Maintenance of a household table lamp, found inside the 220v AC to 12v DC, (with a 12v mirror headlight) Transformer has red, blue, black three into the line, plus or minus two output. Ask why is the three lines? In addition to the line of fire and the zero line, what is the remaining root?
Transformer 3 into the line in the red and blue for the line of fire and the zero line (do not have to distinguish), the black line for the ground, if there is no power cord, you can not (empty). General table lamp with a 2-wire power plug, does not introduce the ground. Because the lamp in the circuit, the human body can not touch, not ground is safe.
There are three lines is normal, because in addition to a line of fire a zero line, there is a ground wire (ground wire is directly connected to the Earth's line, it can be called a safe circuit, dangerous when it put high pressure directly To the earth, be a lifeline.
Transformer is the use of electromagnetic induction principle to change the AC voltage of the device, the main components are primary coil, secondary coil and core (core). The main functions are: voltage conversion, current conversion, impedance conversion, isolation, voltage regulator (magnetic saturation transformer) and so on. According to the use can be divided into: power transformers and special transformers.
You see how it is connected to the law ah ~ which is connected to the power supply is the power cord ah ~ may also be the designer in order to be able to work at 220 and 110 (some countries are 110) and designed. Why did he do so?
