Guide to Buy Metal Wire Detector in NOYAFA

Guide to Buy Metal Wire Detector in NOYAFA

2021-10-23
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The design of metal wire detector can be described as what we call timeless. It is elaborately designed and has an aesthetic streak. There is a timeless quality to the product' performance and it works with strong stability and dependability. SHENZHEN NOYAFA ELECTRONIC CO.,LIMITED has proved to all that the product has met the strictest quality standard and is extremely safe for people to use.NOYAFA has set up brilliant influence locally and globally with our series of products, which is noted for its creativity, practicality, aesthetics. Our deep brand awareness also contributes to our business sustainability. Over the years, our products under this brand have received high praises and wide recognition worldwide. Under the help of talented personnel and our pursuit of high quality, the products under our brand have been sold well. As a service-focused company, Best Cable Tester Supplier in China _ Noyafa attaches great importance to the service quality. To ensure the products including metal wire detector delivered to customers safely and completely, we work with reliable freight forwarders with sincerity and closely follow up the logistics process.
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Best Wire Tracker to Cut, Tame,& Protect Home Wires
Best Wire Tracker to Cut, Tame,& Protect Home Wires
The introduction of wire trackerWire tracker is a robotic and autonomous material handling system that helps to automate the manual process of tying wire bundles. With the help of this machine, wire bundles are automatically wrapped around a bundle wrapping machine to be transported.Wire tracker saves time and manpower by decreasing material handling cost and increasing productivity. It also increases efficiency by automating the manual process of tying wire bundles. This system has many benefits in terms of safety as well as environmental impact.With the introduction of this machine, the automation process improves labor efficiency as well as safety in various applications such as power lines, water lines, solar panels, etc. Wire tracker reduces environmental impact by decreasing fuel consumption and greenhouse gas emissions from forklifts and trucks for transportation purposes.Tips for wire trackerWire trackers are among the most vital part of any electronics assembly or electronics manufacturing. They are responsible for accurately locating and tracking the wires on an electronic device during a production run.Wire tracking is not just about precision and accuracy - it’s also about efficient use of time, so a wire tracker needs to be able to handle multiple tasks at once.In this article, we will highlight some tips for finding the best wire tracking machines for your production facility.For starters, you need to decide what type of wire tracker you want. There are two main types: manual and automatic wire trackers. The former is more precise but it requires more time-consuming set-up while the latter can be adjusted easily from one machine type to another but they require more investments in automation equipmentHow to use wire tracker?Wire trackers are used by wire-tracing artists to work on creating their designs. They use a variety of tools such as wire, pens, paper and cardboard to create artworks.The process is similar to crocheting or weaving one fiber at a time. The artist has to form the wire into different shapes and coils. To start working with the wire, the artist needs to take it out of its packaging and unravel it from its plastic casing. This process is done by pulling it through one’s fingers and wrapping it around the hand until it forms a coil that they can continue working on.The specifications of wire trackerWire trackers are a tool used in the wire trade to ensure that items are accurately transported and separated. They work by allowing items to pass through a narrow slot without getting stuck.Wire trackers come in various shapes and sizes, but all of them are made from steel with a smooth-walled interior. The surface of them is not very rough, which makes it difficult to hook or grab the item by mistake.Wire trackers have many uses across the different industries. They can be found at airports, factories, warehouses, shopping malls, libraries and other places where valuable goods need safe transport.The product instructions of wire trackerWire trackers are the most widely used DIY tool in home improvement projects. They are used to hold wires, pipes, and cables.The instructions for using wire trackers are simple - however there is still an overwhelming number of problems that people have with them. It is important for manufacturers to make sure that their product instructions are easy to understand and don't include any spelling mistakes or grammatical mistakes.This section discusses how product instructions can be improved by AI writing assistants so that they can become more effective in improving the user experience.The application of wire trackerWire tracking is the process by which a wire is used to measure the progress of a drill.Wire tracking systems enable drill operators to easily and quickly set up their own equipment and work, keeping them safe. It also ensures greater efficiency and accuracy with each drilling job.Wire tracking allows for an increased level of control over drilling operations, which makes it perfect for high-quality production jobs where quality control is important
Best Cable Tester& Cable Tester Software
Best Cable Tester& Cable Tester Software
This article will help you find the best cable tester for your needs.A good cable tester is more than just a cable tester. It should be able to give a sufficient overview of the cable connections and be able to identify any problems with the connection.There are many different types of cable testers and they all do the same thing.In the cable industry, there is a need to test different cables, both for the purpose of quality assurance and in order to make sure that a certain product is compatible with different types of equipment.There are several software products available for testing cable, especially as they become more common in homes and businesses. Some of them have been designed specifically for testing cables. But the problem is that most of them require you to install it on your own computer or laptop first before you can use it. Some are hard to use and require too many settings so that you have to go through many options before finding an appropriate setting.This article will guide you through some tips on installing any cable tester properly so that you can quickly get your cable tested without having to do much research. It will also point out someWe have a cable tester, a type of cable plug that is used to ensure the quality of cables. The cable tester has four prongs and is connected to the main power supply by one wire. These wires are also connected in pairs: one goes to the positive terminal and another goes to the negative terminal. When you want to connect two wires together, you need to connect them first in pairs (with positive and negative terminals) and then separately in pairs (with positive and negative terminals) as shown below:In order for you to test whether or not two cables are connected properly, you will need a cable tester socket adapter. This device looks like an ordinary socket with only one wire on it. The connection between these two wires is made with an adapter. You can find theseIn order to make sure you get the best deals on TVs, Blu-ray players, etc., you need to do some research. You might have heard about a TV review site named "BestBuy" or a "Best Buy". You might also have found yourself going there to check out the latest offers only to be disappointed when your search didn't turn up anything interesting.As you've probably come to realize, there are a lot of possibilities when it comes to finding the best deals on TVs, Blu-ray players and other gadgets. But even if it is easier than ever before, there is still so