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Measuring OD

Measuring calipers have been around for nearly 150 years. In that time they have evolved into full-featured digital measuring systems. But it is a testament to the simplicity and versatility of the original design that the evolution has been so slow and that so few changes have been required to produce the instruments we are familiar with today.

Here are some of the highpoints of the caliper’s evolution since it was introduced in the 1860s:

• In 1899 a second pair of jaws was added, allowing inside as well as outside measurement.
• In 1951 the Vernier scale was recessed for better protection.
• Around the same time, a dial indicator was added to allow for fast, comparative readings and higher resolution.
• The 1980s saw the first digital readout, an advance which eventually led to data collection.
• The early 21st century saw the employment of shop hardened electronics for use in wet environments.
• And just recently, improved scales incorporate a reference point so that they never lose their position.Today you are apt to see digital calipers as the tool of choice for the most common shop, automotive and hobby measuring tasks. But when most people pick up today’s digital caliper, they still see a tool for just measuring outside diameters (OD) and inside diameters (ID). Yet there is a lot of versatility built into this tool. Let’s take a closer look and see what a caliper can do.

Measuring ID Source: Mahr Federal Inc.

Caliper Basics

All calipers, whether vernier, dial or digital, include the same basic components. They have two jaws. The fixed one is the reference jaw and the sliding one makes the measurements. All calipers incorporate a little “hump” where your thumb goes to help move the measuring scale back and forth. Some incorporate a thumbwheel to help improve repeatability by trying to maintain constant gaging pressure (the wheel disengages when the sliding jaw comes into contact with the part).

Usually, the sliding scale will have a round or flat rod associated with it. This extends out the back of the caliper and is used for making depth measurements. Electronic calipers usually also have controls to set the zero point, change units and turn the units on/off. There may even be a connector for sending measured values to a data collection device.

As with any measuring tool, it is important to make sure a caliper is in proper operating condition and ready to do its work. Always check to make sure its calibration is current, the scale moves freely and there are no nicks or burrs on the jaws. Clean the jaws with a soft piece of cloth to remove any dirt. Close the jaws and make sure the instrument reads “0” or set it to zero, using the zero button on a digital caliper or set the dial to zero on a dial caliper.

Fundamental Measurements

When using a vernier, dial or digital caliper, the process of making fundamental OD, ID, depth and step measurements seems pretty obvious. But what may not be so obvious is how easy it can be to make them incorrectly. The caliper is a very operator-dependent tool. If the part is not placed in the middle of the jaws, if the caliper is not 90 degrees to the measurement, or if the operator applies too much force to the sliding scale, there is a good chance the measurement will not be very accurate. Here are some tips:

• When making an outside measurement, place the jaws over the part so that it contacts the fixed jaw in the middle of the anvil.
• Use the small jaws on the top of the caliper for inside measurements. Bring the sliding scale to “0,” then place the part over the jaws. Slide the jaws open until they make contact with the part and are squarely in place.

Measuring Depth Source: Mahr Federal Inc.

• Depth measurements are made with the blade that extends out the back of the caliper. Place the end of the caliper squarely onto the top of the hole to be measured. Ensure the caliper reads zero, then open the caliper until the depth rod meets the bottom of the hole.

Step Measurements Source: Mahr Federal Inc.

• Step measurements are an often overlooked way of making depth measurements. Zero the caliper and place the sliding jaw on the upper step of the part. Then open the jaws of the caliper until the reference jaw contacts the lower step.
• When using a caliper for any measurement, always repeat the process to ensure the measurement is repeatable and reliable.

Measuring Center Distance Source: Mahr Federal Inc.

Compound Measurements

Digital electronics are great. The advent of the electronic calculator has saved countless hours. The electronics in the digital caliper can do the same by doing some of the math during the measurement process.

• Center distance. One check that can be made by making two measurements is finding the center distance between two holes having the same diameter.The first step involves using the inside jaws to measure the diameter of one of the holes. After having the caliper in position and reading the diameter, use the zero button to set the caliper to zero.

  Then, while still using the inside jaws, measure the distance between the two furthest surfaces of the two holes. The caliper reading is the distance between the outside edges of the two holes, minus the diameter of one hole. Since the diameter is twice the radius, the reading is actually the distance between the centers of the two holes.

Comparing ID and OD Source: Mahr Federal Inc.

• Comparing an ID and an OD for fit. Often one may be faced with boring a cylinder to fit a piston or making a shaft to fit a hole. The digital indicator can be used to calculate the fit so one can machine the part to the correct size. Let’s start with a hole and match a shaft for it.First, use the inside jaw set to find the diameter of the hole. While the caliper is in place, reset the zero.

  Now measure the shaft OD using the outside jaws. The caliper will show the difference between the shaft and the hole. A plus dimension will mean the shaft is oversize while a minus dimension will mean the shaft is smaller than the hole. The positive reading can be used to make the shaft to the proper size fit to the hole.

Measuring Thickness Left Source: Mahr Federal Inc.

• How much thickness is left. When creating a blind hole in a part, it may be important to know how much material remains between the bottom of the hole and the other end of the workpiece. A digital caliper can help with this.First use the outside jaw set to measure the total width of the part. Again, while the caliper is in place, use the zero button on the digital caliper to set the tool to zero.

  Then use the depth rod/blade to measure the depth of the hole. The caliper reading is the remaining thickness left in the part. Using this process, the reading will be a negative number-but it represents how much material is left.

