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Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
What are the kinds of application of statics of rigid bodies in electrical engineering?
BatSU EE-3102
You have not provided enough information. For 12 volt peak to peak, purely AC signal, there will be no DC (hence purely AC). This means there is no offset - the AC signal peaks at 6 volts and -6 volts. The RMS value of this is VRMS = peak / sqrt(2) = 6 / 1.4.
What is the purpose of a current limiting resistor in a diode circuit?
Diodes are rated to use a certain amount of current. If you go over that amount, it will eventually destroy the device, how long it takes to destroy the device depends on how much more current you are running through it than it is rated at.
Why power factor is not present in direct current?
There is no angular gap between voltage & current in Direct Current. So power factor is always cos 0 deg. i.e. 1 for all tha cases of DC.
Which is a correct statement of Ohm's Law?
The correct statement of Ohm's Law can be written as:
R = V/ I
Where R is resistance
V is the potential difference.
I is the current.
pipe earthing is the best form of earthing and is very cheap in cost.
in this method a galvanised iron pipe of approved length and diameter is placed up right in a permanently wet soil. the size of the pipe depends upon the current to be carried and type of soil usually the pipe used for this purpose is of 38mm and 2.5m in length the depth at which the pipe must be buried depends upon the moisture of the ground. the pipe is placed at a depth of3.75m. the pipe is provided with a tapered casing at the lower end in order to facilitate the driving
How do you change AC motor speed?
A change in frequency of the motor will cause a change in the speed of the AC conveyor motor. This frequency change is brought about by a device called a Variable Frequency Drive. It is used to vary the frequency of the motor from 0 to 100%. I have no idea what the second answer is talking about.
ANSWER: considering that no mention of type of motor is involved the frequency change theory is quite invalid since 50 or 60 Hz AC line runs clocks from banks to wake up calls and while it is true that the frequency is not accurate from second to second it is however very accurate from minutes to minutes.
Current is just a measurement of how many electrons are flowing through a wire in a certain amount of time. The electrons continue to exist, and will continue to flow at their current rate as long as whatever is energizing them continues to have power. So no, current is not used up, but you could describe it as power is being used up, dissipating as heat through the wires and resistors.
Calculate the current where 10 coulombs of charge pass a point in 5 seconds?
Current = charge/time = 10/5 = 2 amperes
Why do you need to solder and tape joint splices?
You don't need to solder a splice, but you may wish to depending on the environment. The key is to have a reliable joint that minimizes joint resistance. Depending on current, type of wire and application there are various splice methods and devices available. On any splice unless it is a ground, you want to just make sure that bare wire isn't exposed to cause a short or safety hazard.
What do you use DC electricity for?
Direct current (dc) electricity is used in many different things, including for example: digital watches and cameras, cellphones, laptop computers, mp3 players, cars, motorbikes ...
What is an ac and DC generator?
An a.c. generator produces alternating current, whereas a d.c. generator produces direct current.
Why is electrical power generally transmitted over long distance at high voltage?
The heating losses in a conductor of resistance R, with current I, are I2 x R. So if you are transmitting power, it is always best to keep the current as low as possible, and this is done by making the voltage high. To keep the size of the wires reasonable, both because of cost and weight, voltage is stepped up to hundreds of kilovolts. I'm not sure what US practice is, but in the UK long distance lines run at 400 KV. This requires large step up transformers at the power station and at the other end, to step voltage down to useable levels.
How much power is in a 120V line?
Most 120 Volt appliances have their Watts listed somewhere on the appliance. Divide this number by 1,000 to get kilowatts. Determine the rate you are charged for electric power. Your electric bill will tell you how many kWh(kilowatt hours) you use, and what the total charge is. Divide your total charge ($?) by the kWh used. In northern Illinois, we are charged about $0.11 per kWh. Multiply the number of hours the appliance is used by its power consumption in kilowatts. This gives you the number of kWh the appliance used. Then multiply that kWh value by the rate for your area that you determined from your electric bill. That will be the cost for the number of hours the appliance was on.
Example: If I toast 2 slices of bread in my toaster, it takes about 3 minutes, or 0.05 hours. My electric bill is $61.38 and I used 558 kwh for that month. Dividing $61.38 by 558, I get about $0.11 per kWh. So, I divide my toaster Wattage (750) by 1,000 to get 0.75 kW. So now I can multiply the hours that the appliance was used (0.05) by its power consumption rate in kW (0.75). This result is 0.0375 kWh of energy used. Then I can multiply the rate the electric company charges ($0.11) by the energy used (0.0375 kWh). The final result is $0.004125.
How do you guide to residential electrical installation?
Please re-phrase the question for clarity. A good how to book can be found at your local book store. What one will be best can be determined best by you. Some people love technical type manuals others like a comentary type story or Q and A. If you know your reading style, it will be much easier to determine which book to use. Although i did not completely understand the question i hope this helps you. Good Luck Terry North
For a three-phase, three-wire, system there are three conductors called 'line conductors', and there is a voltage between any pair of line conductors, so there are three voltages.
