I suggest a simple device that in the event of a power outage will protect the TV, VCR, fridge, etc. from the surge. Typically, when an accident is present in the network voltage 380 V (RMS), bringing all the trouble. In such a situation, the device overvoltage protection is triggered, creating a short circuit. The "broken" tube (fuse or automatic) stop the flow of electricity in the apartment.
Diagram of the device shown in the figure.
Voltage protection operation is approximately equal to 255 V.
In fact, the voltage is slightly more due to the presence in the threshold circuit of the resistor R1. This resistor can be within certain limits to vary the voltage. In the author's version Ucp=270 V. Capacitors C1 and C2 form with R1 RC-chain, which prevents triggering of the device during pulse emission in the network
The scheme works as follows. When the voltage to 270 In Zener diodes VD3, VD4 closed. Also closed and thyristors VS1, VS2. In excess of the RMS voltage over 270 In open Zener diodes VD3, VD4, and to the control electrodes of the thyristors VS1, VS2 enters the opening voltage. Depending on the polarity of photoperiod mains voltage, the current flows either through the thyristor VS1 or VS2 via. When the current exceeds 10 A, triggered the circuit breakers (the tubes), protect electrical devices from burnout.
To configure the device is not required
Without capacitors C1 and C2, the response time does not exceed one half-cycle of mains voltage, but there may be false positives. As with capacitors C1 and C2 reduces the speed of the device, you can do a half-wave circuit with one thyristor (VS1), removing VS2, S2, VD1, VD2 and VD6. The efficiency of the device is retained.
The device is assembled on a small printed circuit Board placed in the housing from the external power supply of the recorder. To check the efficiency of the device by Latri.
This device the author is working flawlessly for over a year, collected more than a dozen. Everyone had only positive feedback.
Literature
1. Veresov G. P., Smolyakov Y. L. Stabilized power supplies of radio equipment. - M.: Energy,1978.
Author: A. Was Pacala, Donetsk; Publication: N. Bolshakov, rf.atnn.ru