How to find current carrying capacity of 1 or 3 core pvc electric cables? what is the formula for calculation?
410537
The ampacity (current-carrying capacity) of any given cable is determined by the maximum heat that its insulation and jacket can withstand. The heat dissipating ability of the conductor is reduced by the electrical insulation around the conductor. If the current in the conductor is too high, the insulation would be damaged long before the conductor melts. Common standard ratings of cable insulation are 60, 90, or 105 degrees Celsius depending on the type of insulation.\n\nThe ampacity for a cable is based on current, ambient temperature, and environmental conditions adjacent to the cable. In a long run of cable different conditions govern, and installation regulations specify that the most severe condition along the run governs the cable's rating. Cables run in wet or oily locations may carry a lower temperature rating than in a dry installation. Special calculations are necessary for multiple circuits in proximity in adjacent raceways. When multiple cables are bundled together, each contributes heat to the bundle and diminishes the amount of cooling air that can flow past the individual cables. The overall ampacity of the insulated conductors in a bundle of more than 3 must be derated, whether in a raceway or cable. Usually the de-rating factor is tabulated in the wiring regulations.\n\nFor a table on AWG american wire gage and ampacity check out the following link:
871196
Don't you just need to balance forces in orthogonal directions and then use these components to get the forces along the cable?\n\nSince the sign is stationary, vector sum of forces must be zero.  Sketch a free body diagram and label known forces.
567404
I am sure there is, that's why we had to learn the geometry and algebra.  I am sorry I don't know what it is.  I would bet it has to do with the weight of the load depends on the type of cable you would use and amount of cable depends on the volume of the load...see?
309325
Since m*C*dT=Q;\n\nHeat capacity=135000 J/(5100 g*(31.5K - 18K))= 1.96 J/gK\n\n(K for Kelvin)
797208
Not the easiest thing to explain via email but the best way to start is to understand clearly the function of the symbols shown in diagram. Once you understand what each item does find a starting point - usually the power supply and walk through it. ANother way is to get the corresponding termination diagram. I find them much easier to understand.
139303
the physics formula that can be applied here is:\n\nvt = x, where v = speed tub is being filled, t = minutes, x = number of tubs filled.\n\nsince there are three valves, each contributes to the filling/emptying of the tub.  thus, v = valve1 + valve2+ valve3.\n\nt is unknown, the minutes we are solving for.\n\nx = 1, since we want the time that it takes to fill 1 tub, no more.  putting these all into the equation:\n\n[valve1 + valve2 + valve3]t = 1 tub\n\n[(1/3)tub/min. + (1/5)tub/min. - (2/15)tub/min.]t = 1 tub\n\n[(2/5)tub/min.]t = 1 tub\n\nt = (5/2)min. = 2.5 minutes\n\nchecking the answer, in 2.5 minutes, valve 1 will fill the tub 5/6 of the way, valve 2 will fill it 1/2 of the way, and valve 3 will empty it 1/3 of the way.  (5/6) + (1/2) - (1/3) = 1, therefore our answer works!\n\nt = 2.5min.
568661
Let's see if I can remember...\n\na) Find the current flowing through a DC circuit, from a 12V battery and a 3 ohm resistor.\n\nBy Ohm's Law, V = IR, where\n\nResistance = ohms = R\nCurrent = amperes = I\nVoltage = volts = V\n \nYou want to find the current, in amperes, so we switch the equation around a little: if V = IR, that also means that I = V/R (dividing both sides by the same thing gives the same answer).\n\nNow, plug in our values:\nI = (12 volts/ 3 ohms) = 4 amperes\n\nb) what is the current in an AC circuit, with 120 V and 60 W lightbulb.\nIn this case, Watts is a unit of power, and volts is a unit of resistance, and amperes is a unit of current. Electrical power is amperes times volts, or W = I * V\n\nIn this case, W = 60 and V = 120, so we rearrange it:\nW = I * V or \nI = W/V or \nI = (60 watts/120 volts) = 0.5 A\n\nAs for the atom model problem...hmmm! Si is the symbol for silicon. It has an atomic number of 14 (not 16) and an atomic mass of 28.085. According to the Bohr model of an atom, every atom has electrons (with no mass, and a negative charge), protons (with a mass, and a positive charge) and neutrons (with a mass, and no charge). The number of protons and electrons must be equal in order for the atom to have no charge, if one is greater than the other, it results in an ion (positive ion if protons are greater than electrons, negative ion if electrons are greater than protons). Electrons orbit around a nucleus of protons and neutrons.\n\nNow, an element's atomic number (14 in this case) is the same as the number of protons (and electrons, since the element is not an ion, in this case). So a silicon atom has 14 electrons orbiting around its nucleus, and its nucleus also has 14 protons and a number of neutrons.\n\nThe electrons orbit in shells around the nucleus. In the case of silicon, the inner shell has two electrons, the next shell has the maximum number possible or eight, and the third shell has the other electrons, or four. (To check, 2+8+4 = 14.) \n\nFinally, the number of neutrons in the nucleus can be calculated if we know how much a neutron weighs and how much a proton weighs. If N is the weight of a neutron, and P is the weight of a proton, and the number of neutrons is n1, and the number of protons is n2, and we say that the atomic weight is A, we have:\n\nA = (n1 * N) + (n2 * P)\n\nWe want to find n1, so we rearrange this like:\n(n1 * N) + (n2 * P) = A\n(n1 * N) = A - (n2 * P)\nn1 = (A - (n2 * P))/N\n\nNow all we have to do is plug in the relevant values, and we shall get the number of neutrons in an atom of silicon:\nA = 28.085\nn2 = 14\nP = \nN = \n\nSo, n1 = (A - (n2 * P))/N = \n\nSimple! Or at least, simpler! :)\n\nI know what you're going through...getting back into the swing of things after you've been away from school for a long time can be a pain. But keep on plugging away, it's worth it in the end! Good luck!