much information that you need in order for these tradesmen and women to be able to offer quality recommendations.Best cable tester ensures that cables are properly connected to all the devices.With accurate, fast and reliable cable testers, you can easily save your business money.The cable tester software is an essential tool for any cable equipment buyer. It helps to assess the quality of a cable, measuring it's resistance and voltage.Cable testers have been in use since the 50's. The need for them is now less, but they are still widely used in the market.The best cable testers can help you to test Ethernet cables, power cables, phone wires and other wired connections. They also include various other inputs and outputs from home appliances like refrigerators, washing machines and dishwashers.The best cable testers can also be used in different situations to find out whether your device is working properly or not. If your computer isn't functioning properly, you should check the cable of it first before taking any action on it immediately to make sure that there are no faulty connections or miswired devices present in the system because of which your computer won't work properly at all. On the other hand if something goes wrong with a certain deviceToday's cable tester software/hardware is very sophisticated and works in a particular niche. This makes it a perfect fit for cable testers who are looking for precise information such as the channel number, the length of the cable and the condition of the cable.While there may be other software that can do these tasks, this software provides them quite well. This is why you should consider purchasing this software to get some competitive edge in your field.
How to Ensure the Correctness of Cable Identification by Live Cable Identification Instrument
How to Ensure the Correctness of Cable Identification by Live Cable Identification Instrument
In the 21st century, with the rapid development of railway, the speed per hour is faster and faster, and the marshalling operation is more and more intensive, it is necessary to ensure the normal operation of electrical service system. How to ensure the correctness of cable identification by live cable identification instrument, we will discuss and explain this problem below. In the electrical service support, the fault and construction of signal cable shall be tested and identified quickly. If the identification is wrong, it will have a very serious impact and cause train accidents. So let's talk about the identification of electrical service system. 1、 Current situation and disadvantages of signal cable identification in telecommunication system target cable identification is required in field work such as emergency repair, relocation and replacement of signal cable. Since there is no suitable instrument, most of our signal cable maintainers use the following methods to identify. First, wait for the skylight point, and remove the signal cable sheath when the skylight point; Secondly, two core wires are selected as the identification wire, and the two core wires are also found at the end; Finally, use the blade to cut the skin of the selected two core wires for short connection, and use the external meter to measure whether the selected two core wires are short circuited at the end. If they are short circuited, it means that the identification is accurate, otherwise, the identification is wrong. However, there are many disadvantages in using this method for identification: 1. Generally, such work is rush repair, which must be completed in the skylight point. If it takes up the time in the skylight point for identification, the rush repair time will be greatly reduced, and some even need to apply for two skylight points to complete a work; 2. After the selected two core wires are short circuited, the two core wires found at the end may not correspond, resulting in wrong results; 3. The outer skin and copper shield of the cable shall be broken. After identification, this place shall be restored. In the future, this place is a joint and a potential fault point. 4. The most important thing is that this identification often produces wrong results, resulting in operation accidents. 2、 Current status of cable recognizer 1. Current status of identification equipment (identification and attached identification): status of identification 1: conventional cable recognizer is designed for power cable identification and is widely used in the power field. Whether imported or domestic, it has two service conditions: 1) it has high requirements for the loop resistance of the target cable, Generally, it shall not exceed 50 ohms. If it exceeds the range of this circuit resistance, the equipment will not work normally, which is beyond the range of equipment use; 2) Disconnect at least one end of the outer armor grounding (same as shielding grounding) at both ends of the target cable, so that the applied signal cannot return from the target cable. Therefore, this power cable identification instrument is not suitable for the identification of electrical signal cables. Identification status II. When promoting digital path tester, some manufacturers publicize that the equipment has identification function. In fact, when using the digital path tester to identify, if the receiver touches the identified cable, which signal is the strongest, that is the identified cable. This recognition method has a single judgment basis in recognition, only the signal size, no signal direction, and can not be used as the final judgment. Moreover, such equipment has great attenuation on the signal cable, and the identification of long-distance signal cable can not be done at all. 2. Conclusion: the use conditions of power cable identification instrument and digital path tester determine that these two types of equipment are not applicable to the signal cable of electrical service system. 1) For the signal cable of electric service. The cable is very long, with a length of more than 5km, and some can reach more than 20km; The wire core is very thin, generally 1mm ² , The resistance is 23.5 Ω per kilometer, and the cable body resistance of more than two kilometers has reached the critical value of equipment test, so the loop resistance problem has become a hard wound of the conventional identification instrument. 2) In the electrical service system, it is very inconvenient to open the outer armor grounding (the same as shielding grounding) of the signal cable. The regulations of each Railway Bureau and railway line are inconsistent. Some cannot be opened, some must be opened in the skylight point, and must be restored before the end of the skylight point. Based on the above two points, the conventional cable identifier and Pathfinder can not meet the requirements of signal cable identification of railway electrical service system. 3、 During the test of railway signaling cable identifier, the requirements for loop resistance can reach 1000 Ω, and there is no requirement for armored grounding or ungrounded of the target cable. The utility model solves the difficult problem of identifying the signaling cable. The railway communication cable is specially designed and can be used online. It has the characteristics of micro power transmitting signal, has no crosstalk and interference to the data transmission of adjacent cables, and accurately finds out the required cable. The size double jaw configuration can not only identify the cable, but also identify the wire pair in the cable. Color large screen LCD, live voice prompt, friendly intelligent man-machine interface, and its unique intelligent orientation can indicate the signal direction, which makes the operation simple and practical. It is especially suitable for field use. Even untrained personnel can use it quickly. Through live measurement, it is not necessary to apply for night skylight time to cut off and repair cables. Workers in the front-line electrical service workshop can measure during the day, including when high-speed rail / Bullet train passes, which improves the timeliness and operability of detection.
