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Creation: 21/03/2012 02:57
Update: 06/06/2012 09:14
Articles 14
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bandu2 : menu_arrow.gif Article: Cable in electrical engineering - 26/04/2012 06:08

A cable laying methods

Cable laying the following: directly buried installation wear pipe laying, shallow groove laying, laying of cable trench and laying of cable tunnels, overhead installation in several ways has advantages and disadvantages, generally considered the urban development planning, the existing buildings density cable line length laying article and its environment impact. Technically, the way of cable tunnels and cable trench laying methods to facilitate the cable construction, maintenance and repair. In some developed countries, cities, urban planning and construction, we have considered the utility tunnels. Practice has proved that utility tunnels running well, and greatly reduces the number of duplication of investment and the phenomenon of repeated excavation of the road, but the huge initial investment, building materials consumption funds in the country, due to a variety of factors, this way of laying is minimal . In contrast, the laying of buried laying and shallow groove is laying an economic model, the buried cable is the most economical and widely Department of electricity laying methods, it is used in suburban and vehicular traffic less frequent. But not conducive to the maintenance and repair of the cable in the event of cable failure, even when using the tester to measure the point of failure, but also to reopen the cable trench, extremely inconvenient. The choice of cable laying, with the actual situation, the vision of development based on project conditions, environmental characteristics, the cable model and the number of factors, determined in accordance with the reasonable requirements and technical and economic principles to meet operational reliability, ease of maintenance.

Second, the selection of cable

Commonly used wire cable manufacturers with oil-immersed cable, PVC insulated cables, XLPE cables, etc., depending on the occasion, but also extends to different types of special cables. With the continuous improvement of production technology and production processes, the cross-linked polyethylene cable has become the most widely used cable products, cable selection should be based on the use of different environments and conditions, combined with the specific circumstances, to choose to minimize the through a variety of tube side rail, road and communication cables such as direct burial and shallow trench laying methods should be considered a plus steel armor cable.

Third, the choice of cable cross-sectional area

Cable cross-sectional area of ​​choice, related to investment in the number of line losses and voltage quality of life of the cable. If you choose the small cross-sectional area, will lead to voltage quality, the line loss is too large, then make the initial investment is too high. Should be based on load forecasting results, development plans, choose a suitable cross-sectional area, so that the power cable to the cable core temperature to meet the maximum operating current requirements and voltage drop requirements, the maximum short-circuit current under the action of thermal stability requirements. Load forecasting difficulty of the work is high, low accuracy, select the cable cross-sectional area, but also meet the city in low voltage distribution network transformation technology guide "and" urban electricity network planning guide "requirements.

Selection of power cables in the three-phase four-wire low-voltage grid, but also consider the zero line cross-sectional area of ​​choice, in public low-voltage network, due to user factors, the three-phase load balancing is difficult to control, improve voltage quality and reduce line losses, the zero-line cross-sectional area should be the same as the phase line cross-sectional area.

Fourth, the cable network and cable network automation

With the constant promotion and use of the wire cable supplies in the distribution network, distribution network can be divided into the cable network and overhead networks (including overhead, cable hybrid network). On the implementation of low voltage distribution network in the "Urban transformation guidelines and supplementary opinions" put forward specific requirements on the cable distribution network automation. Therefore, in the distribution network LAN using a cable network, in accordance with the requirements of distribution automation, new technology, new equipment, qualified to be considered automatic pilot conditions are not ripe, but also in supporting the selection of equipment, consider there is ample room to lay the foundation for the realization of the automation products.

bandu2 : menu_arrow.gif Article: Nest Feathers Thermostat With New Features - 26/04/2012 06:09

Where can you find a thermostat that not only acknowledges your presence by turning itself on, but continues to do its work of controlling heating and cooling even when you are gone? Nest, of course, a home thermostat we introduced you to last year. And to make the versatile Nest even more useful, the company is offering a 2.0 software upgrade for Nest Learning thermostat.

The upgrade includes an expanded energy history view&mdashthis time a full 10 days&mdashavailable as a Web application and via both Android and iPhone smartphones. Nesters will also have access to Airwave, a new and exclusive energy-saving feature which sucks every last breath of Infrared Thermometer cold air from your air conditioning system by shutting off the compressor prematurely but letting the fan continue running.

Most important to non-techies, the Nest will update itself if connected to Wi-Fi. All you have to do is update the Nest mobile app on your smartphone or iPad. Nest, the first learning thermostat on the market, takes cues from your actions beginning on day one, by noting and recording how warm (or cool) you want your home to be at specific times of day. No other &ldquosmart meter&rdquo or programmable thermostat does that.

