Electrical Engineering

by placing the insects/animals in the sprayed grain....

No. 12 volts peak to peak would be 6 in the positive polarity and 6 negative polarity. Simply saying 12 volts AC would be 12 volts in each polarity or 24 volts peak to peak

mohm stands for milli ohms, each mohm is a 1/100 of an ohm.

Good question! In US residential wiring, you have 3 wires feeding your home off the transformer: two hots and neutral. The transformer is a 240V center tapped transformer. The neutral is the center tap. Well, that's all fine and good, but your probably asking "what does that mean?" right about now. Well, since the transformer is 240V, you have 240V in between the two hots. The center tap divides the transformer winding in the middle. So between either hot and neutral you get 120V. Neutral is kind of a return wire for 120V circuits. (I say "kind of" because this is AC, current is flowing in both directons.) Well, why is it called neutral, then? At your main service panel a fourth wire comes into play: ground. Ground is simply a heavy safety wire that goes to a 8ft long copper rod driven into the ground. This ground wire is connected to all metal surfaces you touch (panels, screws, metal junction boxes, metal cases on appliances, etc.) In the main panel (and only the main panel) neutral is bonded to ground. So, while neutral is not ground, when everything is correct it should be "neutral," i.e. it has no potential on it. You cannot assume neutral is grounded or safe to touch, however. By the very nature of wire, if there is a current in a wire there is a potential across it. This potential is usually very small, but is still there. The bigger problem is if the neutral connection becomes very resistive or open. Then the neutral will be live as it cannot "return" the energy to the transformer. (Again, not a totally correct analogy, but it gets the point across.) This is why you shouldn't just bond ground to neutral when you don't have a ground wire at a fixture. When a hot wire goes open, fixtures simply fail to operate. When a neutral goes open, the fixture and the neutral between the fixture and the break go live. The fixture will not work, however, giving people a false sence of security. (No the light is not on, yes it can knock you on your butt.) This is why you want to keep your neutrals in good shape. With the neutral you have two hot wires both capable of producing 120V to neutral. Because the hots have 240V across them (and not 0), one hot goes positive while the other hot goes negative. So, let's say you take two loads with a resistance of 60 ohms. You hook the neutrals of the loads up to neutral, one load to one hot, and the other load to the other hot. How much energy flows through the neutral conductor? 0W. This is because the load is "balanced." The amount of energy flowing through load one is equal to the energy flowing through load two. Let's do a testcase for a specific point in time. Let's say hot 1 for load one is at +60V, and hot two for load two is -60V. Ignoring load two, load one has a current of 1A (60V/60ohms=1A) flowing from hot one through the load and back to the transformer through the neutral. We will call current into the transformer on the neutral positive, and current out of the transformer on the neutral negative. So our neutral has a current of 1A on it for load one. Load two has a current of 1A flowing out of the neutral, through load two, and back into the transformer on hot 2. So, by our signing above, load 2 has a current of -1A on the neutral. To calculate the actual current on the neutral, we add the currents for the two bulbs: 1A + -1A = 0A. Current is flowing out hot one, through bulb one, through bulb two, and back to the transformer on hot 2. Make sense? Now, let's say you have the same setup as above, only load 1 is 30ohms. Well, now the neutral has to carry the extra amp of current. The loads are no longer balanced, so the neutral has to carry the difference. At our 60V test case, the current of load one is now 2A. The neutral current is 2A + -1A = 1A. So, this means that the neutral only carries the difference in power between the two hots. This is also why your neutral doesn't need to be twice as heavy as your hots. Let's say you have 200A service. While you can have 