Characteristics of Live Cable Identification Instrument
Characteristics of Live Cable Identification Instrument
Live cable identification instrument is of great significance in cable construction and maintenance. The charged cable identification instrument uses single chip microcomputer technology to encode the transmitted signal at the transmitting end, drives the large-diameter caliper to transmit the large current phase coded signal with an average value of 0. The single chip microcomputer in the receiver decodes and identifies the received phase coded signal. According to the uniqueness of the signal phase characteristics on the target cable, the target cable is identified from a large bundle of other cables. The live cable identification instrument can also directly connect the output signal to the cable in power failure operation. At this time, the grounding circuit can be identified to be more than 1000 ohms. It is a light, compact and portable instrument. It is suitable for various types of high and low voltage power cables. The instrument is composed of current pulse transmitter, receiver, transceiver caliper and several connecting wires. It has high-power current pulse output; The on-site received signal has clear characteristics, easy to carry, light and flexible, high sensitivity, can effectively suppress the on-site power frequency interference, and judge accurately and quickly; The protection circuit is reliable and not afraid of output short circuit; Large jaw Ñ„ 150 power cables suitable for various cross-sectional areas; There is a high-power isolation transformer inside, and there is no direct electrical contact between the operator and the mains. However, it is not allowed to touch the black and red clamp wires with hands when the instrument is charged. Dear customers: Hello, our company is a high-quality development group with strong technical force, providing users with high-quality products, complete solutions and superior technical services. The main products are cable fault tester, street lamp cable fault tester, underground pipeline detector, etc. The enterprise adheres to the tenet of building a business in good faith, keeping the business with quality and developing the business with enterprising. It continues to climb new peaks with a firmer pace and make contributions to the national automation industry. New and old customers are welcome to buy their favorite products at ease. We will serve you wholeheartedly!
The Optical Fiber Connector
The Optical Fiber Connector
A fiber optic connector is a detachable (active) connection between an optical fiber and an optical fiber. The two end faces of the optical fiber are precisely butted together so that the optical energy output from the transmitting optical fiber can be coupled to the receiving optical fiber to the maximum extent. It also minimizes the impact on the system due to its involvement in the optical link, which is a basic requirement for fiber optic connectors. To some extent, fiber optic connectors affect the reliability and performance of optical transmission systems.Basic introductionA connecting device for re-plugging between optical fibers, also called a fiber optic movable joint. The main performance parameters (and typical values) are: insertion loss ( 5dB), plug-and-repeat repeatability and interchangeability between connectors (500 changes). When used in a large-capacity high-speed transmission system, reflection is also required to be small.IntroductionOptical fiber connectors can be divided into single-mode and multi-mode connectors of common silicon-based fibers according to different transmission media, and other fiber-optic connectors such as plastics; the structure of the connector can be divided into: FC , SC, ST, LC, D4, DIN, MU, MT, etc. Among them, ST connectors are usually used for wiring equipment terminals, such as fiber distribution frames, fiber modules, etc.; and SC and MT connectors are usually used for network equipment terminals. According to the shape of the end face of the fiber, there are FC, PC (including SPC or UPC) and APC; according to the number of cores of the fiber, there are also single core and multi-core (such as MT-RJ). Fiber optic connectors are used in a wide variety of applications. In the actual application process, we generally distinguish according to the structure of the fiber optic connector. Here are some common fiber connectors:FC type fiber optic connector This connector was first developed by NTT Japan. FC is an abbreviation of Ferrule Connector, which indicates that the external reinforcement method is a metal sleeve and the fastening method is a turnbuckle. At the earliest, FC type connectors, the mating end faces of the ceramic pins used were planar contact (FC). The connector has the advantages of simple structure, convenient operation and easy manufacture, but the fiber end face is sensitive to fine dust, and Fresnel reflection is easy to occur, and it is difficult to improve the return loss performance. Later, this type of connector was improved by using a pin (PC) with a spherical end face, and the external structure was not changed, so that the insertion loss and return loss performance were greatly improved.SC type fiber optic connector This is a fiber optic connector developed by NTT Corporation of Japan. The outer casing has a rectangular shape, and the structure of the pin and the coupling sleeve is exactly the same as that of the FC type. The end face of the pin is mostly made of PC or APC type; the fastening method is a plug-and-pin type, which is not required. Rotate. Such connectors are inexpensive, easy to insert and remove, have small fluctuations in insertion loss, high compressive strength, and high installation density.The ST and SC interfaces are two types of fiber connectors. For 10Base-F connections, the connectors are usually ST type. For 100Base-FX, the connectors are mostly SC type. The core of the ST connector is exposed and the core of the SC connector is inside the connector. Biconic