US delivery service FedEx reached a deal Tuesday to buy Dutch rival TNT Express for 4.4 billion euros ($4.8 billion), ramping up its EU presence as global e-commerce proliferates.

The companies “reached conditional agreement on a recommended all-cash public offer of 8.00 euros per ordinary TNT Express share,” a joint statement said.

The offer represents a premium of 33 percent over the closing share price of Thursday, and a premium of 42 percent over the average share price over the last three calendar months.

As a part of the agreement, TNT will sell its airline business. The acquisition is estimated to be accomplished in 2016.

TNT Express boss Gunning said the unsolicited offer came at a time of “important transformations” for the company.
“Our people and customers can profit from the true global reach and expanded propositions, while with this offer our shareholders can already reap benefits today that otherwise would only have been available in the longer run,” he said.

A power inverter running off a battery changes DC power to traditional AC power. You can use an inverter to supply power to devices such as televisions, microwaves, computers or power tools. They provide power in areas where you normally would not have access to standard 115-120 Volts AC from the power grid (ex: your home wall outlet). You simply connect the inverter to a 12 volt battery and plug your device into the inverter. This is a great solution for having an easy to use, portable power supply.

Modified Sine Wave InverterThere are many kinds of inverters and many different sources from which they convert power. Some smaller 12 volt inverters convert power from your car battery through the cigarette lighter port on the dashboard. With other kinds of inverters it is important to match them with batteries of the proper type and size. It is important to be discriminating in the purchasing process. If you are using a small inverter with an automotive battery this will work sufficiently. Most car batteries will supply enough power for 30 to 60 minutes before they need to be recharged. You can recharge your battery by either turning on the engine, using a gas generator, or hooking it up to an AC charger. If using your car battery, be sure to run the engine for approximately 10 minutes every hour to keep the battery charged.

The length of runtime that the battery will provide largely depends on the kind of device you are running. If your appliance needs a steady supply of power for a long period of time, that can put a heavy load on the battery. Therefore it is not advised to use your car or truck battery in this situation. The battery can be easily drained to the point where it no longer hold the power necessary to start the engine. This will prevent you from recharging the battery using the vehicle’s alternator. Draining a starter battery like this on a regular basis will harm it and significantly shorten the expected life span.

If you need to run a heavy load through a larger inverter from a car or truck battery, you should only do this while the vehicle is running. Otherwise we recommend you use a deep cycle battery, such as an RV and Marine battery. If you are using a 600 watt inverter or larger, Marine batteries are preferable because they have the capability to withstand being drained deeply and recharged many times. These deep cycle batteries should give you several hundred cycles of charging and discharging. A good rule thumb for batteries is they should not be drained beyond 50% capacity. If you so, it can significantly shorten the life of the battery. If you need more power or longer runtime, you can connect several batteries together in parallel. Creating battery banks is a good alternative to buying a larger battery. Remember, when configuring batteries in parallel, it should done with 12 volt batteries of the same type as one another. Using an inverter to generate power from a battery can be an invaluable resource for anyone who finds themselves away from traditional AC power sources.

12 volt 1000 Watt Pure Sine Wave InverterIf you can, try to use a Pure Sine Wave inverter. The pure sine wave is better for applications, especially those that have sensitive electronic components. The other option, the modified sine wave inverter is less expensive but good for simple applications such as radios. The difference is this: The pure sine wave is natural and the wave is curved. From peak to peak there is a full range of frequency in-between. Modified sine waves are rigid waves, only outputting the top peak and the lower peak alternatively, with no range in-between. Our high end inverters are pure sine wave. We believe that’s the best way to get the AC power you need.

April 5th is Tomb-Sweeping Day of China. It’s also called  Qing Ming Jie in Chinese（All Souls’ Day).  Qing Ming is a time to remember the dead and the dearly departed. More important, it is a period to honour and to pay respect to one’s deceased ancestors and family members. Because it reinforces the ethic of filial piety, Qing Ming is a major Chinese festival. Literally meaning “clear” (Qing) and “bright” (Ming), this Chinese festival falls in early spring, on the 106th day after the winter solstice. It is a “spring” festival, and it is an occasion for the whole family to leave the home and to sweep the graves of their forebears. Chinese being practical people this sweeping of the graves is given an extended period, that is, 10 days before and after Qing Ming day. Among some dialect groups a whole month is allocated.
ORIGIN Qing Ming is popularly associated with Jie Zi Zhui, who lived in Shanxi province in 600 B.C. Legend has it that Jie saved his starving lord’s life by serving a piece of his own leg. When the lord succeeded in becoming the ruler of a small principality, he invited his faithful follower to join him. However, Jie declined his invitation, preferring to lead a hermit’s life with his mother in the mountains. Believing that he could force Jie out by burning the mountain, the lord ordered his men to set the forest on fire. To his consternation, Jie chose to remain where he was and was burnt to death. To commemorate Jie, the lord ordered all fires in every home to be put out on the anniversary of Jie’s death. Thus began the “cold food feast”, a day when no food could be cooked since no fire could be lit. The “cold food” festival occurs on the eve of Qing Ming and is often considered as part of the Qing Ming festival. As time passes, the Qing Ming festival replaced the “cold food” festival. Whatever practice is observed，the basic observation of Qing Ming is to remember one’s elders by making a special effort to visit their graves, ashes or ancestral tablets. To make the visit even more meaningful, some time should be spent to remind the younger members of the family of the lives and contributions of their ancestors, and the story of Jie Zi Zhui who choose death over capitulation.

