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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Lightning indicator. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Protection of equipment from emergency operation of the network, uninterruptible power supplies In No. 4 of the magazine "Electrician" for 2005, my article "Lightning and how to deal with it" was published, while in section 3 "Prospects" it was said at the end: "While the search for optimal solutions for active protection is ongoing ...". Over the past time, or rather, over the last stormy summer, I managed not only to work out the scheme, but to repeatedly test it in thunderstorm conditions. The idea of an active sensor of an approaching lightning discharge has already been described in the previous article in paragraph 3, where a picture of the device is shown in Fig. 12. Here it is shown in Fig. 1, where A is an antenna or other receiving element; IM - lightning indicator, more precisely, an electrometric cascade; VBU - temporary control unit; PL - communication line with the Internet; VK - switch.
Before explaining the operation of the device, it is necessary to look into the history. And it was in 1602. Here is how Chizhevsky himself told about it. When it came to priority, he remembered Duino Castle on the Adriatic. On one of its bastions, a spear has been fixed since time immemorial. There was always a soldier on watch and watching the weather. If a fiery glow appeared on the tip of the spear or sparks jumped, the sentry rang the bell, warning the surrounding residents and fishermen of impending bad weather. You also need to remember the "Fires of St. Elmo", which appeared on the tops of the masts of sailing ships in a thunderstorm. This and many other similar cases confirm the occurrence of atmospheric currents in the period before the lightning discharge. The physics is clear, now you just need a good technical execution. The scheme shown in Fig. 2 is not a dogma. Schematic solutions on a different element base are possible, however, the logic of work is accepted as correct. This is confirmed by the fact that a subsequent search on the Internet showed the presence of a similar solution in 2001 at the Ostankino TV tower!
R1 - MLT0,5 200 kOhm
Warning system about possible lightning strikes into tall objects When approaching objects of a thundercloud, the presence of a lightning warning system allows you to timely remove people from the external elements of these objects, turn off equipment that can be damaged by lightning strikes, and also take other measures to prevent the dangerous effects of lightning on electrical, radio engineering, electronic equipment of objects. The system consists of corona current sensors installed at the top of the object, a protection device in case of direct lightning strikes into the sensor, an electronic unit that signals the danger of a lightning strike into the object when the threshold value of the corona current is exceeded. The electronic unit contains a delay to turn off the danger signal in case of accidental disappearance or reduction of the corona current below the threshold value. Technical specifications The lightning strike danger signal is issued 5...10 minutes before the strike and is removed 15...20 minutes after a steady decrease in the corona current from the electrodes below the threshold value. Depending on the wishes of the customer, the system can be supplemented with devices for automatic photography of the lightning channel, measurement of the lightning current. Advantages over analogues The system has no analogues. Readiness degree The upgraded lightning warning system was installed in April 2001 at the Ostankino television tower and was tested during the 2001 thunderstorm season. Financial and economic indicators The cost of the system depends on its configuration. With a simple lightning warning system, it is approximately 2 million rubles. When equipped with devices for photographing the lightning channel (Fig. 3) and measuring the lightning current, the cost will be 4 million rubles. (prices are as of 01.09.2002).
Functional composition of the circuit Elements R1, R8, HL1, HL4 are indicators, respectively, of supplying power to the network and turning on the communication line; VD1 and C1 are a half-wave rectifier, and R2, R3 and R4 are a voltage divider for loads. An electrometric cascade is made on the HL2 thyratron, where C2 is a storage capacitance, R6 is a charging resistance, C3 is an integrating capacitance in the antenna circuit, K1.1 is the working winding of the RES32 relay, and diodes VD2 and VD3, respectively, for shunting extra currents when the current circuits of the relay are broken . On the thyratron HL3, a time relay is made, where R5 and C4 are an integrating circuit, R7 is the resistor for setting the initial current in the thyratron grid circuit, and K1.2 is the fender winding of the RES32 relay. Contact K1.2 - relay contact for turning on an external control unit, the diagram of which is shown in Fig. 4.
Operation of the device The electrometric cascade on the thyratron MTX-90 has a very high sensitivity to the grid current, so you need to set the sensitivity level by changing the anode voltage using the resistor R3. Install like this. In weather without visible thunderstorms and with antenna A connected, the anode voltage on HL2 is increased until it trips, which will be visible visually from the flashes inside the thyratron bologna. After that, the voltage is slightly reduced, thus setting a certain lower threshold of failure. That's all the adjustments. The device is in standby mode, since the time relay will always switch the relay to the operating position after a specified time (in this case, after 20 s), i.e. when its contacts K1.1 and K1.2 are closed. Therefore, the indicator on HL4 "Line on" is lit. A pre-thunderstorm situation is created, then under certain conditions the thyratron HL2 will start to work. If its response frequency is high enough, then the timer will not have time to operate, therefore, the contacts K1.1 and K2.2 will be open. If you are going to protect only your own computer, you need the actuator circuit shown in Figure 4. If you are concerned about the protection of the electronic components of the wired network in the communication line, then the actuator is selected depending on the specific circumstances. The principle of its operation is described in No. 4 of the Electrician magazine. Additionally introduced: KN - locking button, connector X1 for connection with a lightning indicator, and also introduced X2 and X3 for a television cable. In the case of using the control unit to protect the electronic units of the network, it is apparently necessary to introduce electromagnetic relays with the appropriate number of contacts in their input and output circuits of the units. Possible problems It is, of course, an antenna. Options. PC protection in the apartment. I live on the second floor of a 9-story building, so there is no option other than a pin on the balcony yet. On this pin and there were all the real checks last year. Perspective - I expect thunderstorms and I want to connect the input of the lightning indicator to the free wires of the reduction from the communication network on the roof. I hope for success. Communication line equipment protection option. Here, the indicator is definitely next to the equipment, and the antenna is on the roof, as in Ostankino. Author: A.G. Belyavsky
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