Connector The most representative of these types of fiber optic connectors was developed by Bell Laboratories of the United States. It consists of two precision-molded ends with frusto-conical cylindrical plugs and a double-conical plastic sleeve inside. The coupling assembly of the barrel.DIN47256 fiber optic connector This is a connector developed by Germany. The connector and coupling sleeve of this type of connector have the same structural dimensions as the FC type, and the end face treatment adopts PC grinding. Compared with the FC type connector, the structure is more complicated, and the internal metal structure has a spring that controls the pressure, so as to avoid damage to the end surface due to excessive insertion pressure. In addition, the mechanical accuracy of such a connector is high, and the value of the insertion loss is small. MT-RJ type connector MT-RJ started with the MT connector developed by NTT, with the same latching mechanism as the RJ-45 LAN electrical connector. The optical fiber is aligned with the guide pin mounted on both sides of the small sleeve for easy transmission and reception. The machine is connected, and the connector end face fiber is a double-core (interval 0. 75mm) arrangement design, which is the next-generation high-density optical connector mainly used for data transmission.LC connector The LC connector was developed by the famous Bell Institute and is manufactured using a convenient modular jack (RJ) latch mechanism. The size of the pins and sleeves used is half that of ordinary SC, FC, etc. , which is 1. 25 mm. This can increase the density of the fiber optic connectors in the optical distribution frame. At present, in the single-mode SFF, the LC type connector has actually occupied a dominant position, and the application in multi-mode has also grown rapidly.MU type connector The MU (Miniature Unit Coupling) connector is the worlds smallest single-core fiber optic connector developed by NTT based on the most widely used SC-type connector. The connector uses a 1. 25mm diameter bushing and self-retaining. The advantage of the organization is that it enables high-density installation. With MUs l.25mm diameter bushings, NTT has developed a series of MU connectors. They have socket type optical connectors (MU-A series) for fiber optic cable connection, backplane connectors with self-holding mechanism (MU-B series), and simplified sockets for connecting LD/PD modules and plugs (MU-SR series) )Wait. With the rapid development of fiber-optic networks to larger bandwidths and larger capacity and the widespread use of DWDM technology, the demand for MU-type connectors will also grow rapidly.MC connectorIn 2012, the domestic communication company independently developed a smaller and denser MC connector than the LC connector. The Nippon MC Fiber Optic Active Connector is a high-density single-core fiber optic connector for high-density applications such as high-capacity central rooms and high-density data centers. The MC fiber optic connector has a high density and can double the LC connector in the same space, making it the worlds smallest and densest connector.The main parameters:General structureThe main purpose of fiber optic connectors is to achieve fiber optic connections. Optical fiber connectors that have been widely used in optical fiber communication systems are numerous in variety and structure. However, the basic structure of various types of fiber optic connectors is consistent, that is, most fiber optic connectors are generally made of high-precision components (composed of two pins and one coupling tube). Alignment of the fiber.In this method, the fiber is inserted into and fixed in the pin, and the surface of the pin is polished to achieve alignment in the coupling tube. The outer components of the pins are made of metal or non-metal materials. The butt end of the pin must be ground and the other end typically uses a bend limiting member to support the fiber or fiber optic cable to relieve stress. The coupling tube is generally made of two semi-synthetic, fastened cylindrical members made of ceramic, or bronze, and is equipped with a metal or plastic flange to facilitate the mounting and fixing of the connector. In order to align the fiber as precisely as possible, the processing precision of the pin and the coupling tube is very high. PerformanceThe performance of fiber optic connectors, first of all, optical performance, in addition to the interchangeability, repeatability, tensile strength, temperature and number of insertions and removals of fiber optic connectors.(1) Optical performance: For the optical performance requirements of the optical fiber connector, the two most basic parameters of insertion loss and return loss are mainly used.Insertion loss (InsertionLoss) is the loss of the effective optical power of the link caused by the introduction of the connector. The smaller the insertion loss, the better. Generally, the requirement should be no more than 0.5dB.ReturnLoss (ReflectionLoss) refers to the ability of the connector to suppress the reflection of the link optical power, and its typical value should be no less than 25dB. In the practical application of the connector, the surface of the pin has been specially polished to make the return loss larger, generally not less than 45dB.(2) Interchangeability and repeatabilityThe fiber optic connector is a universal passive device. For the same type of fiber optic connector, it can be used in any combination and can be used repeatedly. Therefore, the additional loss introduced is generally less than 0.2 dB.(3) Tensile strengthFor a good fiber optic connector, the tensile strength is generally required to be no less than 90N.