The first step: look at it once and see it twice. The third step: AC to see the power, DC to find the coil Step 5: Look up and down, left and right, and then the off-screen device Uv Curing Film For Mobile Tablet Uv Curing Film For Mobile Tablet,Tempered Glass For Mobile,Phone Curve Edge Protector,Local Tempered Glass Shenzhen TUOLI Electronic Technology Co., Ltd. , https://www.hydrogelprotector.com
Once: circuit breakers , disconnectors , current, voltage transformers, transformers, etc. Understand the functions of these devices and the commonly used protection methods, such as transformers generally need to install over current protection, current quick-break protection, overload protection, etc., master the basic principles of various protection; then find the conversion and transmission components of primary and secondary equipment, The effect of one change on the second change.
Step 2: After watching AC, see DC
First look at the AC circuit of the secondary diagram, as well as the characteristics of the electrical quantity change, and then find the "fruit" of the DC loop from the "cause" of the AC quantity. The general AC loop is simpler. 
The AC circuit generally starts from the power supply and contains two parts: the AC current and the AC voltage loop. First, find out which current transformer or which group of voltage transformers are used to supply power (current source, voltage source), and the converted current and voltage. The role, their relationship with the DC loop, and the corresponding electrical quantity are reflected by which relays.
The fourth step: the coil corresponds to the contact, the contacts are connected into a line
After finding the coil of the relay, find the loop where the corresponding contact is located. Generally, the contact is connected to another loop. In this loop, other relay coils may be connected in series, which is caused by the coils of other relays. Its contacts are connected to the other circuit until the logic function preset in the secondary circuit is completed.
Mainly for the expansion diagram, terminal diagram and post-screen equipment installation diagram. In principle, it is viewed from the top to the bottom and from the left to the right, together with the equipment outside the screen. Remember these 5 jingles, then you can easily solve them!
Electrical secondary circuit look at the picture port
Look at it once, then look at it twice, watch the exchange, and watch the DC. AC look at the power supply, DC line-up diagram coil corresponding to the contact, the contact is drilled into an online order, the screen device is connected.