Canton Fair 2015(The 117th China Import and Export Fair) is the largest biannual China trade fairs held in Guangzhou. We are the most effective way to develop the business relationships you need to succeed in China. It’s no wonder that the Canton Fair 2015 has already become a must see for all those looking for business success in China.

Phase 1: 15th-19th April 2015 9:30-18:00
Phase 2: 23rd-27th April 2015 9:30-18:00
Phase 3: 1st May-5th May 2015 9:30-18:00

China Import and Export Complex

(Canton Fair Complex for short), the largest modernized exhibition center in Asia, is located in Pazhou Island, Guangzhou, China. It is a perfect integratation of human and ecological concerns and high technology and intelligentization, sparkling the world like a shining star.

The complex covers a total construction area of 1,100,000 M² with the indoor exhibition area of 338,000 M² and the outdoor exhibition area of 43,600 M². The Area A has an indoor exhibition area of 130,000 M² and an outdoor exhibition area of 30,000 M², the Area B has an indoor exhibition area of 128,000 M² and an outdoor exhibition area of 13,600 M², and the Area C has an indoor exhibition area of 80,000 M².

Address: No. 380, Yuejiang Zhong Road, Guangzhou, China

We will attend the 117th Canton fair from April.15th to April.19th.

Booth No.: 10.3M23

Warmly welcome your visit.

Contact person: John

Email: [email protected]

Phone: 0086-13819768624

To keep pace with the vigorous development in China as well as the trade relations and amicable exchanges between China and the rest of the world, the Exhibition of Chinese Export Commodities (the precedent of Chinese Export Commodities Fair) was established in the autumn of 1956.

The first Fair was staged in the former Sino-Soviet Friendship Building in the spring of 1957. Looking back at the forty years traversed by the Trade Fair, we can well see that tremendous changes have come off in every aspect of the Fair such as the Fair’s exhibition space, products for export, number of foreign visitors, business turnover, and so on.

The Fair serves as a historical witness to the development of China’s foreign trade, it has faithfully recorded the pace of the country’s growth.

Facilities For Exhibition and Negotiation Improved

Starting with 12, 000 kinds of commodities, the Canton Fair has gradually increased its number of commodities available for export from session to session.Now, there are over 100, 000 kinds or products from famous brands. It features new quality products, specialties and products adapting advanced technology from various parts of the country.

Many enterprises go the Fair armed with their novel products, crack items, etc. in attempts to squeeze their way into the world market via the Guangzhou Trade Fair. In the wake ofrapid developments in China’s economy, especially the home based industries, the Guangzhou Trade Fair was able to obtain more and more supplies and improved its product mix to a great extent. For example, the ratio of manufactured goods has risen from 20% at the outset of the Fair in 1957 to 85.6% in 1995.

To encourage the export of more high-graded products or high value-added products, particularly machinery and electronic products. Special Exhibition Sections have been set up at the Guangzhou Trade Fair. This serves to place special emphasis on these high technology products as well as to make them more prominent.

Quality of Attendance Gradually Improved

In the early days of the Guangzhou Trade Fair, guests came from few countries and regions in Asia. As the Fair developed and as the country becomes more open, an increasing number of foreign business people from various countries and regions have secured business at the Guangzhou Trade Fair. In recent years, each session of the Fair has been visited by more than 80, 000 foreign business people. Till the end of the 83rd Session, the Fair has seen an attendance of more than 2 million businessmen.

Steady Growth in Turnover Volume

The Fair’s business records have shown that, irrespective of which historical period, the Fair remained steady in its trade and the export transactions continue to grow.Even in the ” Three years of Difficulty (1959-1961)”, the Fair’s export trade continued to rise (4.9% over 1959, and 17.5% over 1960). In the “Ten years of national turmoil”, the export business of the Fair, went up inspire of some setbacks. For example, the business concluded at the Autumn Fair’ 70 was worth US $500 million and at the Autumn Fair’ 72, US $ l billion.

The Trading Delegations are organized by their different provinces and municipalities; the exhibition halls itself are arranged by the Chambers of Commerce. While Trading Delegations and exhibition halls are integrated, the exhibitions will be arranged according to trades. Up till the 86th Session, the Fair had done an aggregated export business of US$ 263 billion.

Meba Electric receives many enquires relating to the inspection and testing of electrical installations and the applicable requirements.The enquires vary greatly and cover all aspects of inspection and testing, from the initial verification process of domestic installations to the periodic inspection of major industrial installations.

1. What is an RCD and what does it do?

A residual current device (RCD) is defined as:

‘A mechanical switching device or association of devices intended to cause the opening of the contacts when the residual current attains a given value under specified conditions.’

An RCD is a protective device used to automatically disconnect the electrical supply when an imbalance is detected between live conductors. In the case of a single-phase circuit, the device monitors the difference in currents between the line and neutral conductors.

RCDs are used to provide protection against the specific dangers that may arise in electrical installations, including:
●fault protection;
●additional protection; and
●protection against fire.
An RCD does not provide protection against overcurrent. Overcurrent protection is provided by a fuse or a circuit-breaker. However, combined RCD and circuit-breakers are available and are designated RCBOs.