(4) TemperatureGenerally, fiber optic connectors must be able to operate at temperatures between -40oC and 70oC. (5) Number of insertions and removalsThe fiber optic connectors used can be plugged and unplugged more than 1000 times.Connection step1. The Fiber Optic Quick Connector is an innovative field termination connector that includes factory pre-installed fiber, pre-cast ceramic ferrules, and a mechanical splice mechanism.2. When the termination is completed, only the introduction fiber or the indoor fiber can be inserted into the mechanical connection mechanism, without using other tools, the termination process takes only about 2 minutes, which greatly saves the installation time. 3. The ferrule and end face of the fiber optic quick connector are pre-ground and pre-polished at the factory, and the mechanical connection mechanism is located at the end of the ferrule to fix the inserted fiber.4. The mechanical connection mechanism is mainly composed of a V-shaped groove and a clamping element; when a fiber needs to be inserted, the V-shaped groove is opened by a wedge-shaped clamp to facilitate the smooth insertion of the optical fiber.5. When the fiber is inserted into the V-groove and fixed, remove the wedge clamp from the V-groove. In order to facilitate users to better understand and select fiber optic connectors, Konnra Electronics hereby organizes the knowledge and classification of fiber optic connectors, and hopes to be helpful to the majority of users RELATED QUESTION Do I have to acquire some type of license to sell medical equipment on an e-commerce site? You need narrow down u201cmedical equipmentu201d its just to general, you have x-ray, mri, ultrasound, c-arms, laboratory, surgical equipment, sterilizing, furniture, ICU, patient monitoring, anaesthesia etc. to say some but the list goes on and onRegardless of the ecommerce site or a website of your own the u201cregulationu201d part comes mostly around your product and your operations;About the products:Will the equipment be new or used?Which country manufactures the product?Who and how are you importing or buying the equipment?FDA clearance is a must for the US market, many europe countries (if not all) ask for CE certificate as a must to enter the country, ISO for manufacture is optional but desireable.About your operations:Are you legally constituted?Does your federal or local government require special permits for healthcare business?Do your products imply any additional risks such as gamma expossure or x-ray?Shipping your products require special handling or additional permits?Hope it helps, for specific questions Iu00b4d be happy to answer through however quora allows you to contact me have a nice day!Do I have to acquire some type of license to sell medical equipment on an e-commerce site?.
Introduction of Test Composition of Live Cable Fault Tester
Introduction of Test Composition of Live Cable Fault Tester
Cable fault tester is a commonly used cable fault detection equipment. This equipment is used with a variety of cable fault detection. Its stable performance and accurate detection make the cable fault detection more comprehensive. The work efficiency of inspectors has been greatly improved. Today we mainly explore the composition of live cable fault tester. Test composition of live cable fault tester: 1. Live cable fault tester is composed of the following parts: 1. Instrument host: cable fault flashover tester, referred to as flashover tester for short. Cable path test signal source, referred to as path tester. Cable fault point / path meter receiver, referred to as point meter. 2. High voltage accessories: high voltage pulse capacitor. The utility model relates to an AC / DC dual-purpose high-voltage test transformer. High voltage test transformer operation box. 2、 The test functions of the cable fault tester mainly include: 1. Purpose: it is suitable for low resistance fault test, short circuit fault test, open circuit fault test, high resistance leakage fault test and high resistance flashover fault test of various power cables with different sections and media, high frequency coaxial cables, municipal cables, street lamp cables, ground buried wires, etc. Specifically, there are the following types: (1) testable cables are equivalent according to voltage: low voltage cables and high voltage cables. (2) Testable cables can be divided into: power transmission cables; Control cable; Street lamp cable. (3) The testable cables can be divided into: directly buried cables, cables laid in cable trenches, overhead cables and more than two parallel directly buried low-voltage wires. (4) Testable cables can be divided into: short circuit fault; Phase failure; Low resistance fault; High resistance leakage fault; High resistance flashover fault is described in detail after fault classification. (5) If there is a cable identifier, we can find the cable we are looking for from multiple cables buried in the cable trench, that is, the cable identifier. (6) Both fault test and cable identification are conducted for power-off cables, and fault test cannot be conducted for live running cables. 3、 Introduction to the test principle of cable fault tester: 1. The host of this set of instrument is a host, which is mainly used for cable fault test. 2. It is a rough measuring instrument for cable fault distance, which can measure the approximate distance from the fault point to the cable test end face. 3. The lightning meter can measure the cable length and the propagation velocity of electromagnetic wave in the cable. The test principle of lightning meter is radar reflection method, also known as pulse reflection method. Single end test distance of lightning meter: 15km. Minimum test distance (blind area) of lightning meter: 15-20m. 4. Measurement error of cable fault tester: rough measurement error & plusmn; 1%, system (point) error & plusmn; 0.2m. In short, after accurately determining the fault point, dig a pit to find the fault point. 5. The principle of cable fault detector for finding cable path is to add electromagnetic wave signal to the tested cable and receive the signal of finding cable path through the pointing instrument. The minimum characteristic of receiving electromagnetic signal on the ground directly above the cable is used to determine the buried position of the cable.
