Monday, November 28, 2011

Spare tire use and maintenance skills

Spare tire, do not lie when it is always there, only the critical moment was to come forward. Its "low key" Let us take care of it neglected. In fact, the emphasis on the proper use of the spare tire and spare tire on the car to improve the economy and security are very important.

General specifications of Dell Latitude D800 Battery spare tires with the same specifications as the original, but many economic models with a small-size spare tire, the spare tire diameter of less than 1 inch, the width is 135mm. A small spare tire can reduce vehicle weight, lower fuel consumption, cost savings, but also play a role in saving storage space inside the car can be said to serve multiple purposes. Some manufacturers color the spare tire to be painted orange alert, which is to prepare consumers to easily identify the main tires, spare tire to tell consumers to use as little as possible and as soon as possible replacement of the main tires, the vehicle is in motion to ensure the reliability and security.

Spare tire can not control the speed of long-term use and must not exceed 80km / h

Spare tire is not used in place of the main long-term use, because the spare tire of the main frequency of use compared to less friction with the ground is relatively small. Put on the spare tire, due to the friction coefficient of the four tires, tire pressure surface adhesion and different, Dell Inspiron 1501 battery prolonged use of the vehicle's braking system, steering system and suspension system to produce some adverse effects, to bring great traffic safety the risks, while also making the same to the other tires create friction uneven and so on.

After the spare tire put on the speed must be controlled, especially the small-size spare tire, its size, width, load rating and speed rating are not the same and normal tires, so after replacing the spare tire, tire repair to sail as soon as possible main tire repair place and immediately replace it over.

Inspected once a month for four years to replace a spare tire spare tire

Spare tire is idle long, long time, inevitably will be less than atmospheric pressure. Therefore, a spare tire should be checked every month to see if air pressure is large enough. But do not need to replace the spare tire, only to find insufficient air pressure. Acer Aspire 3610 battery Spare tire pressure and tire is not the same now, spare tire in the storage process in order to ensure the shape and use, the choice of the pressure and not the same as used tires, spare tire pressure is generally hit 2.8Bar (280kPa) is required to use check the air pressure should be adjusted again when normal use. Have to pay attention to check the spare tire when the valve core, you can use soapy water and pour over the top to check for leaks, if effervescent, then you have to replace the valve core.

I remember once, weekend outing with friends, go halfway, that child did not air, so get off for a spare tire. Open the trunk remove the spare tire, how such a light? Look closely, we are dumbfounded, a little pressure at all. Fortunately, accompanied by two cars are Jetta, only for another car of the. But the result is more surprising, actually no spare tire with, this man has the audacity to say: "open car ten years, and are run in the urban areas, Dell KM958 Battery spare tire with doing? Only create more weight!" had another car with no gas by the spare tire to continue to move forward, filling the place to find. Came to a tire shop, but not inflated, because the valve core is damaged, but fortunately only a small problem, for a new, red feet of gas, this can continue on the road, but it was so back and forth, hard, a waste of 2 more than an hour. It is recommended that you have to regularly check the spare tire, this time I considered good luck, you think, if you bike long distances, Nikon D90 Battery Grip encountered such a thing, it is in trouble.

In addition to pressure, spare tire had to pay attention to corrosion. The main components of tire rubber, and rubber fear most is the erosion of oil, tire touches the oil, inflation soon eclipse occurs, this will greatly reduce tire life, try not to put oil and prepare child together. If the tire has been stained with oil, to be timely and neutral detergent to wash off the oil.

Spare tire is rubber, stored too long will be the Dell W953G Battery aging phenomenon, we should be careful to check before use for damage or cracks. General aging of the tire period of 4 years, proposed at this time replaced with new spare tire.

Here also tell you a little experience: Nikon D90 Battery Grip after repair should be placed on non-driving wheel on the tire. Some tires were slashed after the repair, the repaired tire to try to replace the non-driving wheel, because driving wheel and non-wheel Redu different, more so the front tire, rear tire is relatively small, otherwise it will very dangerous.