2. Characteristics of RCDs

RCDs are defined by a series of three main electrical characteristics:
●The rating of the device in amperes, I.
●The rated residual operating current of the protective device in amperes, IΔn.
●Whether the device operates instantaneously or incorporates an intentional time delay to permit discrimination. Such devices are called ‘S’ or Selective.

Devices are manufactured with different values of rated current and rated residual operating current but in this article we will consider the rated residual operating current of the protective device, IΔn.

3. Applications

The correct device must be selected for the particular application. Choosing the wrong device could have serious consequences and could result in electric shock or fire.

4. Labelling

Regulation 514.12.2, states the notice that shall be fixed in a prominent position at or near the origin of the installation, where an installation requires a residual current device:

5. Testing

RCDs must be tested; the requirements are stated in the following Regulations:

●The effectiveness of the RCD must be verified by a test simulating an appropriate fault condition and independent of any test facility, or test button, incorporated in the device.
●Where an RCD with a rated residual operating current, IΔn, not exceeding 30 mA is used to provide additional protection, the operating time must not exceed 40 ms at a residual current of 5 IΔn .
●Tests are made on the load side of the RCD between the line conductor of the protected circuit and the associated cpc. Any load or appliances should be disconnected prior to testing.

6. Test instrument

The test instrument used to test RCDs should be capable of applying the full range of test current to an in-service accuracy, as given in BS EN 61557-6. This in-service reading accuracy will include the effects of voltage variations around the nominal voltage of the tester. To check RCD operation and to minimise danger during the test, the test current should be applied for no longer than 2s. Instruments conforming to BS EN 61557-6 will fulfil the above requirements.

Increased Safety (proof mark for the “e”) is a kind of under normal operating conditions without arcing, sparking electrical equipment to take some additional measures to improve its safety, its internal and external components to prevent possible dangerous temperature arc and spark-proof type of possibility.
In normal operation will not produce sparks, electrical equipment and dangerous temperature arc structure, by taking measures to reduce or control the operating temperature, to ensure the reliability of the electrical connections, increasing the insulation effect and improve housing protection rating to reduce the pollution caused by dirt possibilities and moisture from entering and other measures to reduce the likelihood of failure may cause ignition, increase equipment uptime and provides safety and reliability under fault conditions.
It does not include sparking or arcing equipment (see GB 3836.3 standard) under normal operating conditions.
This type of equipment is mainly used for Zone 2 hazardous locations, and some models can be used for an area, for example, a suitable protective devices increased safety low voltage induction motors, junction boxes.

China’s yuan broke into the top five as a world payment currency in November, overtaking the Canadian dollar and the Australian dollar, the Society for Worldwide Interbank Financial Telecommunication said on Wednesday.

In December, the Chinese currency reached a record high share of 2.17 percent in global payments by value, rising from 0.63 percent in January 2013. It now trails the Japanese yen, which has a share of 2.69 percent.

“The renminbi breaking into the top five world payment currencies is a milestone. It is a great testimony to the internationalization of the renminbi and confirms its transition from an ’emerging’ to a ‘business as usual’ payment currency,” said Wim Raymaekers, head of banking markets at SWIFT.

“The rise of various offshore renminbi clearing centers around the world, including eight new agreements signed with the People’s Bank of China in 2014, was a key driver of this growth,” Raymaekers said.

Global renminbi payments increased in value by 20.3 percent in December, compared with a 14.9 percent rise for all currencies. Over the past two years, the renminbi has shown consistent triple-digit growth with an increase in the value of payments by 321 percent, SWIFT data showed.

China’s currency continued its ascent in global payments settlement, trade and currency investment with the support of a rapidly expanding network of offshore yuan-clearing centers, which facilitate direct access to China’s onshore financial markets, said Fitch Ratings in a report earlier this month.

In 2014, eight offshore yuan-clearing centers were established in major financial centers such as London, Frankfurt and Luxembourg. An additional two were established in Kuala Lumpur and Bangkok. There are now 14 offshore yuan-clearing centers.

Fitch Ratings expects the proliferation of these offshore yuan-clearing centers to drive greater issuance of dim sum bonds (yuan-denominated debt issued offshore) by Chinese and other governments, financial institutions and corporations in 2015.

The circuit breaker maintenance is very important and it must added in  periodical maintenance schedule.Why it so important?It is because of their importance for routine switching and for equipment protection and person.

The need for maintenance of circuit breakers is often not obvious as circuit breakers may remain idle for long periods of time. Breakers that remain idle for 6 months or more should be made to services to ensure it in proper condition and remove any dust or foreign material on mechanism and contacts.

Normally Molded case circuit breakers are designed for no routine maintenance.For long life span,reduce breakdown and safety issued,we must perform for preventive maintenance depending on working condition.

The common problem effected for circuit breaker operation and capability is a dust. Normally dust on the latch surfaces may affect the mechanism and life span for circuit breaker.

1) Cleaning a dust

The major factor for malfunction of molded case circuit breaker is a dust.When it too many stick at terminal connection and mechanism,it will cause a high resistance and tripping device not function properly.

It a serious error and it must not happened because it can cause a damage for equipment and for more danger if involve with human life. Normally every 6 months we must perform dust cleaning for MCCB using vacuum cleaner,dry compress air or smooth brush.Please make precaution about safety issue and isolated thepower supply before perform the cleaning jobs.