How to Better Find the Fault of Buried Cables in Rural Areas
How to Better Find the Fault of Buried Cables in Rural Areas
In the transformation of China's agricultural network, buried lines have been adopted in many areas. Although PVC insulated plastic wire has many advantages, such as good chemical stability, no occupation of farmland, safe operation and reduction of line loss, after long-term use, due to various reasons, the fault phenomenon of buried wire is gradually increasing. Let's take a look at how to carry out the fault finding of buried cables in rural areas. Methods and characteristics of fault finding and detection of buried cables in rural areas. 1. Analysis and judgment method for the fault of buried line, generally, we should first understand the relevant situation of the fault, then conduct comprehensive analysis, find out the cause of the fault, and then find and eliminate it pertinently. For example, finding informed parties, such as construction workers, wire users, and other relevant personnel to understand the situation in detail, can often eliminate the fault in the shortest time and at less cost. It has the advantages of simple operation, no need for complex instruments, and can eliminate some faults in time. This method is generally not used alone, but in combination with other instrument detection methods. 2. In recent years, the intelligent cable fault tester is widely used to detect the fault buried wire. Therefore, many electricians and maintenance personnel are not familiar with the fault finding and detection methods of rural buried cables. In case of underground pipeline failure, if there is no advanced detection equipment and good detection means, the failure can often not be eliminated within the service period promised by the power supply enterprise, which not only delays time and wastes manpower, but also affects the image of power users and frustrates the enthusiasm of farmers to transform the rural power network. Therefore, rural land buried lines need more specialization. More efficient fault detection equipment. 3. Compared with buried wires, buried power cables have been used in China for decades. The buried cable fault tester has developed from resistance bridge, capacitance bridge and standing wave test to flashover test. The development of the instrument has experienced the ordinary oscilloscope tube display flash lamp and the storage oscilloscope tube display flash lamp. At present, the intelligent instrument has been developed. The instrument adopts new technologies and processes such as large-scale integrated circuit, computer processing technology and large screen LCD. The power cable tester is used to transform it and detect the buried line fault. The effect is good and the efficiency is high. After a lot of practice, the detection of a buried line fault generally does not exceed 30 minutes from the beginning to the end, and the accuracy is very high.
Three Common Methods for OTDR Optical Fiber Testing
Three Common Methods for OTDR Optical Fiber Testing
Optical fiber communication is a communication mode with optical wave as carrier and optical fiber as transmission medium. Optical fiber communication has become the main means of information transmission and the cornerstone of "information highway" because of its long transmission distance, large information capacity and high communication quality. Optical fiber testing technology is the most extensive and basic special technology in the field of optical fiber applications. OTDR is the main instrument in the field of optical fiber testing technology. It is widely used in the maintenance and construction of optical fiber lines. It can measure the length of optical fiber, transmission attenuation of optical fiber, joint attenuation and fault location. OTDR has the advantages of short test time, fast test speed and high test accuracy.1. Two basic formulas supporting OTDR TechnologyOTDR (optical time domain reflectometer) is a high-tech and high-precision photoelectric integrated instrument made by using Rayleigh scattering and Fresnel reflection when optical pulse is transmitted in optical fiber. The semiconductor light source (LED or LD) outputs light pulses modulated by the driving circuit, which are injected into the tested optical cable line through the directional optical coupler and movable connector to become incident light pulses.When the incident light pulse is transmitted in the line, Rayleigh scattered light and Fresnel reflected light will be generated along the way. Most of the Rayleigh scattered light will be refracted into the cladding and attenuated. The back Rayleigh scattered light opposite to the propagation direction of the light pulse will be transmitted to the light inlet port of the line along the optical fiber, and will be transmitted to the photodetector through directional coupling shunt and converted into electrical signals, After low-noise amplification and digital averaging, the processed electrical signal is scanned synchronously with the trigger signal emitted from the back of the light source and becomes a reflected light pulse on the oscilloscope.The returned useful information is measured by the OTDR detector, and they are regarded as time or curve segments at different positions in the measured optical fiber. According to the time from transmitting signal to returning signal, and then determine the speed of light in quartz material, the distance (fiber length) l (unit: m) can be calculated, as shown in formula (1).In formula (1), n is the average refractive index and â–³ t is the transmission delay. The attenuation a (unit: dB / km) can be calculated by using the power level corresponding to the incident light pulse and the reflected light pulse and the length of the measured optical fiber, as shown in formula (2):2. Five parameter settings to ensure OTDR accuracy2.1 test wavelength selectionSince OTDR serves optical fiber communication, the test wavelength shall be selected before optical fiber test, and only 1310 nm or 1550 nm shall be selected for single-mode optical fiber. Since the influence of 1550 nm wavelength on the bending loss of optical fiber is much more sensitive than 1310 nm wavelength, 1550 nm wavelength is generally used to test the whole process optical fiber backscattering signal curve of an optical cable or an optical fiber transmission link, whether it is optical cable line construction, optical cable line maintenance or experiment and teaching.The shapes of the test curves at 1310nm and 1550nm are the same, and the measured fiber connector loss values are basically the same. If no problem is found in the 1550 nm wavelength test, the 1310 nm wavelength test is