the output of this detection coil 1o is connected to the rectifier circuit 11.
The pulsating current is input into the peak hold circuit 12, and the resulting pulsating flow is input into the peak hold circuit 12.

The peak hold circuit 12 has the same configuration as those used in various electronic devices, that is, it is a circuit consisting of an operational amplifier, a diode, a capacitor, an FET, etc. is held, and the panel meter 1 is displayed via the display adjustment amplifier 13.
This is what is output to 4. In addition, peak bold circuit 1
2 is connected to a reset circuit 15, and the held peak value can be cleared by the reset request switch SW2.

Therefore, in the withstand voltage test method of this embodiment, both ends of the secondary coil 5 are connected between the electrodes of the insulated cable to be tested, with the insulator sandwiched between them, and the pilot motor 3 is driven. When the slider 2 is moved and the voltage of the primary coil 4 is increased, an induced alternating current is generated in the secondary coil 5.

At this stage, while checking the degree of increase in the value indicated by the voltmeter 9, the display adjustment amplifier 13 is adjusted so that the value indicated by the panel meter 14 corresponds to the value indicated by the voltmeter 9.

When the voltage value of the induction coil flowing through the secondary coil 5 becomes high and dielectric breakdown occurs in the insulated cable and an excessive current flows through the secondary coil 5, the overcurrent detector 6 and the
The alternating current of the primary coil 4 is cut off by the device 7, and the secondary coil 5
communication disappears. At this time, the peak hold circuit 12 is holding the voltage value of the alternating current flowing directly through extinction, and that value remains displayed on the panel meter 14. i.e. 1
Even when no alternating current flows through the secondary coil 4 and the secondary coil 5, the panel meter 14 reliably indicates the dielectric breakdown voltage.

As described above, in the method of this embodiment, the dielectric breakdown voltage is detected not by the voltmeter 9 but by the panel meter 14 connected to the peak hold circuit 12, so the operator does not need to keep an eye on the display.

Note that the above-mentioned detection coil 10, rectifier circuit 11, peak hold circuit 12, display adjustment amplifier 13, panel meter 14, and reset circuit 15 can be configured as one device, and the primary side of the detection coil 10 can be shaped into a connector. For example, the method of the present invention can be carried out simply by connecting the voltmeter of a withstanding voltage tester used in conventional tests to both poles of the detection coil.

[Effects of the Invention] As explained above, according to the method of the present invention, a rectifier circuit, a voltage peak hold circuit, and a display means are provided on the secondary coil side, and the breakdown voltage is detected from the final indicated value of the display means. Therefore, the operator is not forced to pay close attention to the display.
Further, it is possible to perform a withstand voltage test on an insulated cable without causing a detection error.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the structure of the method of the present invention, and FIG. 2 is a block diagram showing the structure of the conventional method. 1・・・・・・・・・・・・Commercial exchange 2・・・・・・・・・・・・Sly duck 3・・・・・・
......Pilot motor 4...
...Primary coil 5...Secondary coil 6...Overcurrent detector 7...
・・・・・・・・・'! xl17i device 8.10...Detection coil 9...Voltmeter 11......Rectifier circuit 12...
...Peak hold circuit 13...
...Display adjustment amplifier 14...
・Panel meter 15・・・・・・・・・Reset circuit agent Satoshi Suyama − (1 person)

Claims (2)

[Claims] (1) High-voltage alternating current is obtained by a power supply device consisting of a primary coil to which alternating current with adjustable voltage is applied and a secondary coil which generates induced alternating current, and this high-voltage alternating current is passed through the insulator of the insulated cable. When performing a withstand voltage test of the insulated cable from the dielectric breakdown voltage applied between the electrodes, a detection coil magnetically coupled to the secondary coil of the power supply device and a detection coil magnetically coupled to the secondary coil are used. a rectifier circuit that inputs an induced alternating current, a voltage peak hold circuit that inputs a direct current output from the rectifier circuit and holds a peak voltage, and a display means that displays the peak voltage, and a display means that displays the indicated value of the display means. A withstand voltage test method for an insulated cable, comprising detecting the dielectric breakdown voltage from the dielectric breakdown voltage. (2) Connect an overcurrent detector that detects overcurrent to the secondary coil of the power supply device, connect a breaker that interrupts the current according to the detection signal of the overcurrent detector to the primary coil, and 2. A withstand voltage test method for an insulated cable according to claim 1, wherein the value displayed on the display means after the alternating current of the secondary coil disappears due to operation is the dielectric breakdown voltage.