China made the war: SCR Chapter

To tell the truth, I was really touching the SCR time is not long, before I only know this thing function similar to relay, the main control AC load switch. What BT136, BTA06, BTB06 was first seen in an automatic mahjong machine. Because it has always been the study of digital hardware programming or a yard farm, these also disdain, as coarse things.

Once the company received a project, it was the first time to miss a close contact with the SCR. The project is a giant led buried clock, need to look down from the high buildings, Singaporean ghost creative, but the idea is good. I didn't do it at that time. As a technical director, just beginning to dominate some projects, experience, prestige and seniority are not strong enough. There is an old senior engineer has not retired, do the distribution cabinet design is number one, but only this. These engineers are basically 40-50-year-old appearance, knowledge structure aging, young, half a bottle of skills are job-hopping. I was a more than 20 of the boy was also because of nature, just in the eyes of this group of uncles, on their own ability to 1.1 points from being led to lead them. Many of my opinions and proposals have been overlooked, considered by young people to be shortsighted, inexperienced and ambitious, until they are truly recognised. Carefree matter, I began to have a weight, and this project is happening during this period.

Party a requires that the clock in the sun 30 meters above the building visible, you can adjust the brightness, to deal with the industrial area mains voltage changes greatly. We can pre-bury the pipeline, reserve the pit position and carry out the reinforced concrete after we have set the plan. Let's start with the last picture, so explain. The outer ring is about 30 meters in diameter.

I control part of the technology and programming, so the size of the civil no participation, and no one asked me. But the general manager of the day with me to discuss the problem of daylight, color has been set "yellow", but 2000 years or so there is no good four element yellow led, unless imported. I only mentioned 4 requirements, 1. The luminous intensity must be greater than 5000cd/m2, preferably more than 8000; 2. The covered glass must have scattering effect, or the LED arrangement is dense enough; 3.LED cluster tube, modular, waterproof and moisture-proof, easy to replace. 4. Built-in box made of stainless steel in the glow pit. These requirements look pretty good, and the truth is that every one of them has achieved its original purpose.

First of all, high-brightness LED, the calculation can not be imported, the cost is too high (in fact, it is possible to use, but the leadership reluctant). Later used a factory in Ningbo, Yellow led, firing angle only ± 20 degrees, the law intensity 2000CD, the price is 1/10 of imports, brightness indicators only 1/4. This can be said to be the first bad card, triggering a chain reaction. Brightness is not enough, first of all more than 1 time times more, power increased by one times, brightness has been my expected 1/2, the dissipation of heat increased several times.

The general manager thinks that the increase of the LED is a good card, because the purchase of covered glass is convenient. I originally asked to find a high transmittance of the scattering film, sandwiched between two 8mm of tempered glass, now become the following a glass, the above a transparent glass. The second bad card led to increase the number of 50%, and to the scene after the frosted glass stained with dew, basically transparent.

The front said that the senior engineer and volunteered the gun I live, privately designed the cluster pipe PCB, so that the PCB factory processing, and made thousands of pieces. I saw the PCB drawings after a furious, immediately asked the leadership to meet. This cluster tube uses 64 led,8 series and then 8 parallel, the problem is that there is no resistor in the series circuit in parallel. The VF curve of each led has a small difference, 8 series after the difference will be larger, without a dozens of ohm resistor in parallel, will cause the VF small one-way current will increase, until the VF growth to everyone. The maximum operating current of a single LED is usually limited to 20mA, and the lifetime and brightness of more than 20ma,led will drop sharply. Reasoning naturally is I ko others, but I am helpless to that thousands of pieces of PCB can not be used to make a compromise (for today, I absolutely do not compromise), this compromise has brought new trouble. In order for the PCB to be used, the PCB factory to do a manual cutting, but did not place the position of resistance, so that the finished product cluster pipe out of 9 lines, and to add 8 resistors, days general workload. The final project progress was too late, everyone worked overtime for 2 weeks, and stayed up 2 days to reluctantly in the party a stipulated period of entry installation.

Say the stainless steel box, make the structure design is a retired rehiring senior engineer. I do not want to discredit these senior titles of the predecessors, but one point is to point out, the lines such as GE, even if the small difference there is a great difference, there are a lot of people knowledge is not updated, and factory production is not the actual disconnect and so is the design of a good product. The structure of the senior Engineer in fact, the design of the distribution box what the big guy still can, but small electrical appliances will not be very good, if I can not do the brainstorming. Get a reasonable idea, your own refinement can be. Stainless steel strength is very high, basically can not attack the teeth on the screw, with self-tapping screws fixed special-shaped box, disassembly several times fell apart. To be honest, the case of this project only needs to make a hollow Mazaga a shoe box like the lid on the line, do not need a self-tapping screws, unfortunately still no one listens.

Speaking back to the control line, my proposal is to transmit the signal in a cascade, reduce the number of lines, and install the uplink line in each box. If I had initially proposed a thyristor-controlled switch, maybe the solution would be acceptable, but I used a relay. Relay Maintenance Current is not big, can absorb the interference is very large, even I can not guarantee the reliability of the joint level, but if the SCR and optocoupler control, interference problem solved. Another reason for the rejection by senior engineers and leaders is that the transmission of mains main cable termination wiring problem. Due to the first bad card, led with the original plan of more than 3 times times, the overall power from 10 kw to 40KW, the cable needs to be changed from 2.5 Square to 6 square, no 6 square power line is cut into a section and head tapping waterproof connection precedent, is 2.5 square line, outdoor operation to connect more than 10 joints is not easy. In essence, because of the lack of experience, and their own doubts, there is no way to persuade everyone with enough reason, eventually led to a piece of crap like the design on the horse. The final scene of the total junction Pit is a collection of 72 1 square 2 core line, yes no sheath! There is also a fuse board and relay box, which is covered with the same AC power cord as the snake swarm. The clock finally went on for 5 years after the maintenance of our conscience.

In general, the above-mentioned decision-making errors are common, not unique to China, the wayward foreigner is also more

In fact, has not been in-depth contact with the SCR, and I contact the research and development projects have a great relationship. To say a joke, I have been afraid of direct contact with more than 220V high pressure. Reading Junior High School, young ignorance, got a capacitor buck line to the alkaline 5th battery charge, the result was accidentally shorted, a whole layer of more than 10 household power are broken (at that time each house does not install air switch, fuse or use wire instead of), the electric Arc copper sheet is melted. Then there are many times of electricity experience, but the electric shock is not too painful, just don't like this feeling. From this touch high-pressure things on the careful, carefully over the head, even the CRT TV is not afraid to repair, I heard that the high voltage of the color TV package higher, simply do not touch. Over the years, switching power supply, inverter, rectifier, backlight high-pressure plate are weak, not much practical experience. If this kind of electronic products is bad, not smoke, sparks is a dark One, unlike digital circuits, electricity is not, with the hand that tweezers, but also can measure the virtual welding.

The characteristics of SCR is still very strange, my direct image is triggered, do not reverse the power is not turned off. Many textbooks have complicated the introduction of SCR, especially the bidirectional SCR. is the equivalent schematic diagram of two unidirectional SCR.

Until

China made the war: SCR Chapter