certainly no problem.If the 1550 nm wavelength is selected for testing, it is easy to find out whether there is excessive bending in the whole process of the optical fiber. If a large loss step is found somewhere on the curve, retest with 1310 nm wavelength. If the loss step disappears at 1310 nm wavelength, it indicates that there is excessive bending at this place, which needs to be further found and eliminated. If the loss step is also large at 1310 nm wavelength, there may be other problems in the optical fiber, which need to be found and eliminated. In the test of single-mode optical fiber line, 1550 nm wavelength should be selected as far as possible, so the test effect will be better.2.2 optical fiber refractive index selectionThe refractive index of the single-mode optical fiber used now is basically in the range of 1.4600 1.4800, which should be accurately selected according to the actual value provided by the optical cable or optical fiber manufacturer. For G.652 single-mode fiber, if 1310 nm wavelength is used in actual test, the refractive index is generally 1.4680; If 1550 nm wavelength is used, the refractive index is generally 1.468 5. Incorrect selection of refractive index will affect the test length.In equation (1), if the refractive index error is 0.001, an error of about 35 m will be generated in the relay section of 50000 M. Small mistakes in optical cable maintenance and troubleshooting will bring obvious errors, which must be paid enough attention during testing.2.3 selection of test pulse widthIf the set light pulse width is too wide, strong Fresnel reflection will be generated, which will increase the blind area. Although the narrow test light pulse has a small blind area, the test light pulse is too narrow, the power must be too weak, the corresponding backscattering signal is also weak, the backscattering signal curve will fluctuate, and the test error is large. The set optical pulse width shall not only ensure that there is no strong blind spot effect, but also ensure that the backscattering signal curve has sufficient resolution and can see each point along the optical fiber.Generally, an appropriate test pulse width is selected according to the length of the measured optical fiber, and an optimal value is determined after one or two trials. When the distance of the measured optical fiber is short (less than 5000 m), the blind area can be less than 10 m; When the distance of the measured optical fiber is long (less than 50000 m), the blind area can be less than 200 m; When the distance of the measured optical fiber is very long (less than 2500 000 m), the blind area can be up to more than 2000 m.In the single disk test, the blind area can be less than 10 m by properly selecting the optical pulse width (50 nm). If the average value is obtained through two-way test or multiple tests, the impact of blind area will be less.2.4 selection of test rangeThe range of OTDR refers to the maximum distance that the abscissa of OTDR can reach. During the test, the measuring range shall be selected according to the length of the measured optical fiber, and it is better that the measuring range is 1.5 times the length of the measured optical fiber. If the range selection is too small, it can not be seen comprehensively on the display screen of the optical time domain reflectometer; When the range selection is too large, the abscissa compression on the display screen of the optical time domain reflectometer can not be seen clearly.According to the practical experience of engineers and technicians, the selection of test range can make the backscatter curve account for about 70% of the OTDR display screen, whether it is length test or loss test, better direct viewing effect and accurate test results can be obtained.In the test of optical fiber communication system, the link length is hundreds to thousands of kilometers, the relay section length is 40 60 km, and the single optical cable length is 2 4km. Good test results can be obtained by selecting the range of OTDR.2.5 selection of averaging timeBecause the backscattered light signal is extremely weak, the method of multiple statistical average is generally used to improve the signal-to-noise ratio. OTDR test curve samples the reflected signal after each output pulse, and averages the multiple samples to eliminate random events. The longer the averaging time is, the closer the noise level is to the minimum value, and the larger the dynamic range is. The dynamic range obtained with an average time of 3 min is 0.8 dB higher than that obtained with an average time of 1 min.Generally speaking, the longer the averaging time, the higher the test accuracy. In order to improve the test speed and shorten the overall test time, the test time can be selected within 0.5 3 min.In the connection test of optical fiber communication, satisfactory results can be obtained by selecting 1.5 min (90 s).3 three common methods of OTDR testingWhen OTDR tests optical cables and optical fibers, the test occasions include factory test of optical cables and optical fibers, construction test of optical cables and optical fibers, maintenance test and regular test of optical cables and optical fibers. The test connection of OTDR is shown in Figure 1.The test connection method is: OTDR - optical fiber connector - the first optical cable - the second optical cable - the nth optical cable, and the terminal is not connected to any equipment. According to the actual test work, there are three main methods:3.1 OTDR backward test methodThis method is mainly used to monitor the optical cable connection. The optical cable connection must be equipped with a special optical fiber fusion machine and optical time domain reflectometer (OTDR). After welding a fiber core, the welding machine will generally give the estimated attenuation value of this contact. This method of testing has three advantages:(1) OTDR is fixed, omitting the vehicles and a lot of manpower and material resources required for instrument transfer;(2) The test point is selected in the place where there is mains power without gasoline generator;(3) The test points are fixed to reduce the stripping of optical cables.At the same time, this method also has two disadvantages:(1) Due to distance and terrain constraints, it is sometimes impossible to ensure smooth communication;(2) With the continuous increase of connection distance, the test range and accuracy of OTDR are limited.At present, there are generally three methods to solve these problems:â‘ The use of mobile phones in the city and suburbs can keep the testers and successors in touch at any time, facilitate organization and coordination, and improve work efficiency.