The first cause of a power surge are as strange as we are. Today built-in appliances, appliances for domestic use, consumes sufficient power, while the inclusion of which the load on the network increases, the voltage decreases. Reverse jump occurs at the same time disconnecting devices from the network. Another cause of a power surge, now up, is an open network of wire. This files most often neutral. When poor contact or mechanical damage to the wire thoret. And then the whole network will be under increased tensionm to 380 V. the same happens in thunderstorms, or when trees fall on the power line. In rural areas the cause of overvoltage can be lightning. Even if she doesn't get into the wiring, it can induce a high voltage.Of course, the surge protection of your house and appliances is the main task of every prudent master. The most common devices for protection from power surges today are the voltage regulators and uninterruptible power supplies. Uninterruptible power supplies are used where unacceptable power outages. Such devices are used in hospitals, in large computer centres, airports, etc. They not only protect from power surges, but go into standby power mode during a power failure.Voltage stabilizers regulate the voltagesupplied to household appliances. The type of stabilizers are Electromechanical, solenoid and relay. In Russia the greatest distribution was received relay stabilizers. They have the highest rate of voltage stabilization, characterized by small dimensions, low cost, low noise, durability.