For a three-phase, four-wire, system there are four conductors: three 'line conductors' and a 'neutral' conductor. So there are three line voltages (voltages between lines) and three phase voltages (voltages between any line conductor and a neutral conductor).
What are the advantages of open end winding induction motor over conventional induction motor?
Open ended induction motor - i assume you are talking about split phase induction motor. With these motors old style speed controlling method using external resistors can be used. However this is now obsolete.
Why do you want to change your current role?
Because i want to find a job more stimulating, i was'nt getting job satisfaction and would like to further my career.
How can we calculate cable size for 800A breaker?
Wire sizing is based on the load that the conductors carry. The breaker is then sized to protect the wire. To get to an amperage the wires are going to have to be paralleled. The calculations are already sized in the electrical code books, CEC and NEC. These are code books used by North America electricians.
A 500 MCM conductor with an insulation factor of 90 degrees C is rated at 430 amps.
Four 500 MCM conductors paralleled will give you an ampacity of 1720 amps. The breaker will need to have a 500 MCM 4 barrel lug to receive the conductors. The same thing with the load end, it will also need a four barrel 500 MCM lug.
What are splices and taps in wires?
A tap splice is a splice that is made usually in a mid span of aerial feeder conductors. It is used to connect a home from a utility company's secondary service drop on the street where the span is between poles and it is not convenient to connect a mid span home to either pole. Tap splices are also made in underground services where the utility feeders are in conduit between junction boxes. Each home along the route has an underground conduit from the junction box to the homes meter base. In the junction box where the home service wires connect to the utility feeders, this splice is known as a tap splice.
What is cooling system in transformer?
oil is used in high voltage transformers. It must be serviced and changed by usually major electric service providers Transformer oil has heat conductive properties, along with its insulating properties, that take the heat build up from the windings to the outer case of the transformer. The transformer tank is used as a heat sink to allow the outside ambient temperature to cool it down. On big KVA transformers there are heat tubes on the outside of the tank. On even bigger transformers there are fins that the oil travels through. This provides a bigger surface area to dissipate the heat. The tubes and fins also allow thermal siphon of the oil through the tubes by drawing in the cooler oil at the bottom of the tank and moving it to the top of the tank where the hotter oil is. This circulation greatly increases the cooling ability of the oil to keep the transformer with in its allowable temperature rate of rise zone.
What is working principle of electronic energy meter?
The working principle of an electronic energy meter is a device that measures the electronic energy consumed (usually in KWh). It is often incased in glass and has a disk that rotates that measures the amount of power (product of current and voltage) the flows through the meter. The rotation is then integrated over time either by mechanical dials or an electronic digital counter to determine the total energy used.
To simplify reading, many modern ones also contain a type of radio transponder that can be interrogated remotely from the meter reader's vehicle so he/she no longer has to find, read, and write down the value on every meter on his route.
What is single phase and 3 phase power system?
single phase motor have a single winding and in three phase motor have a three winding
AnswerA three-phase alternator (generator) has three stator windings, physically displaced from each other by 120 degrees. When the field winding rotates, it induces three, separate, voltages into each winding which are then displaced from each other by 120 electrical degrees.Depending on the way in which the alternator's windings are connected, you then have either three or four external wires that will connect that alternator to the load (usually via three-phase transformers). Three of these wires are 'hot' and called 'line conductors' and the fourth is called a 'neutral conductor'.
The potential of each line conductor is displaced from the other line conductors by 120 degrees, and the potential difference between each line conductor is called a 'line voltage'. The potential difference between any line conductor and the neutral is called a 'phase voltage'. For a four-wire system, the line voltage is 1.732 time the value of the line voltage.
A single phase connection is obtained by connecting a single-phase load either between any two line conductors of the three-phase system, or between one of the line conductors and the neutral conductor -depending on the level of voltage required.
Alternatively, a single-phase system could comprise an alternator with just one winding, and supplying two conductors, a line conductor and a neutral conductor.
Answer: Single-phase is a pair of conductors providing ac power, with the voltage following a sine-wave of variation with time, usually with a frequency of 50 or 60 cycles per second (Hz). Three-phase uses three single-phase supplies with the sine-waves peaking 120 degrees apart during one 360-degree cycle.
That is useful because it means that the instantaneous sum of the three currents is zero, and therefore the three neutral wires can be replaced by one wire that is common to all three circuits and no net current flows in the neutral provided the three circuits supply equal currents. When that happens no power is lost in the neutral, and the transmission losses have been halved when compared with three separate single-phase supplies.
In many cases the neutral wire is retained in case the three circuits have to supply unequal currents, which is a three-phase four-wire system. Alternatively when the load is balanced (equal currents in the three circuits) the neutral can be omitted altogether and that is a three-phase three-wire system.
Power distribution worldwide uses three-phase for efficient transmission, except for low-power low-voltage supplies (120/240v) as used for residential properties and small businesses.
