Device for finding a break in the wiring

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The topic of the article is similar to the previous one:

High-voltage pulse generator for searching for a break in the power line

This device allows you to determine the location of the break in the electrical wiring of the house. Thus, you can easily repair the wiring in the house in the event of a break.

This method in electrical engineering is called acoustic. It is based on listening at the place of damage to sound vibrations (claps) caused by a spark discharge. Typically, a gap in the wiring ranges from 0.5 ... 2 mm. Such a gap easily breaks through a voltage of 1 ... 3 kV DC. Simplified diagram in Fig.1.

Uu - boost voltage source before breakdown.

Ru- internal resistance of the voltage source.

If there is low resistance at the breakdown site, there will be no cotton. The source will be discharged and the voltage will not rise. To avoid this, you need to put a spark gap in the circuit circuit (artificial gap about 1 mm). And in order for the breakdown to be clearly audible and visible, add a high-voltage capacitor. Diagram of the device in Fig.2.

Typically, a wire break is located at a depth of 1 ... 2 cm in the plaster or in the junction box. The place of damage is easily detected by a light flash and by the sound of a discharge popping.

Before searching for a break in the section of the electrical network, you need to turn off all electrical consumers. The high voltage of the device can damage the insulation of the electric windings. motors and other electronic devices. And be sure to follow the electrical safety precautions (3).

Before this, it is useful to use a high-frequency generator and a finder and approximately determine the location of the damage (2). And also measure the capacitance of the wiring to the point of damage to the cable APPV 2 * 2.5, the capacitance of 1m is approximately equal to 80-100 pF. Then connect ~220 v power to the high-voltage device (see the diagram of the device in Fig. 4.) and a line with a break to the output terminals "0" and "1" or "2". Press the SA1 button and hold for about 3 seconds. To the rank. If the button is held longer, the discharges will be repeated as the voltage accumulates on the capacitor C2.

The device itself consists of non-deficient parts. Transformer Tr1 from a horizontal scan of a black and white TV. The P35 arrester can be replaced with a homemade one.

It is made of a piece of foil fiberglass with dimensions 30 * 30 with a round hole in the center with a diameter of 15 mm. The foil has been removed in the middle. On the edges there are 2 holes for connecting wires, see Fig.3.

From each platform, 2 pieces of copper wire with a diameter of 1 mm are soldered towards each other with a gap of 3 mm. A breakdown will occur in the gap, with the calculation of 1 mm = 1 sq. Such an arrester P1 is installed in the circuit to protect the high-voltage transformer Tp1. When discharged in the factory P35, the sound is very weak and does not interfere with listening to the discharge in the email. house wiring.

Device diagram

The device is a generator of high-voltage pulses on a thyristor. Capacitor C2 K75-53 1 uF for a voltage of 5 kV. It can be replaced by several smaller capacitors, but the total capacitance should be about 1 μF, the operating voltage should be at least 5 kV.

The ST1 thyristor control circuit is taken from (4). The ratings of the circuit parts are indicated on the circuit diagram. The device is assembled in a small plastic case, see photo. Neon lamp L1 is needed to signal the mains voltage 220v to power the device.

The use of a break detection device

Now two examples of using the device from my practice.

1. Reduce the cable from the VHF antenna. The resistance between the screen and the central core, according to the tester, is 100 ohms. Should be about 5 ... 10 ohms. When connecting the device to the cable, one person pressed the SA1 button, and I watched the antenna and cable in the evening. Sparks were visible under the right bolt connecting the cable to the antenna cable. The right bolt was more tightened. Transitional resistance dropped to 8 ohms.

2. It was necessary to repair the electrical wiring in the house. The electric lamp in the room went out. The lamp is intact and in good condition. Turned out the lamp. Shorted the ends in the cartridge. To a separate line extending to the lamp holder connected the wires extending from the device "0" and "1". When the SA1 button of the device was pressed, discharges were heard in the wiring coming out of the ceiling at the break point. The gap is easily repaired.

Photo of the device.