Cable Sizing and Selection Introduction: One of the important aspects of designing any electrical system is to select an appropriate type and size of a cable. Too much small size of cable generates a lot of heat in a cable which will caused permanent damage to an insulation of a cable and using a too much large cable size means we are wasting our money on copper because copper is the costly material for cables. So we must have to select a cable that is neither of too small nor too large size. Further there are many types of cable like stranded cable, ACSR, PVC insulation etc. Cable sizing helps us to select an accurate size (i.e. cross sectional area) and type of cable required for a particular system. Why calculation of cable sizing is …show more content…
Given below is a table having initial and final temperature mention for different types of material, initial temperature is the maximum operating temperature of the cable and the final temperature is the limiting temperature of the cable. Cable Selection By Considering Earth Fault Loop Impedance: The earth fault loop impedance is the most important factor that needs to be taken into account when sizing a cable. It is basically defined as the path followed by fault current when low impedance fault occurs between the phase conductor and earth or it can also be defined as the impedance of the path followed by the current during fault conditions. The higher the impedance the lower will be the fault current and the longer it will take for the circuit protection to operate. For fast protection this fault loop impedance must be low. The reason for the low earth loop impedance is that when short circuit occurs between a live part and the earth, the short circuit current will follow the earth loop and this fault current is large enough that it will trip the circuit breaker and blow the fuses. Earth fault loop impedance directly affects the size of circuit breaker or any other protective devices and size of the
Describe the relationship between temperature and the enzymatic activity of lactase. Of the three temperatures tested, which is the optimal temperature for enzyme activity? Use the results in Data Table 2 to support your answer. Hypothesize how the structure of the lactase relates to the results in Data Table 2. Answer-
Two equations were used in this experiment to determine the initial temperature of the hot water. The first equation
Castle, R. O. and T.L. Youd. "The Houston Fault Problem." Eng. Gelolgists Bull. v. 9, no. 1 (1972): 57-68.
Tectonic plate movement can occur as close as two and up to 450 miles below the Earth’s surface. According to the Indiana Geological Survey, Indiana’s fault lines are further underground than those in California and Alaska, causing more minor quakes in the Midwest. However, Hoosiers should heed the recent earthquake as a warning for future quakes. Earthquakes can and do happen in Indiana, and almost anywhere else in the world. This is the one natural disaster that people cannot avoid no matter their location on Earth. And, being unprepared can have devastating results.
The earth is split into four layers, inner and outer core, the mantle and crust. The top of the mantle and crust make up what is like the skin of our earth (see source 2). The skin is split up like a puzzle and we call these puzzle pieces’ tectonic plates (see source 1). These plates are constantly moving and the plate boundaries (edges of the plates) move and slide past one another. Sometimes as the plates move the plate boundaries become stuck. Pressure builds up in the stuck area over time and eventually breaks. This is why earthquakes occur due to the sudden movement of the plate sliding and breaking creating a fault line to go off. The fault line is the line on which the
There are many factors that affect the damages to a building during and after an earthquake, such as the ground beneath the building (fault line, landfills, bedrock) as well as different the types of building material (wood, steel, brick/masonry) and how it behaves during an earthquake. For example, the wood used for framing in smaller structures (i.e. houses), as well as the steel framing used in larger structures like skyscrapers.
- Temperature was measured after and exact time i.e. 1 minute, 2 minutes, 3 minutes.
Aim: To find out what type of insulation holds the most heat for a can
Circuit breakers and fuses provide equipment and installation protection and operate only in response to an electrical overload or short circuit. Hence these devices cannot detect earth fault currents below their operating current. If they are the only means of protection, it is possible for sufficient earth fault current to flow undetected to constitute an electrical hazard (fire and electrocution).
...distances then Direct Current which range from the power source to the house and then back to the power source for example. The average in an American house is about 60 hertz times in one second. Alternating current travels from the power source where the electricity is generated to your house in a hot line, once it arrives to the house, and then it looks for a resting state and finds in in a neutral line, that's how it makes its way back home.
At this point the desirable crystalline structure of the metal has been reached but it must not be allowed to be heated further as the solution will begin to melt.
...k again. Inspectors do this because over time the electricity passing through a bad wire damages the wire even more in can result in a fire. The fire could cost the owner lots of money in repairs or on appliances and furniture.
... model for the thermodynamics and fluid mechanics calculations for this system need to be presented.
Electricians have to use an earth wire in power station devices because an earth wire creates a safe route for current to flow through. It helps to prevent electric shocks from occurring. If too much current enters the wire the earth wire helps to break the fuse and stop the device from working. The earth wire helps to break the fuse because it has a low resistance. It is crucial that electricians make sure that the earth wire is fitted into the appliances and are wired correctly so that they don’t become loose, as this would cause the workers to get electrocuted. Making sure that the appliances are earthed correctly is important because it means that the device is in very good conditions to use.
Earthquakes belong to the class of most disastrous natural hazards. They result in unexpected and tremendous earth movements. These movements results from dissemination of an enormous amount of intense energy in form of seismic waves which are detected by use of seismograms. The impact of earthquakes leaves behind several landmarks including: destruction of property, extensive disruption of services like sewer and water lines, loss of life, and causes instability in both economic and social components of the affected nation (Webcache 2).