2) Tightening the terminal screw

To ensure the molded case circuit breaker have a more life span and avoid to serious damage,every 6 months we must tightening the terminal screw for connection to avoid electric sparking when it loose connection.

Cable will damage and burn if termination for screw is loose.The electric sparking can cause the fire and will effected to molded case circuit breaker reliability and functioning.Use a suitable hand tools and follow manufacture standard torque limit for tightening the screw.

3) Test tripping device

This matter is very important to make sure the tripping mechanism in good condition and functioning because it is a main duty for circuit breaker.Test trip can be done every 3 years.If you not sure how to perform the test,please refer to electrical engineer or electrical contractor.

4)Not removing parts

MCCB in daily maintenance not allowed to remove parts. abnormal immediately stop, do not allow sick operation; Found abnormal operation immediately disconnected, defective machine operation is not allowed.

A contactor is frequently used to remotely turn on and off the main circuit and the AC and DC control current electrical capacity. Has a large capacity and prompt action to control the use of safe and convenient, can frequently operating advantages and remote operation. Mainly used as the master switch of the motor; small generators; electric equipment; master welder and capacitor banks and other equipment switch. Can be turned on and off load current, but can not cut off the short-circuit current, so often associated with thermal fuses and relays, etc. used in conjunction. Mainly by the contact system; electromagnetic mechanism and interrupter devices and other components. Coil and static contact is stationary, when the coil is energized, the electromagnetic force generated by the reaction force to overcome the spring, will be consolidated so that the moving armature suck; static contact contact, thereby turning on the main circuit. When the coil is de-energized, the electromagnetic suction disappeared, the reaction force of the spring armature rely jump, moving contact and static contact also will be isolated, cut off the main circuit.
Divided by current: AC contactors and DC contactors.
Press the main contact points: unipolar; bipolar and tripolar and so on.
Divided by operating mechanism: electromagnetic; pneumatic and hydraulic.

AC contactor has four main components: (1) electromagnetic systems, including attracting coil, moving core and static iron core; (2) contact system, including three sets of main contacts and one or two groups of normally open, normally closed auxiliary contacts, which are linked together and moving core linked to each other; (3) interrupter device, usually larger capacity AC contactor has interrupter device to quickly cut off the arc burn from the main contact ; (4) insulated housings and accessories, all kinds of springs, transmission, short ring, terminal and so on. 1 an arc chute 2 a contact pressure spring piece 3 a main contact 4 a reaction a coil spring 5 6 7 a quiet one short ring a spring core 8 9 a movable core 10 an auxiliary normally open contact 11 an auxiliary NC contacts, exchanges and contacts are widely used for breaking the power and control circuits. It uses the main contact is opened and closed circuit, with auxiliary contacts to execute control commands. Generally only the main contacts normally open contacts, and often two pairs of auxiliary contacts contacts with normally open and normally closed function, small contactors are often used as an intermediate relay with the main circuit. AC contactor contacts made from silver tungsten alloy with good electrical conductivity and high temperature ablative. Electromagnetic contactor works as follows: After the coil is energized, the magnetic flux generated in the core and the electromagnetic attraction. This magnetic attraction to overcome the spring reaction force that the armature pull drive action contact mechanism, normally closed contacts open, normally open contact closure, interlocking or switched lines. Coil power loss or decrease the voltage across the coil, the magnetic attraction is less than the spring reaction force, making the armature release, contact mechanism is reset, disconnect the line or release the interlock.

When the coil is energized, the electromagnetic suction static core, the moving core pull, due to contact with the moving core linkage system, so moving core driven by three runs while moving contacts, contact closure, thereby turning power supply. When the coil is de-energized, suction disappeared, moving core linkage relies in part on the reaction force of the spring and separation, the main contact is open, turn off the power. There are generally three-phase contactors eight points, three inputs, three outputs, there are two control points. Corresponding output and input are easily able to see it. If you want to increase the self-locking, then you also need the output from a terminal point of the line to the control point on it.

First of all should know that AC contactor works. AC contactor works: When the contactor coil is energized, the coil current produces a magnetic field, so that the static magnetic field generated by the electromagnetic attraction attract core movable core, and promote exchanges and contacts will act normally closed contacts open, often open contacts closed, the two are linked. When the coil is de-energized, the electromagnetic attraction disappears, the armature is released under the action of the spring is released, the contacts recover, normally open contacts open, normally closed contact is closed.

A contactor is used to connect or disconnect a DC main circuit or a large capacity with a load control circuit automatic switch, the main control object is a motor, in addition to other electrical loads such as electric heaters, electric welding, lighting equipment, contactors not only turn on and off the circuit, but also has a protective effect of low-voltage release /. Contactor control capacity. Suitable for frequent operation and remote control. Is one of the important components of the automatic control system.
Many of the specifications from the contactor 10A —- specifications have to 250A. Nor non-use it to control the relatively large current, which is required for the device depends on the degree of the automatic control device itself and on the capacity of …
Contactors connected to the internal traction of the magnet can be called up and down movement of the movable contact contacts, also known as contact bridge, called the stationary contact stationary contacts, their role is cut off. And the circuit is turned on,
Auxiliary contacts are. Interlock according to the degree of contact automatic control of the size of the auxiliary contacts. And self-control contactor start. And stop. You can also use it to take some of the signal lights to indicate contactors, and operation of the device, a., it is not complex appliances, if you open yourself to the foundation electrician, a look will understand ,,,, ….
Universal contactor can be broadly divided into the following categories.
An AC contactor. There are electromagnetic bodies. Contact system. Interrupter devices and other components. . Commonly used CJ10. CJ12. CJ12B other series. . .
2 DC contactor, generally used to control the DC electrical equipment, through the coil to the operation principle and structure of DC, DC contactor AC contactor is basically the same.

