Color TV simple protection socket circuit diagram

At present, the power supply of color TVs is an electronic switching power supply. When the mains voltage is out of phase and results in a 380V voltage input, the action speed of the protection device must be faster than the working speed of the electronic switching power supply to effectively protect the color TV from being However, some color TV protectors currently on the market cannot do this. Even if the color TV protection device is installed, accidents of burning out the color TV due to the wrong phase of the power supply often occur. The reason is mostly because the protector has not yet been installed. During the operation, the color TV was damaged. The simple protection socket introduced in this article can quickly act to blow the fuse under phase misalignment conditions , effectively protecting color TVs.

The circuit of this device is shown in Figure 1. It is composed of the main components - varistor MY and triac VS. The main function of MY is to absorb power grid clutter pulses and prevent large current impacts at the moment of startup. Because it is at the first pass of the color TV power supply, it has the effect of purifying the power grid, reducing interference, and making the screen image clearer; VS is an electronic The switch can quickly turn on when the power grid is out of phase to generate a strong short-circuit current that blows the fuse FU, thereby cutting off the power supply to the color TV. The specific working process is as follows: When the mains power grid voltage is normal, VS is in a cut-off state due to insufficient trigger current, and the color TV is powered and works normally. Once a phase misalignment accident occurs, the input voltage will rise to 380V. At this time, VS is quickly triggered to conduct. At the moment of phase misalignment, due to the voltage dividing effect of R2 and R3, the voltage input to the color TV is only UO=Ui ×R3/(R2+R3)≈230(V), this voltage value will not damage the color TV. At the same time, the conduction of VS will cause the current of the protector circuit to surge, and FU will quickly fuse and cut off the power supply.

The component list is shown in the table below:

During debugging, use a 1kW coupling transformer to adjust the mains voltage to about 300V, connect its output to Ui of the device (note: do not insert any electrical appliances into CZ during debugging!), and adjust the size of R1 , so that VS is just turned on, FU is blown , and debugging is completed, indicating that the socket is protected.