400A of current flowing to 120V appliances all over your home, it is actually +200A to half and -200A to the rest. Your neutral carries 0A, not 400A. Let's go back to our last example, with the 60ohm and 30ohm light bulbs. Let's say some unscroupulous DIYer used the conduit the feed is in for a neutral instead of a dedicated neutral wire. Let's say a clamp to the pipe came off and now we have no neutral connection. Now, we had +60 on hot 1 and -60 on hot 2. So our loads have 120V across them. Now, in this ideal test case, our loads appear as a single 90ohm load to the supply. This means that there is 1.334A flowing through our circuit (120V/90ohms = 1.334A). This also means that load 1 us underpowered by 2/3 of an an amp, while load two is overpowered by one third of an amp. If loads one and two were lightbulbs, bulb one would be dim while bulb two would be brilliant. As both loads have 1.334A flowing through them, load one has 40V across it, while load 2 has 80V across it. Remember, at this point they are both supposed to have 60V across them. Our little set up above is how 240/120V applances work. In, say, your dryer, you would have a third load that is directly across the two hots. Load 3 would be your heater, load 1 would be your timer, and load two could be the light in the drum. If your neutral comes open you could toast your timer or bulb. Most appliance manufacturers actually avoid using both hots for 120V, if possible, for this very reason. You can never be sure, though. Now, the other thing to keep in mind is your whole home functions as a 240V/120V appliance. Load 3 is your heavy appliances, the heaters in your dryer, oven, waterheater, etc.. Loads one and two are all your 120V appliances, light fixtures, etc. So while an open neutral doesn't cause too much of a headache on your dryer, it does cause a big headache in your home. Let's say your service neutral comes open, and you have 1500W of appliances on for load 1, and a 100W porch light on for load 2. That porch light is going to burn out very quick. Now it is impossible to garuantee that load 1 will equal load 2 without being obsessive-compulsive. What you can do is when you plan your load and circuits, try to balance them. This will keep current in the neutral low, which will prevent bad connections from burning open. Also, in the event neutral does fail, if the loads are close to balanced you may only see 90V/150V instead of 10V/230V across your 120V loads. Your appliances my be able to tolerate the former until you notice, they can't tolerate the latter. A resistive neutral is a nasty little problem. It has ultimately the same effects as an open neutral, but is much more subtle. With a resisive neutral, there is a connection, but it is bad. When no current is flowing through the neutral, it appears OK. The more current flows through the neutral, the more potential develops across it by ohms law. This means that if your neutral has 25A flowing through it, and has 2 ohms of resistance, the neutral wire has 50V across it. This also means that your neutral bus in your panel is not at 0V (with respect to the transformer), but is at 50V favoring whichever load (1 or 2, as above) is heavier. This means that the lighter load will be overvoltaged. Also note that resistive neutrals get worse with time. Since our example neutral has 25A at 50V on it, it is dissipating 1250W at some point in the wire. This point is the resistive connection, and will get hot as it dissipates all this power. As it gets hot, it will burn a little further open, and the circle continues. NOTE: This procedure involves probing your service panel or heavy outlet while live. This is dangerous. If you are not comfterable with this, call an electrician. They can check for this quickly and tell you exactly what you need to do to fix it. The easiest way is with a AC voltmeter. Leaving everything on as you normally would. Check the voltage from one hot to neutral, then from the other hot to neutral. This can be done at your panel, at a dryer outlet, at an oven outlet, or at any other 240/120V outlet. If the voltages differ by more than a volt or two, you may have a problem. Call an electrician, as work on your main service must be done by someone licenced, and they have lots of experience with this.