Read these, I think we should create a sense of safety: that spare tire can not be used as normal, just a temporary replacement. And spare tire must be regularly checked to ensure good air pressure, etc., Dell XPS M1210 battery can not let the spare tire non-existent, or when a tire problem, they will let us do nothing, there must be "prepared", and can not suffer.

Wednesday, November 16, 2011

Lightning damage electronic equipment on the substation

Human society into the information age, all kinds of advanced electronic equipment due to extensive and widely used, its chances of being struck by lightning damage greatly increased. In particular substation electronic devices, attached to the subject in a range of lightning protection equipment, the effects of lightning probability greater. And the use of traditional lightning protection measures, the more protection there is improper and should pay attention to.

Lightning hazards in several ways

Ray's Watch and shielding

Thundercloud IBM Thinkpad T41 battery single floating over the earth, dragging its electric charge opposite the charge of surface wind move like a shadow. If the surface via the substation lightning rod or other protrusion, the protrusion to the top of the charge will lead to distortion of the electric field concentration. Lightning started the bottom of the thundercloud before the first pilot of origin by way of intermittent grading leap to the surface development, when 50 ~ 100m from the ground, by the lightning rod and other surface protrusions where the electric field distortion resulting vertical concentration of head-up pilot. Two-phase, into the Watch or shielding of the main discharge stage.

Usually the local surface protrusion height h, below the thundercloud electric field strength greater than and equal to the average 580h-0.7kV / m, then the protrusion will be vulnerable to direct lightning stroke. The reason is the lightning rod of height h can affect the Thundercloud single downward direction of the radius of the originating guide, using the formula expressed as: R = 16.3h0.61m. The formula also shows that the independent rod surface after installation, will be in the vicinity of a large number of scattered hit, and even HP Compaq NC6400 Battery lightning rod for Watch, by the lightning rod for the objects within the scope of protection shielding.

A lightning discharge is generally the main amps to tens of thousands of hundreds of thousands of amps. Instant heat and electric power, will result in concrete pole burst, small cross-section metal melting, causing fire and explosion, the metal conductor connection part of the fracture damage, collapsed buildings, electrical equipment damage.

Lightning counter-attack

Direct lightning stroke current through the resistance of the surface protrusion into the earth diffuser. If the ground resistance of 10Ω, a 30kA lightning current will make the ground potential rise to net 300kV. If the transmission line by lightning from a different substation grounding grid substation, then rising on the ground and power lines will form a great contrast to the potential, leading to transmission lines connected to the electrical equipment damage. Not only transmission lines, HP Pavilion dv1000 Battery power cables, metal pipes any introduction substation will cause lightning counter-attack.

Another lightning counter-attack, damage to the substation's electronic equipment can not be ignored. Lightning current along the substation grounding grid diffuser, on the branch points of the lightning current and potential vary widely. Connected to different potentials to the Internet and other electronic devices. If there have been electrical contact, then beyond its permitted capacity of the ground potential difference will result in equipment damage.

Lightning

Direct lightning stroke discharge of energy through electromagnetic induction and electrostatic induction means to the surrounding radiation, leading to over-discharge device, for the lightning. Clearly, the lightning hazard is a large area, is the bane of electronic equipment.

Data calculations show that, when the HP EliteBook 6930P Battery lightning current is 30kA angle wave, Thundercloud height of 3 km, wire height of 10m, 500m hit from the end of the match midpoint 100m long overhead lines at the ground, the line width on the induced voltage of 150kV value of the oscillation. This wave is electromagnetic induction, and the result of electrostatic induction.

There calculations show that a part of the I-beam structure and the metal Faraday cage connected to 10 layers (60m × 30m × 100m, each high-10m) of the building, was -2.6/40us, 100kA lightning in the roof , the layers of floor 1m vertical height of the induced electric field amounted to several kV / m, with the lower floors tend to be uniform induced electric field strength, but no major strength of the overall attenuation.

