Color TV’s power are now electronic switching power supply, when the mains voltage is 380V result of phase voltage input, its movement speed protection devices must be faster than the working speed electronic switching power supply can not effectively protect the TV damage, but the current TV commercial some protection but can not do this, despite the installation of the TV protection, but also because of frequent power TV-phase and burn accident, reason, mostly in the protection not action, the TV has been damaged. This article describes the protection of this simple socket-phase conditions in the rapid movement from the fuse blows, play a role in the effective protection of color TV.
The device of the circuit shown in Figure 1. It is a major component – and two-way thyristor varistor MY VS composition. MY main role is to absorb the clutter power pulse, high current instantaneous power to prevent the impact, because it is in the first pass color TV power supply, a clean power supply, reducing the interference, the screen image more clearly the effect; VS is the electronic switch , it quickly when the power conduction-phase short-circuit current to have a strong FU blown fuse, thereby cutting off the power supply of color TV. Specific work process is as follows: When the normal electricity grid voltage, VS is due to lack of trigger current cut-off state, have electricity and TV work. In the event of an accident-phase will lead to the input voltage up to 380V, then VS is triggered quickly turn in the wrong phase of the moment, R2 and R3 as the role of the partial pressure, so that the voltage input to the TV only UO = Ui × R3 / (R2 + R3) ˜ 230 (V), the voltage will not damage the TV. At the same time, VS will conduction current surge protection circuit, FU rapidly fuse and cut off the power.
Components list below:
Debugging, the coupling with a 1kW transformer 300V will be raised about the utility voltage, its output is connected with the unit Ui (Note: When debugging the first not on the CZ into any electrical appliances!), Adjust the size of R1 so just turn VS, FU fuse, commissioning is completed, that protection socket