AC contactor is opened and closed by the main circuit contacts, with auxiliary contacts to execute control commands.
Generally only the main contacts normally open contacts, and often two pairs of auxiliary contacts contacts with normally open and normally closed function, small contactors are often used as an intermediate relay with the main circuit. AC contactor contacts made from silver tungsten alloy with good electrical conductivity and high temperature ablative.
AC contactor operation of the power from the AC solenoids, solenoid by two “mountain” shape the young quartet built silicon, one fixed and put on top of the coil, the operating voltage has a variety to choose from. In order to make the magnetic stability, core pull faces, plus short-circuit loop. AC contactor after the loss of power, relying on spring return.
The other half is the active core, constructed and fixed core to drive the main contacts and auxiliary contacts open short. More than 20 amps interrupter contacts plus a cover, using electromagnetic force generated when disconnecting circuit, quickly pull off the arc, in order to protect the contacts.
AC contactor production as a whole, appearance and performance is improving, but the function remains unchanged. Whether and to what extent the development of technology, the ordinary AC contactor still has its importance.

The annual lantern festival is one of the biggest dates in the Chinese calendar, bringing an end to Chinese New Year celebrations with a variety of colorful lights, decorations and fireworks. Celebrated on the 15th day of the first month of the lunar calendar, in 2015 the festival falls on 5 March.

As early as the Western Han Dynasty(206 BC-AD 25), it had become a festival with great significance. During the Lantern Festival, children go out at night to temples carrying paper lanterns and solve riddles on the lanterns.

Festival Features

In ancient times, the lanterns were fairly simple, and only the emperor and noblemen had large ornate ones. In modern times, lanterns have been embellished with many complex designs. For example, lanterns are now often made in the shape of animals. The lanterns can symbolize the people letting go of their past selves and getting new ones, which they will let go of the next year. The lanterns are almost always red to symbolize good fortune.

In modern times, the festival is sometimes referred to as Chinese Valentine’s Day because of the opportunity it gave young girls and boys to go out in the evening.

Finding love

In the early days, young people were chaperoned in the streets in hopes of finding love. Matchmakers acted busily in hopes of pairing couples. The brightest lanterns were symbolic of good luck and hope. As time has passed, the festival no longer has such implications in most of China, but it is still commercialized as the Chinese equivalent of Valentine’s Day?in China.

Yuanxiao

Main article: Tangyuan (food)
Eaten during the Lantern Festival, tangyuan (Rice ball) is a glutinous rice ball typically filled with sweet red bean paste, sesame paste, or peanut butter.The Chinese people believe the round shape of the balls, and the bowls in which they are served symbolize family togetherness, and that eating tangyuan may bring the family happiness and good luck in the new year.

China has 7 legal festivals in a year, on which all Chinese people will be on vacation. They are New Year’s Day, Spring Festival, Qingming Festival, May Day, Dragon Boat Festival, Mid-Autumn Festival and National Day.

Some people have a half day off on the following four days or anniversaries including Women’s Day, Youth Day, Children’s Day and Army Day of the Chinese People’s Liberation Army. Women have half day off on Women’s Day. Young people over 14 years of age have a half day off on Youth Day. Children under 14 years old have a day off on Children’s Day. Active members of the army have a half-day off on Army Day.

People celebrate many other festivals but they do not have time off: Arbor Day, International Nurses’ Day, Anniversary of the Founding of the Chinese Communist Party, Teachers’ Day and Journalists’ Day.

Here is a detailed 2015 / 2016 / 2017 public holiday schedule for your reference:

The 2015 Spring Festival Travel rush in China will be from Feb.4 to Mar. 15, during which train tickets will be under great demand. We recommend you to book tickets as early as possible, or avoid traveling during the period.

The Spring Festival Travel Rush, also known as Chunyun in Chinese, or Spring Festival Travel Season / Transportation Peak is considered to be the largest annual migration. It is the special period when China faces an extremely high traffic load, which results in great transportation problems, especially on the railway services.

Millions of people working or studying out of their hometowns will be hurrying home to reunite with families as the Chinese Spring Festival approaches. This long-held tradition is the main reason for the rush. The other is that the holiday is one of the two week-long holidays of the year, a perfect travel time for many people. The rush usually begins 15 days ahead of the Chinese Lunar New Year and 25 days after that.

During the 40 days of Chunyun period, the inter-city transportation faces great challenges. The demand for tickets far exceeds the supply. Various measures are adopted to alleviate the problem by opening many temporary trains (numbers starting with letter L), extending the working hours of booking office and opening up more booths. More policemen are deployed to insure the public security. The application of real name system is taken to relieve the difficulty in buying tickets and effectively stop scalpers who profit a lot during this period.

Traveling by Train during Spring Festival Travel Rush
Although the above mentioned measures are taken, traveling by train during the Chinese Spring Festival is still a challenge, especially to foreigners. Here are some tips for you to avoid troubles:

Long Queues in the Booking Office

Crowded Waiting Hall of Xian Railway Station

1. Ticket
If your China tour is happen to be arranged during the Chinese Spring Festival, you had better make early plan and contact a travel agency or ticket agency to book ticket for you (Buy Ticket at TravelChinaGuide.com).

