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Precautions for parallel power supply of multiple cables - RIFENG CABLES
- cable manufacturers in china
rfcable.com.cn
The following precautions need to be taken into consideration when using multiple cables in parallel for power supply:
1. Problems in parallel connection of cables:
<1. When cables are connected in parallel, the parallel cables must have the same specifications and models, otherwise cables with small cross-sections or cables with large impedance will not Can pass the current corresponding to the corresponding cross-section. Cables with large cross-sections and low impedance will exceed the rated current by a lot and cause heat generation. <2. In principle, the number of parallel cables should not exceed 2 for the wiring between the power distribution cabinet and the equipment or between the switch and the switch. In special circumstances, measures must be taken to increase the contact area of the joint before the number of roots can be increased. <3. The more parallel cables, the more difficult it is to lay the cables. Especially for pipe-through cables, the cross-section of the pipe-through pipe is much larger. 2. Principles to be followed in parallel connection of cables: <1. When operating space permits, the selection should be based on a single cable for power supply. <2. If there is no suitable single cable for the temporary power supply project, the original cable can be used for parallel connection. <3. When selecting cables for parallel operation, the specifications and models of the cables must be consistent. Parallel connection of cables of different specifications and models is likely to cause an accident due to excessive load current of a single cable. <4. When the number of cables in parallel is large, if the extension wiring board is used for wiring, the distance between the connectors should not be too small, otherwise it will Reduce the cross-sectional area of the wiring board and affect its current carrying capacity. <5. Both ends of the parallel cable need to share the same protector. It is not recommended to use multiple low-voltage power supplies.
Rubber-sheathed cables
Rubber-sheathed cables usually use Category 5 copper conductors as conductive cores. During their production and transportation, the copper conductors are often oxidized and discolored, which seriously affects the quality of the products. So how to effectively prevent the oxidation of rubber sheathed cable conductors?
1. Choose high-quality copper rods
In cable production, copper conductors are often purchased from outside. At this time, high-quality raw materials should be selected and the supplier's transportation, delivery, storage and other links should be standardized. For transportation and storage of copper rods, plastic cloth or plastic film can be used to cover the copper rods, and the simplest physical barrier method is used to prevent the copper rods from contacting moist air. At the time of delivery, check the copper rod with naked eyes for signs of blackening, and control the oxidation of the copper conductor from the source.
2. Control of copper rod drawing process
1>. Choose a suitable mold to avoid the variation of the copper rod crystal lattice and accelerate the temperature rise and oxidation of the metal copper.
2>. Check the temperature and humidity of the emulsion before starting the machine to ensure that the emulsion is an alkaline solution.
3>. The take-up and take-up line should keep the copper rod tension uniform and stable, and the surface of the metal copper itself should be dried.
4>. After drawing the bottom plate, seal it with a transparent plastic film and store it in a dry environment.
3. Copper wire stranding and insulation, sheath rubber extrusion process
1>. In the process of twisting, the infusion hose can be used to drip the antioxidant into the copper wire. The dripping standard is based on the surface of the copper wire just soaking, so that a passivation film can be formed on the surface of the copper conductor to avoid oxidation.
2> During the extrusion process, water should be avoided in the end of the thread to prevent the end of the thread from oxidation and blackening.
Electrical performance testing
Electrical performance testing mainly includes conductor DC resistance testing, insulation resistance testing, and finished product voltage testing.
1. The DC resistance of the conductor reflects the electrical transmission performance of the cable, and directly affects the temperature, life, voltage drop, and operational safety of the cable during energized operation. Conductor resistance is mainly affected by the conductor material and cross-sectional area. If the purity of the conductor is low or the cross-section of the conductor does not meet the design requirements, the DC resistance of the conductor will exceed the standard. If this kind of cable is laid in the line, it will increase the current loss, cause the cable conductor to heat up, accelerate the aging of the insulation, and even cause leakage and short circuit. In severe cases, it will cause a fire and endanger the safety of people and property. In the national product standards, there are clear regulations on the conductor DC resistance of cables of different specifications, and the products must meet the standard requirements when they leave the factory.