In fact, in the production practice, several times the destructive power of lightning in the electrostatic induction electromagnetic induction. Electrostatic induction of the secondary effects of lightning can also be used to explain the theory. Charged thundercloud floating above the surface, surface to bring equal and opposite thundercloud charge. When lightning after lightning charge into the surface point relative hole, surrounded by high-charge region and the ground potential relative to the charge on the COMPAQ Presario CQ70 Battery insulated conductors, like the sudden firing of the waves by the same lightning toward the point of ignition lead equipment, insulation damaged and electronic equipment failure. Of particular note is the high-impedance input of electronic equipment circuits, signal circuits such as lead longer, and directly connected to the metal at a larger size, although for electromagnetic shielding (with shielded cable and the shield grounded at both ends) will continue to suffer bad luck.

Lightning invasion wave

Distant lightning, Watch, or by electrostatic induction and electromagnetic induction method from high-voltage transmission lines, distribution lines, low-voltage power lines, communication lines, cable lines, metal pipes and other means of intrusion substation, due to the relatively long pipeline, and there is a distribution inductance and capacitance, the lightning spread has slowed, the transmission of such a phenomenon with the wave theory to explain the concept known as lightning. Lightning wave transmission line with different parameters of the connection or line endpoint, change in impedance will produce reflection, refraction, wave resistance mutations can result in HP EliteBook 8530P Battery voltage rise at many, and increased equipment damage.

Substation lightning protection measures and the lack of protection for electronic equipment

Lightning rod

Against direct lightning stroke to damage the substation and the general architecture with separate lightning rod lightning rod, some valley line substation lightning protection is used. The structures were divided into air-termination system, deflectors and grounding, lightning protection on the same principle.

In order to prevent the counter, requiring lightning protection device between the air and being a distance not less than 5m, to the distance of not less than 3m. General framework of a lightning rod for 110kV and above, and after the installation of grounding the main focus to network connections.

Independent of the scope of Canon EOS 5D Mark II Battery Grip protection lightning rod on the ground of 1.5h (pin high), high of more than half of the space needle scope of its protection can only be checked within 45 ° angle. Current international law on the popular theory of a ball lightning protection independent checking more realistic. Watch and law theory that the ball around the strike and the thunder cloud with power on, the smaller the energy the more easy to produce lightning shielding. Can be interpreted as the image with a radius with Thundercloud Thundercloud charge proportional to the pilot as the center of the ball, rolled on the ground to hit the lightning rod tip up. Point of contact with the ground ball to the tip of this arc, if you can not touch the protected object was to protect property in the protected area. Such as moderate-intensity Thundercloud (U0 = 50MV), leading the blitz by lightning distance formula rs = 1.63U01.75, can get the ball radius of 133m. Obtained in this case than the radius of the design procedures to protect the larger. Lightning protection by checking specifications, general use of 110kV substation medium-sized 3 5, 35kV Canon Battery Grip substation 1 to 4 of about 30m lightning rod, to cover all the protected areas.

Microwave tower is an independent lightning rod. For the inside of a microwave tower, microwave tower rules of order must be connected to network and communications room. Communications room and the main control room to network integration, network lightning current to discharge through the main control room. By the previous analysis, if the high voltage power distribution room, control room, communications room to protect, monitor, meter, RTU and other places connected to the network far away, and we have the power contacts, the electronic equipment inside the probability of being counter- more.

The annual number of lightning strikes the lightning rod, according to the empirical formula N = 0.015 · n · k (l 5h) (b 5h) 10-6 calculated. Where n is the number of annual thunderstorm days, K is the correction factor to take the metal structure 2. l, b, h, respectively, for the building length, width and height. According to the type in thunderstorm days for the 40-year area, 35kV outdoor substation terminal, bus architecture 5.5m high, the probability of Nikon D60 Battery Grip lightning strikes per year by 0.000454 times, plus a 30m high lightning rod, the 0.027 times each year will be subject to lightning. If a substation with 4 needles on each side separated by 50m, compared to 0.048 times the probability of lightning strikes / year.

Greatly increase the probability of lightning strikes the lightning rod, making the devices currently attached to a large number of update protection, monitoring, and communications integrated microelectronic devices from the experience greatly increased the chances of lightning damage, damage in many ways, so that the power production to bring it Nikon Battery Grip large losses.