Phase trap. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Protection of equipment from emergency operation of the network
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In rural areas, there are constant problems with electricity. Fortunately, I have three phases connected to my house, which allows me to use the electricity network almost uninterruptedly.
Three phases is of course very good, you can connect three-phase equipment like a lathe. But my joy was short-lived (it’s good that I didn’t have time to buy a three-phase machine). It turns out that in our village "three phases" is a very relative thing, since all three of them are extremely rare. It's good if there are two or one. Moreover, they disappear and appear very unpredictably, and since 220 V is taken from one phase, most houses also suffer from power outages. In my case, it is easier, because 220 V can be removed from at least one working phase. Initially, I had to do it manually. I installed three powerful single-phase sockets with neon lights on the shield to indicate the presence of voltage, connecting each to a separate phase, and removed the plug from the wiring of my house. The voltage is gone, you go into the hallway and switch the plug to an outlet where there is voltage.
But this method is very impractical, as it requires constant human control, and if you are not at home, the refrigerator will leak!
After a little thought, I assembled a circuit, which I called a "phase trap", the circuit is shown in the figure. Everything is very simple. There are three low-power network transformers (TVK-110 - the very thing), on the secondary winding of which the voltage is somewhere around 8 ... 10 V. And three powerful relays with windings of 12 ... 14 V. The relay contacts are switching, and connected in series as shown in the diagram.
Rectifier bridges and smoothing capacitors are installed on the secondary windings of the transformers. The primary windings of the transformers are each connected to its own phase, and to the outputs of the rectifiers, the relay windings.
So, let's say there is a "holiday" on our street, that is, there are all three phases. In this case, all relay windings are energized. And all their contacts are in the opposite position shown in the diagram. Then the voltage to the house is supplied through contacts K1.1 from phase L1.
And then something happened again at the substation and phase L1 turned off. The winding of relay K1 is no longer energized, its contacts switch to the position as in the diagram. If there is a phase L2, then the voltage to the house will go through the turnip contacts K1.1 and K1.2. If there is no L2 phase either, but there is still a L3 phase, the voltage to the house will go through the contacts of all three relays from the L3 phase.
Well, if all the phases are not there, then there's nothing to be done. However, the absence of voltage in all three phases is extremely rare for us.
Details. TVK-110 type transformers from an old TV. But you can use almost any transformers with a voltage on the secondary winding of 8 ... 10 V and a maximum current of at least 100 mA. Now there is a wide choice of such parameters. Relay type SCB-1M-1240 with 12 V coil and 40 A at 12 V and 15 A at 230 V contacts and changeover contacts. It can be replaced by another relay with similar parameters, for example, 13F-2-SCL-12VDC-230VAC-15A. Relays are now on sale, too, there is a sufficient choice.
Diodes capacitors - any, of course, within reasonable limits
Author: Lyzhin R.
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