2. Insulation resistance mainly examines the electrical insulation performance of the cable insulation layer. When the conductor is energized, the insulation layer will play its insulating role to prevent current from leaking through the insulation layer. If this index is unqualified, it will not only cause major safety accidents, but also Will directly endanger personal safety.
3.The finished cable withstand voltage test mainly assesses the reliability of the product under working voltage and finds serious defects in the insulation, but the most important thing is to find the defects in the process, such as: external damage in the insulation, electric field on the conductor Serious defects such as sharp distortion. Of course, insulation thickness, insulation density, and insulation appearance are also the inspection objects of the withstand voltage test.
Principles to be followed when cables are connected in parallel
1. When operating space permits, the selection should be based on a single cable for power supply.
2. If there is no suitable single cable for the temporary power supply project, the original cable can be used for parallel connection.
3. When selecting cables for parallel operation, the specifications and models of the cables must be consistent. Parallel connection of cables of different specifications and models is likely to cause an accident due to excessive load current of a single cable.
4. When the number of cables in parallel is large, if the extension wiring board is used for wiring, the distance between the connectors should not be too small, otherwise it will
Reduce the cross-sectional area of the wiring board and affect its current carrying capacity.
5.Both ends of the parallel cable need to share the same protector. It is not recommended to use multiple low-voltage power supplies.
Two cold knowledge of plug
First. The life-saving three millimeters on the triangular plug:
Do people often complain that the three-wire plug occupies the space? It is not as convenient to use as the two-wire plug. I can’t wait to change the three-wire plug into a two-wire plug. In fact, one of the three-wire plugs is a grounding wire. The grounding wire is not a redundant design, but a "help" String". It is usually connected to the shell of electrical equipment. Once there is a leakage, most of the current flows to the earth from there. In the event of an electric shock, only a small amount of current flows into the human body.
So, where is the three millimeters of the three-wire plug? Yes, it's on the rescue line. Usually the ground wire is three millimeters longer than the neutral wire and the live wire. The reason for this design is that when the plug is inserted into the triangular socket, the ground wire is first connected and then the neutral wire is connected. Therefore, if there is a potential leakage hazard in the electric facilities, the grounding wire has been led to the earth in advance, which also avoids the electrical accident of electric shock!
Second. What are the two small round holes of the two-angle plug used for?
1. Fixing the plug: When the plug is inserted into the socket, there will be a force to fix the plug, which comes from the shrapnel inside the socket. The shrapnel has a small protrusion that just fits into the hole of the plug and gives the socket one Fixed force.
2. Locked plugs: Some sockets are locked. After inserting them, press a switch to insert a metal rod into the hole to avoid being pulled out by others, such as the plug on a vending machine.
3. Factory packaging: Pass a plastic strip through this hole, which is equivalent to a package and cannot be used unless it is opened. For example, the factory can wear a plastic strip with instructions on it to ensure that you must tear the plastic strip and see their instructions before using it.
The difference between round cable and flat cable
First. From the physical performance
1. The difference in appearance: the shape of the flat cable is flat, and the shape of the round cable is round. Therefore, it is easier to increase the tensile galvanized steel wire for the flat cable than the round cable;
2. Differences in the internal arrangement of the cable: the internal conductor cores of the flat cable are arranged according to uniform and orderly rules, mostly in a line or plum blossom arrangement; and the internal conductor cores of the round cable are multi-stranded, which also determines The production cost of round cables is lower than that of flat cables.
3. The difference in physical properties: mainly reflected in the degree of bending and the number of bending. When the number of conductor cores is exactly the same, compared to round cables, flat cables have a larger bending amplitude and bending times, and have a longer service life.
Second. From the chemical performance
1. Different heat dissipation: In the case of the same number of conductor cores, flat cables have an advantage over round cables in terms of heat dissipation.