Ohmic decay is the wasting away of dipolar magnetic fields. This decaying takes place over a very long period of time.

the ampere i=0is theonlyedge where the e0b and e0c can come together and share the load and that way the two vector diagrams will connected and the load will be less resistive and more on the ek0 and c73 resistive load. the 38f93 relay will be the one to break the load 2u3 and e0b and e0c into diffrent components that will be drawn in the diagram.

Interconnected power system is the one where all the systems ie.. grids for

example are connected to each other...

I wouldn't. I doubt this is possible. Wire, by definition will have inductance. The inductance will increase as the frequency increases, so I guess you could specify a frequency that is extremely low to use the coil at.

The output of an electric fencer is a high voltage pulse of DC voltage.

zero

insulation leakage is known as a ground fault

AC, DC, single phase, 3 phase .... same answer

on a damp day or with water present it may be a bit higher than zero

there is no perfect insulation

if you have more than a milliamp you have problems

Hi,

Always interpoles are connected in series with armature.

N.V.B.V. Prasada Rao

40 watts

You need to identify specifically what is causing the breaker to trip. It could just be that you have to many devices or appliances on the circuit; or it could be a problem with the wiring, switches or outlets. Some steps to take.

1.) Unplug everything from the circuit. If it doesn't trip anymore you had too much plugged in. Identify what can be switched to another circuit.

2.) What device or appliance causes the problem? It is most likely something like a heater or something with a motor; or perhaps too many higher wattage light bulbs.

3.) If the breaker always trips when it rains, you may have a water moisture problem?

4.) If the breaker trips when nothing is connected it may be the breaker or a short in an outlet or switch.

Let's start a list and see if anyone adds additional items: Instrumentation such as laser survey equipment Power distribution and it's integration in roads systems and population centers Sensor technology for monitoring the health of structures Computers for all manner of design and analysis Smart highway systems including motorist aids as well as notices and warnings Lighting systems for roads and population centers

I think you mean a 240 V to 110 V (volts, not watts) transformer! Providing your power tool is rated at 110 V, the answer is yes, because its power rating of 1500 W is well within the capacity of a 3-kV.A transformer.

Drawing block diagram of single phase capasitor start motor?

The purpose of relay for life is to raise money for cancer and find a cure for it.

CHU CHU happens It depends upon the equipment and what you are doing with it. It is easy to remedy the situation but swaping the secondary leads, but the electric drawings must be updated so that people are not confused next time the look at your circuit.

it is a programmable logic device which has a inbuilt memory, clock etc and is required to perform a specific task.

The reason that some capacitors are polarized has to do with their physical construction.

A common type of polarized capacitor is the aluminum electrolytic capacitor. These capacitors use aluminum coated with a thin layer of aluminum oxide for one plate and a conductive solution as the other plate. This strategy yields very high capacitance in a small physical volume because the aluminum oxide dielectric layer can be made extremely thin. Unfortunately, this construction only allows bias in one direction (the aluminum with the aluminum oxide coating must be the anode) because reversing the bias causes the dielectric to break down.

I believe that the chemical reaction that takes place is this: when the aluminum plate coated with aluminum oxide is given a negative charge, the Al+3 ions in the aluminum oxide are reduced back to aluminum metal (taking electrons from the plate). This liberates the oxygen from the aluminum oxide as a gas, which is why reverse-polarizing these capacitors produces out-gassing (and bursting of the physical package of the capacitor if there is no relief valve).

Tantalum electrolytic capacitors have a conceptually similar design. The anode is a tantalum wire with an oxide layer as a dielectric. Subjecting these capacitors to reverse bias also breaks down the dielectric by reducing the tantalum ion back to tantalum metal.

Our local phase rotation is A-B-C. There are many systems that have rotation A-C-B as well. both are correct.

The phase rotation of motor should be always done from motor side i.e The motor terminal box.

You would have infinite amperes if there was no resistance in the battery plates, the battery terminal posts and in the wires that are shorting the battery.

But there is always resistance in those things so - depending on the thickness and therefore the effective resistance of the wires that are shorting the battery - the short circuit current will be from a few amps to many hundreds of amps and, unless someone sees it and acts quickly to remove the cause of the short, that current will continue until the battery either explodes or just runs down very fast.

I've seen them go both ways, along with the shorting wires smoking and then glowing like an electric fire, and also I have seen molten globs of hot metal dripping off from carelessly misplaced tools such as heavy screwdrivers, particularly if made of aluminum, and such things as small wrenches.