To book the ticket on your own, you have to be in China, know some Chinese, and also have a Chinese bank card that supports online payment if booking through internet. Now a ticket can be bought through internet and telephone 60 days in advance and 58 days prior to departure at stations or some ticket windows in towns and cities (due to adoption of real-name ticket policy and identity verification, some ticket windows are unable to issue tickets for foreign/Hong Kong/Macau/Taiwan passengers). For detailed methods of booking a ticket, read How to Buy Tickets. Please note that if you book through internet, you just need to collect your ticket two hours before departure at stations by showing your valid ID certificate (usually passport for foreign visitors). There are time limits for collecting tickets that booked through telephone. Specifically you need to collect the ticket before 24:00 of the same day if it is booked before 12:00 and before 12:00 of next day if it is booked after 12:00 of that day. During the Spring Festival Rush, there are more chances to get a ticket through internet or telephone than purchasing at stations or ticket windows.

Kind Notice:
To decrease ticket change and refund during 2015 Spring Festival Travel Rush, China Railway Corporation has conducted some measures. During the time period, service fee for refunding a regular ticket will be charged as before (5% of the original ticket fare if refundment is made over 48 hours ahead of departure, 10% if 24 – 48 hours ahead, and 20% if less than 24 hours ahead); when refunding a changed ticket whose departure date is within the rush, the fee will be as high as 20% of the original fare.

2. Taking a Train
During the Spring Festival, the steps of taking a train will take longer time as everywhere of railway stations are crowded with people, so you are advised to get to the station at least 1 hour prior to departure. Most stations will set temporary waiting rooms outside of station halls and air-condition and heat are not available, so remember to wear warm clothes as most cities in China are cold during Spring Festival. Avoid taking heavy luggage as it will be inconvenient for you waiting in lines to enter the station hall, check in, and get onboard. Also, take good care of your young children and luggage when you are in the crowd. After you get into your carriage, keep your luggage in sight or put is under your lower berth, and try not to expose your personal information to strangers. If you happen to take an accommodation or temporary trains that have no heat or air-conditioner, remember to take enough warm clothes with you.

3. Arrival
Do no throw away your ticket after arriving at your destination, as the ticket carries your personal information. When you get out of a station, ignore the “kind-hearted” venders and take official taxies or buses to your hotel.

4. You’d better avoid taking a train during Chinese Spring Festival, and, if condition allows, try other transportation means.

The Chinese New Year, or Spring Festival as it is sometimes called, is a 15-day festival in traditional custom. It can be generally divided into three periods, the days preceding the festival, the festival days and the days after the Spring Festival Day. There are different customs related to each period:

Preceding Days
 Cleaning and Purchasing
Cleaning before the New Year is a tradition in Chinese culture. The grounds, the walls, and every corner of the house need to be cleaned. In Chinese, “Dust” is a homophone for the word “old” (Chen), thus cleaning means to drive the bad luck or the old things away from the house to get ready for a new start.

After cleaning people will go shopping and buy new clothes for the festival. Chinese people believe that since this is a year anew they should buy a lot of new things. Purchasing new items symbolizes welcoming new things and getting ready for a new start.

 Couplets
Chinese couplets are typically pasted on doorways as a part of the festival’s celebration. The custom of pasting couplets can be traced back over one thousand years to the Later Shu State (934 – 965). The original form of modern couplets was called “Taofu”, a piece of peach wood protecting against evil without any writing on. In the Song Dynasty (960 – 1279), the antithetical couplets began to be written on the wood to express people’s good wishes as well as being a decoration. Later, the modern form of couplets appeared replacing peach wood with the red paper. The couplets include antithetical on two sides and a horizontal scroll hanging on the top.

Chinese Paper-Cut – Character ‘Fu’, Meaning Happiness

 Pasting the “Fu”
The Chinese character “Fu”, meaning good fortune or happiness, is used to express people’s good wishes and yearning for the future, so people usually paste it gates or some furniture in the house during the Chinese New Year. Pasting the “Fu” upside down, meaning the arrival of happiness or good fortune, is a widely accepted and popular custom among Chinese people. Other auspicious characters and patterns are added to express good wishes.

In the ancient time, this character and the couplets were written by hand, but now, people can buy printed ones in shopping malls or supermarkets. Some shops even present these printed works to customers who buy something in their shops.

 Paper-Cuts
Auspicious words or pictures are cut on red paper and pasted on windows to express good wishes for the future during the happy event.

New Year Pictures
They originated in Tang Dynasty (618 – 907) with simple patterns to drive away evil. Now they are a kind of decoration for the festival. New meanings and patterns such as conventions, women and babies have been added to the old pictures. Different places in China have different styles of pictures.

 Chinese Cards

Chinese Knot

The Cards are prepared before the festival. In the past, some people sent cards to their friends, parents, teachers and other relatives during the happy event especially when they were not going to be with them on Spring Festival’s Eve. Words of blessing are written on the cards similar to Christmas cards. Now, with the advance of technology, the form of cards has changed, the custom of sending cards continues.
 Send Free New Year Cards to your friends!

 The Gate Gods
In Taoism and folk-custom, the Gods of the Gate, one of the most popular gods, guard houses. Ancient people pasted their pictures on the door to drive away evil and keep their houses safe. Now their pictures are pasted on the doors during the Spring Festival.