2. The signal transmission direction is different: the circular structure has the symmetry of the circumferential distribution. Whether it is half-duplex or full-duplex transmission, it is better than the flat shape to be symmetrical in only one direction.
3. The signal shielding effect is different: the internal structure of the round cable is easier to add a shielding layer than the flat cable, and the signal shielding effect is better.
China declares all cryptocurrency transactions illegal
China´s central bank on Friday declared all transactions involving Bitcoin and other virtual currencies illegal, stepping up a campaign to block use of unofficial digital money.To get more news about OKCOIN JAPAN, you can visit wikibit.com official website.
Chinese banks were banned from handling cryptocurrencies in 2013, but the government issued a reminder this year. That reflected official concern cryptocurrency mining and trading might still be going on or the state-run financial system might be indirectly exposed to risks.
Friday's notice complained Bitcoin, Ethereum and other digital currencies disrupt the financial system and are used in money-laundering and other crimes.
“Virtual currency derivative transactions are all illegal financial activities and are strictly prohibited,” the People´s Bank of China said on its website.
Promoters of cryptocurrencies say they allow anonymity and flexibility, but Chinese regulators worry they might weaken the ruling Communist Party´s control over the financial system and say they might help to conceal criminal activity.
The People´s Bank of China is developing an electronic version of the country´s yuan for cashless transactions that can be tracked and controlled by Beijing.
FILE - In this Feb. 9, 2021, file photo, the Bitcoin logo appears on the display screen of a cryptocurrency ATM at the Smoker's Choice store in Salem, N.H. China's central bank on Friday, Sept. 24, 2021, declared all transactions involving Bitcoin and other virtual currencies illegal, stepping up a campaign to block use of unofficial digital money. (AP Photo/Charles Krupa, File)
Twitter rolls out Bitcoin tipping
Twitter Inc (NYSE:TWTR). announced that it will allow its users to tip their favourite content creators using Bitcoin by linking their profiles to Strike, the payments application built on the Bitcoin Lightning Network.To get more news about bitkub, you can visit wikibit.com official website.
The social media company‘s Tips service will initially be rolled out through iOS and then brought to Android devices over the coming weeks, said Twitter’s staff product manager Esther Crawford in a blog post.
The company will allow users to add their Bitcoin address, so they can send and receive cryptocurrency tips.
“We want everyone on Twitter to have access to pathways to get paid. Digital currencies that encourage more people to participate in the economy and help people send each other money across borders and with as little friction as possible – help us get there,” said Crawford.
The addition of Bitcoin to the tipping feature had been expected, as Twitter CEO Jack Dorsey is a strong supporter of the cryptocurrency.
Twitter also plans to add non-fungible token (NFT) verification features to the platform, according to media reports, although no specific timeline has been laid out for the feature.
The feature enables users to track and showcase their NFT ownership on Twitter.
Over the past six months, the use of NFTs as avatars on the platform has exploded and a system for verifying the ownership and provenance of NFTs will probably reinforce the NFT ecosystem more broadly, according to the news website Coindesk.
According to media reports, Twitter is looking into new ways to help users have a safer experience on its platform, such as filtering out certain words to stop abusive language.
“We believe we can continue to incentivize the types of conversations that people want to see,” Crawford said in a briefing with reporters.
Bitcoin Revisits $45K, Why Dips Turn Attractive In Short-term
Bitcoin price started a decent increase above the $43,000 level. BTC remained well bid and it managed to clear the $44,000 resistance level plus the 100 hourly simple moving average.To get more news about BINANCE.JE, you can visit wikibit.com official website.
The price even climbed above the $44,500 level and traded close to the $45,000 level. A high is formed near $44,934 and the price is now correcting lower. There was a break below the $44,500 and $44,400 levels.
An immediate support is near the $44,300 level. There is also a key rising channel forming with support near $44,250 on the hourly chart of the BTC/USD pair. The pair is also well above the 23.6% Fib retracement level of the recent wave from the $39,580 swing low to $44,934 high.