â‘¡ Contact by telephone. Make sure to connect one optical fiber (such as blue optical fiber unit and red optical fiber) to the optical telephone as the connecting line. Of course, the last optical fiber used for communication cannot be monitored because it cannot be contacted during fusion and fiber winding. Even so, the possibility of problems will be greatly reduced (if it is a 24 core optical cable, the probability of problems will be reduced to less than 1 / 24 of the original).â‘¢ When the optical cable connection reaches a relay distance, the OTDR moves forward.The test practice shows that these monitoring methods are effective to ensure quality and reduce rework.3.2 OTDR forward one-way test methodOTDR is tested at the first joint point in the optical fiber connection direction, and construction vehicles are used to transfer the test instruments and testers in advance. Using this method for monitoring, the test point and connection point always have only one disc of optical cable length, the attenuation accuracy of the test joint is high, and it is convenient for communication. At present, the length of one optical cable is about 2 3 km. In general terrain, communication can be ensured by using walkie talkie. If the optical cable has a corrugated steel strip protective layer, you can also use the magnet telephone to contact.The disadvantages of this test method are also obvious. Moving OTDR to each test point is labor-consuming and time-consuming, which is not conducive to the protection of instruments; The test points are also limited by the terrain, especially when the line is far away from the highway and the terrain is complex. Portable OTDR is selected for monitoring. The short-range test does not require high dynamic range of the instrument, and the small 0tdr has small volume, light weight and convenient movement, which can greatly reduce the workload of testers and improve the test speed and work efficiency.3.3 OTDR forward two-way test methodThe OTDR position is still the same as the "forward one-way" monitoring, but two optical fibers are respectively short circuited at the beginning of the connection direction to form a loop. This method can not only meet the optical fiber test of relay section, but also monitor the optical fiber connection. When testing the optical fiber in the relay section, the incident light pulse, reflected light pulse, joint point, fracture point, fault point and attenuation distribution curve can be clearly seen on the display screen of the optical time domain reflectometer. The OTDR test event type and display are shown in Figure 2, which can provide convenience for optical cable maintenance.When monitoring optical fiber connection, due to the increase of loopback point, the bidirectional value of connection loss can be measured on OTDR. The advantage of this method is that it can accurately evaluate the quality of the joint.Due to the test principle and optical fiber structure, there will be false gain and false large attenuation in one-way monitoring with OTDR. For an optical fiber connector, the mathematical average of attenuation values in two directions can accurately reflect its real attenuation value. For example, the attenuation of a connector measured from a to B is 0.16 dB, and that measured from B to a is -0.12 dB. In fact, the attenuation of this connector is [0.16 (- 0.12)] / 2 = 0.02 dB.4 ConclusionAs the main instrument of optical fiber communication,
Introduction to the Use of Cable Fault Finder
Introduction to the Use of Cable Fault Finder
Due to the cable fault caused by cable laying, the location of cable fault varies with the cable laying mode, and the location increases gradually. Among them, the laying side in bridges, tunnels and trenches is relatively simple, and the direct burial method is difficult to locate. When the nature of the fault is simple, a special cable fault finder is used, and it takes 4-5 days or even longer to locate the equipment within dozens of minutes. When using echo method to locate cable fault, sometimes by transferring fault phase and wiring mode, complex fault will often be transformed into simple fault to quickly determine fault location. It is of great significance for the power supply user department to win time for the emergency repair of on-site lines. Low voltage power cables are generally multi-core cables. When faults occur in continuous use after laying, they generally show two core and multi-core phase to phase or phase to ground short circuit faults. Sometimes when it is detected that the fault waveform collected by one core is not ideal, it can be considered to convert the wiring to other fault cores for fault waveform detection, which often has unexpected effects, The collected and detected waveforms will become more typical and regular, so the specific location of cable fault point can be determined quickly. During the long-term on-site measurement of cable customers, it is found that the fault of small section copper core directly buried power cable (35mm2 and below) and aluminum core cable may be accompanied by short circuit and wire breakage at the same time. During on-site detection, converting short-circuit fault into broken line fault measurement according to the different fault nature of each fault core will often double everything with half the effort. For the medium voltage direct buried power cable with extruded armor as the inner lining, the fault is mostly caused by external mechanical damage. When the insulation core fails, the inner lining may have been damaged. When the cable insulation fault is special and it is difficult to collect the waveform with a professional cable fault tester, the acoustic method can be considered, When the high voltage pulse is directly applied between the steel strip and copper shielding layer of the cable, it will often be fixed quickly. Using the cable fault finder in the field measurement process, we also found that when using the acoustic method to locate the fault of low-voltage cable. When the high-voltage line and ground wire are connected between the bad phase and the metal shield or armor, due to the low resistance metal connection state of the insulation resistance of the two, the sound is very small, so the probe can not be used to listen to the fixed point, and the effect is not ideal. Through the actual listening side on the site for many times, it is found that the distance between the discharge ball gaps is appropriately increased. At the same time, if the high voltage and grounding wire are connected between the two faulty phases, the discharge sound will become louder and the fault point will be determined quickly.
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