 Chinese Knots
Chinese knots are prepared to decorate houses during the festival. They were first used to string jade pendants on clothes as decorations and these knots were widely used in different places such as flute, Xiao (a vertical bamboo flute), curtain and so on as decorations. Now these knots are used as gifts containing the blessing for other people or decorations.

Festival’s Eve & Day
Having reunion dinners, eating dumplings, staying up all night, setting off firecrackers and other activities are the most popular customs of the Spring Festival. Besides, visiting relatives, gifts are also exchanged during the first days of the festival.

Eating Dumplings

Dumplings

The most important food during Chinese New Year is the dumpling (jiaozi). Made with flour and stuffed with different fillings, dumplings are usually eaten on the Eve. Because their shape resembles the Chinese Yuanbao (a kind of money used in ancient times), dumplings are eaten to bring wealth in the coming year. People wrap coins, candy, peanuts, or chestnuts in some of the dumplings to express different blessing for example a coin for wealth, candy for sweet life, peanuts for health and longevity, and chestnuts for vigor. It is also a custom in many parts of China to eat dumplings on Jan. 1st and Jan. 15th of lunar calendar.
 Learn to Make Dumplings

 Staying Up:
The custom of staying up all night dates back to the Northern and Southern Dynasties (420-289). In ancient times, after the reunion dinner, families members chatted around the stove while waiting for the arrival of the new year. Now they watch CCTV New Year’s Gala.

 CCTV New Year’s Gala:
This is a comprehensive art and performance event on the festival’s eve. Since it was first broadcasted in 1983, it has become a beloved performance for most Chinese people. Performances include basic elements such as skits, cross talk (Xiangsheng), acrobatics, songs and dances. Recently more and more foreign artists are appearing which provides Chinese people a window into western cultures. The performance always ends with the song “Cannot Forget Tonight”.

 Firecrackers and Fireworks:
Firecrackers are always set off at midnight. In some places, people also set off firecrackers on the morning of the first day. The use of firecrackers can be traced to 2,000 years ago, when people threw bamboo into the fire to drive away a monster called “Nian”. After gunpowder was invented, firecrackers replaced the bamboo. Because fires can be easily started by the firecrackers, many places ban firecrackers except in designated areas. Fireworks are also set off in the evening of Lantern Festival.

 Lucky Money (Red Envelope):
Lucky money is prepared for children by adults and the elderly and given after the reunion dinner. In folk culture, the children will live safe and sound for the whole year if they get lucky money. This custom still remains and the amount of money is increasing. Children use their money to buy books or other school supplies. Some families also save the money for future use or use it to help cultivate in their children the habit of saving.

Following Days
 Paying New Year’s Visits
A special way for people to express good wishes to each other and an important activity during the festival is to visit their friends and relatives. In ancient times younger people had to salute the elderly by kowtowing; today they salute them by offering good wishes. In response, the older generation gives them money wrapped in red paper.

Generally speaking, people drop in at relatives and friends’ houses, greeting one another with ‘Happy New Year’. This custom has not changed. In some rural places, where families have many relatives, this activity lasts for several days. It is impolite to visit someone without a gift. Therefore, special local products, fruits, desserts, wines and other small gifts should be taken when you visit others. Although, busy people choose to send greetings by telephone or e-mail, the old tradition of paying visits is still popular.

 Temple Fairs
Temple fairs are another tradition of the festival, especially in Beijing. Although they originally were a form of worship connected with temples, now they are more like carnivals and are sometimes held in parks. Traditional cultural performances such as playing diabolo, Chinese traditional magic, puppet shows and so on can be seen. Besides, people can buy all kinds of daily using things at very low prices.

During and after the festival, Beijing has temple fairs almost every day in different places such as Wangfujing, Altar of the Earth and Dragon Pool Park.

The traditional molded case circuit breaker uses thermal magnetic trip units that may be fixed or interchangeable. An MCCB provides protection by combining a temperature sensitive device with a current sensitive electromagnetic device. Both these devices act mechanically on the trip mechanism.

Depending upon the application and required protection, an MCCB will use one or a combination of different trip elements that protect against the following conditions:

■Thermal overload.

In an overload condition, there’s a temperature buildup between the insulation and conductor. If left unchecked, the insulation’s life will drastically reduce, ultimately resulting in a short circuit. This heat is a function of the square of the rms current (F), the resistance in the conductor (R), and the amount of time the current flows (t).

If you monitor current flow and time, you can somewhat predict and detect overload conditions.

■Short-circuit condition.

Usually, a short circuit occurs when abnormally high currents flow as a result of the failure of an insulation system. This high current flow, termed short-circuit current, is limited only by the capabilities of the distribution system. To stop this current flow quickly so that major damage can be prevented, the short circuit or instantaneous element of an MCCB is used.

■Ground fault condition.

A ground fault actually is a type of short circuit, only it’s phase-to-ground, which probably is the most common type of fault on low-voltage systems (600V or less).

Usually, arcing ground-fault currents are not large enough to be detected by the standard MCCB protective device. But, if left undetected, they can increase sufficiently to trip the standard protective device. When this happens, it usually is too late, and the damage is already done. An example of this is a motor having an internal insulation failure. While the current flow may be small, it must be detected and eliminated before major motor damage takes place.