Spendy, at $250, but well worth it, the Nest also monitors room occupancy. For example, if you have zoned heating, or even if you go away for a day or two without programming desirable room temperatures, clever Nest sets the ambient temperature slightly higher (for air-conditioning) or lower (during heating season) to conserve energy, and does so without a single prompt. And, as Nest&rsquos makers point out, cutting back as little as 100 kilowatt-hours a month will recoup Nest&rsquos cost in two years. Now, if only the relay company can find a way to resolve the patent infringement suit brought by Honeywell in February.

bandu2 : menu_arrow.gif Article: The construction of power cables should be noted that - 26/04/2012 06:09

1, the eddy current problem is caused by high current power cable

Power cables in the construction, steel frame, steel protection tube, laying cable card and overhead, all the steel (iron) and closed-loop formed around the power cables, are likely to form a vortex. In particular, high current power cable systems, eddy current. The construction of the power cable must take measures so that the cable can not be formed around the steel (iron) and closed-loop, to prevent the cable caused by the eddy current phenomenon.

2, the mechanical damage caused by the turn of the power cable

Power cable diameter, the more difficult, transport, laying power cables on the turning radius requirements are more stringent. Power cables in the construction of the turning angle is too large, may make the inside a conductor by mechanical damage, mechanical damage was cable insulation strength decreased, until the failure, the construction found once the first cable fault, when the production of the first cable, three cables head length, and connect to the device due to topographical constraints in phase cable head is rather long and become arched roots damaged the discharge of the cable head. To take measures in the connection of the equipment, appropriate to shorten the length of the in-phase cable head connection, three-phase cable head are not subject to external forces, the Practice has proved that the effect is good. Thus, the cable construction process to minimize the torque cable by cable turn and margin to stay cable, the cable in a natural bent, put an end to the phenomenon of internal mechanical damage.

3, the power cable moisture

Operating experience has shown that, most of the low voltage power cable fault for wire cable manufacturers Joints and terminations, the first failure, the middle connector and terminal head failure due to poor sealing, moisture intrusion caused by the dielectric strength decline, while the medium and low voltage power cables the use of dendritic power supply network, a large number of cable terminal head, so the head of the cable terminal and the middle connector plugging sealed off to ensure safe and reliable operation of cable one of the measures.

4, medium and low voltage power cable ground

In public in the low-voltage power cables online, three-phase load is not equal, therefore, if the use of the metal sheath of the cable, we must consider the grounding of the metal sheath, and to ensure that at any point in the metal casing of non-ground at the normal induced voltage greater than power supply 100V. In my opinion, medium and low voltage cable network cable joints shall be provided with a grounding pole (net), and reliable grounding of the thermostat metal sheath.

bandu2 : menu_arrow.gif Article: LED creative design - 18/05/2012 02:19

Security door handles of the LED light The unlimited potential of the LED, not only the application of the concept of lighting, including the conceptual design of a variety of home, this LED light door handles, from the Italian design company the F.lli Razeto & Casareto by the designers of the company, Giangiacomo Razeto adjustable color LED lights and LED door handle, Massimo Pinto, work together to create, fashion design, built-in 10 colors and three kinds of intensity of light through the built-in wireless PIN code control, issued according to different situations, suitable for hotel, bars and public places such as the environment in case of sudden power failure or fire safety, built-in wireless power system led lighting up, to ensure that people accused of lead safety in an emergency direction. Elegant artificial marble LED lights This is a very simple and refreshing LED lamps, simple shape, like a symbol, the perfect and the inherent design of the lighting designer by Simone Savini sculpture techniques, as well as artificial marble material to the design of this LED lights, looks as a luminous ring, after the lights that light can be surrounded by illuminated the whole room, use little attention to the presence of less than light, the overall shape at one go no assembly joints, like a pure sculptural works of art. For most of the indoor home design is an elegant lighting style decoration. Glowing LED Bicycle Handle And bicycle LED light-emitting accessories, which is a led light bulbs handlebar system in the handle part of the set is equipped with an LED light, in front of not only the road auxiliary lighting for night riding, but also very necessary for traffic safety system to remind and the rear of the motor vehicle is easy to see, but also play the role of the turn signal flashes when the turn. This night the road, through a simple LED handle system will reduce traffic accidents, for friends who like cycling Night, is really very good design! Simple and capable microscope LED lamp Even the hospital lighting design is no longer cold and rigid, this microscope, led lights , as its name implies, the shape of the microscope LED lamp design, simple, clean lines and black and white combination, and can integrate into any modern interior design . Hidden in the concise design designer the Michael Samoriz design intent, designed for designers, artists, or health care workers design and use of inspiration found desk is not only a table, can also be a laboratory, where they can try kinds of imagination, rigorous, revealed some cute, very good lighting design creativity. A board of capsule lamps: Miniflux A wonderful creative designer, Roger Tator, perhaps, from now on, you have to be careful of your drawer, because one day if you just want to eat a cold medicine, there is likely to become a luminous Man: The capsule lamp (Miniflux), looks like a plate capsule, but it can be issued some very nice warm light. No more information to explain its working principle and the power supply, but love surprising analysis is the LED, the battery may be in the packaging, or button batteries. Said the designer, all of these things can be used to the layout window or used to illuminate the drawer - meaning, for example, you opened the drawer in the evening, the capsule can be set to a light-sensitive switch, if it is night, it automatically lights up, then you can influence others to find things ~~       Cpbay - B2B Trade Marketplace for Solar, Fiber Attenuator, Optoelectronics, Power Supply, Security and much more industrial field. Offer trade leads and product information to global buyers and suppliers who focus their business on industrial field.