472581
The equation for this is relatively simple.\n\nVp/Vs = Np/Ns\n\nWhere: \nVp=Voltage primary winding.\nVs=Voltage secondary winding.\nNp=Number of coil turns on the primary winding.\nNs=Number of coil turns on the secondary winding.\n\nThus taking that into consideration you should be able to get the voltage for both sides.  To get the current on both sides.  Just realize that you need the resistance.\nOr if you have the current on one side, use the conservation of Power equation:\n\nVpIp=VsIs\n\nWhere: \nVp=Voltage primary winding.\nVs=Voltage secondary winding.\nIp=Current in the primary winding.\nIs=Current in the secondary winding.
740779
use pv=nrt and you can get the answers
756382
The resolution vector of the two attached cables has to equal the opposite of the traffic light's downward vector of 980N.  Draw the two vectors head to tail.  They will make a 70 degree angle. Depending on which vector you move, the angle at the top where the resultant starts will be 50 or 40, and at the bottom will be 60 or 30 degrees.  Use the Law of Sines to find the magnitude (tension) of each vector (cable).  \n\nsin 70 / 980 = sin 50 / x where x is the cable at 30 degrees; x = 798.9N\n\nsin 70/980 = sin 60 / y where y is 40 degree cable:\nx = 903.2 N\n\nIs that what you got?
1125882
The best thing to do is to use a table of wire gauge versus current and resistance.  The tables usually provide resistance per linear foot  so that for a given length of wire of a particular gauge, you can determine its resistance.  This is important because the wire's resistance combined with the current that your load draws will cause a voltage drop across the wire so that you do not have the same voltage at the load as you provided from your power source. This follows Ohm's law (  V = IR).  You should size the wire conservatively and follow local codes if this is for commercial or residential purposes.
437730
See http://members.aol.com/logan20/elecspon.html for the equation to use.
331292
See the other postings of this question.  The equation is\n\nhttp://members.aol.com/logan20/elecspon.html
958888
Use the formula:\nQ (heat) = Cp (Heat Capacity) * delta T (Change in Temperature)
733256
Single phase circuits have two terminals one "hot" and the other ground.  v(t)=120*cos(2*pi*60*t)\n\nThree phase have three hot terminals (each 120 degrees out of phase with one another) and one ground:\nv1(t)=120*cos(2*pi*60*t+0 deg)\nv2(t)=120*cos(2*pi*60*t+120 deg)\nv3(t)=120*cos(2*pi*60*t+240 deg)
252526
none. amps has no weight, its a flow of current. It's like calculating tonnage to speed. How many tons does 100 mph represent?
909402
Well, it's Wednesday morning.  I hope this answer still has some value to you.\n\nI started by summing the torques at the hinge.  There are three:\nT(light)=5*9.8*7.5*cos(37)\nT(cable)=-tension*6.31*sin(37)\nT(pole)=8*97.5/2)*cos(37)\n\nThese all sum to zero.\n\nI computed tension=140.5\n\nThe sum of the horizontal forces must be zero.\nThese are the tension in the cable and the horizontal reaction force at the hing.  So the horizontal component is 140.5\nThe vertical forces are the weights of the pole and the light offset by the vertical reaction force at the hinge\nthe vertical component is (8+5)*9.8\n=127.4\n\nI checked the answer by computing the magnitude of the reaction force two ways.  Using Pythagorean theorem \nsqrt(140.5^2+127.4^2)\n=189\n\nI then summed the forces parallel to the pole:\n5*9.8*sin(37)\n8*9.8*sin(37)\n140.5*cos(37)\n=189\n\nj