On the upside, an immediate resistance is near the $44,800 level. The first major resistance is near the $45,000 level. A clear break above the $44,800 and $45,000 levels could start another increase. The next major resistance is near the $46,200 zone, above which the price could rise towards the $47,000 resistance.
Dips Limited In BTC？
If bitcoin fails to clear the $45,000 resistance zone, it could start a fresh decline. An immediate support on the downside is near the $44,300 level.
The next major support is near the $44,250 zone and the channel trend line. A downside break below the channel support could lead the price towards the $43,500 support zone or the 100 hourly simple moving average. Any more losses could lead the price towards the 50% Fib retracement level of the recent wave from the $39,580 swing low to $44,934 high at $42,250.
Technical indicators:
Hourly MACD – The MACD is slowly losing pace in the bullish zone.
Hourly RSI (Relative Strength Index) – The RSI for BTC/USD is still above the 50 level.
Major Support Levels – $44,250, followed by $43,500.
Major Resistance Levels – $44,800, $45,000 and $46,200.
SEC was the only regulator not willing to meet with Coinbase: Brian Armstrong
Coinbase CEO Brian Armstrong claims that the U.S. Securities and Exchange Commission (SEC) is the only government branch that is not willing to meet with the firm.To get more news about BINANCE JEX, you can visit wikibit.com official website.
Speaking on Anthony Pomplianos Best Business Show on Sept. 24, Armstrong said that during his visit to Washington after Coinbase went public in April, the SEC was the “only regulator” that refused to meet with him:
“I reached out to the SEC. I tried to get a meeting with them. They told me that they weren't meeting with any crypto companies.”
“I was kind of surprised by that because there are so many different regulators out there. Every single one has been willing to meet with us and every other branch of government,” he added.
Armstrong highlighted his firm‘s issues with the SEC’s approach earlier this month, when he revealed the enforcement body had threatened to sue the firm if it launched a USD coin (USDC) lending program that offered 4% annual yields. Despite other firms already offering similar services, he said the SEC refused to give the green light as they deemed the program to be a security but provided no explanation on how it came to that conclusion.
During the interview with Pomp, the Coinbase CEO noted that the SEC has not changed its tune since then, and said they hadnt even placed a phone call to the firm. Armstrong asked:
“How are they protecting consumers in this case？ I think a lot of consumers demonstrably have wanted to earn higher yields on their savings accounts. They're not really getting those products from the existing financial services.”
“So that was one open question. And then the second one was how are they creating a level playing field？” he added.
Armstrong said Coinbase had considered taking the SEC to court but decided that it was not worth a lengthy legal battle, not least because “there's a lot of deference given to regulators in the court system.”
The firm has now walked back its plans to launch the program, and will instead sit on the sidelines until the regulatory landscape around crypto lending services become more transparent:
“We're going to wait and see what the SEC does in terms of the other products that are out there already in the market where it's not a level playing field today.”
“I think we want to also just focus our efforts on maybe even more important things happening in crypto, like the questions around which of these tokens are securities and how is DeFi going to be used？” he added.
On the subject of how policy makers view crypto, Armstrong said there‘s a 50/50 split in Washington between people who think it’s risky and people who see the opportunity the sector provides:
“You know, 50% of the people I talked to in DC, roughly, they're still thinking of crypto as a risk. They think this is scary. This is dangerous. They have all kinds of misconceptions in their head about the percentage of activity that's for illicit activity.”
“So that's probably half the people I meet in D.C. and the other half, they realize that this is actually a huge opportunity,” he added.
Armstrong also appeared at TechCrunch Disrupt conference on Sept. 22 and revealed that Coinbase is preparing a draft regulatory framework that it will put forward to U.S. lawmakers next month. The firm is hoping to be an “advisor” that can advocate for “sensible regulation”, with Armstrong noting that regulators have asked the firm multiple times for a crypto proposal.