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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 type of oil is used in a 1992 Volvo 240 gl?
Depends on where you live. (The temperature actually...)
Cool:
Low-30(C)- High 20C - 5w/30
Low-22(F) - High 68(F) - 5w/30
Average:
Low-20(C)- High 40(c) - 10w/30
Low-04(F)- High 104(f) - 10w/30
Hot:
Low-15(C)- High 40+(C) 15w/40
Low 15(F) - High 110+(F) 15w/40
What is the main purpose of line PT and bus PT?
"main" purpose depends on who's wants it installed. There are several purposes for bus PTs - metering, relaying, indication to control centers, control (such as for a tap changer on a transformer), sync (typically breaker 1/2 and ring bus configurations). Line PT's can be used for all the above as well.
What is the difference between charge and current?
An electric charge can be either negative or positive. The smallest quantity of negative charge is the amount represented by one electron, and this is exactly equal to the amount of positive charge represented by one proton. In practice, charge is measured in coulombs (C).
Normally, atoms have identical numbers of protons and electrons, so atoms are normally neutral. Atoms that are charged are called 'ions'. A 'positive ion' has an overall positive charge, which means it has more protons than electrons. A 'negative ion' has an overall negative charge, which means it has more electrons than protons.
'Free electons' are negatively-charged sub-atomic particles that have become detached from an atom. Most metals have an abundance of free electrons, and it is a drift of these free electrons that constitute an electric current. In electrolytes (conducting fluids) a current is usually a movement of positive or negative ions.
In both cases, an electric current is a drift of electrical charge. An electric current is measured in amperes (A).
The ampere is an SI base unit, and defined in terms of the force between parallel, current-carrying conductors, due to their magnetic fields. A coulomb is an SI derived unit, defined in terms of current and time, as an ampere second.
What are the metal plates hanging on exterior power lines?
http://www.tactic.be/2013/02/21/what-are-the-metal-plates-hanging-on-exterior-power-lines/
There is not enough information to answer the question. A DC generator is never described in kVA because DC generators are specified in terms of kilowatts.
Does increasing potential difference increase resistance?
Resistance is due to a property specific resistance of material. In no way resistance depends on the voltage applied. This is the case of ordinary conductor. But in case of semi conductor or insulator there may be chances to get a variation of conductance and hence resistance due to potential applied.
Why smps convert ac to dc and again to dc to dc?
first it converts ac to dc as rectifier
But the required dc voltage is obtained by taking average of on & off DC input voltage.
How to calculate a parallel circuit with more than one load in its branches?
If a 'parallel' circuit has more than one load in its (not "it's"!) branches, then it is not a parallel circuit, but a series-parallel circuit! To resolve the circuit, you must first resolve the total resistance of the loads within each branch.
You probably need a 5hp or 7hp motor. Look for HP rating o the 3 phase motor and select the same for single phase. 3 phase has same power but is more efficient at electricity use. Also consider a 3 phase converter. It allows a 3 phase motor to run on single phase service.
How do you convert 50hz to 60hz?
Nowadays converting an electricity service from 50 Hz to 60 Hz can be done by using an expensive electronic invertor unit. Before such units became available you would have to install an even more expensive motor-alternator set which was very large, heavy and noisy.
Some small portable 50 Hz appliances - such as electric shavers, battery chargers for cell-phones, cameras, music and video players, laptop or netbook personal computers, etc. - have been designed to run safely on different supply voltages and frequencies. Whenever that is so, it should be clearly stated on the appliances' rating-plates. In many such cases, where the power needed is low, say less than 30 Watts, a cheap and simple "International Travel Socket Adapter" is all that is needed to make the appliance plug-in and work. Many international airports have shops selling such adapters.
If the power needed is higher (such as for an electric kettle, a fridge, a freezer, a washing machine or a dryer) instead of paying a lot of money for something to convert the available service frequency from 50 Hz to 60 Hz it is much more economic to buy - either new or secondhand - an appliance that has been designed to run on 60 Hz.
For more information see the answers to the Related Questions shown below.
CommentElectric kettles are unaffected by frequency of course, but US-marketed 60-Hz appliances, such as fridges, freezers, washing machines, etc., have been regularly used in places such as the UK (e.g. on US air bases, as well as privately) using a suitably-rated transformer. For example, I used a 230-V 50-Hz washing machine in Canada (60 Hz) for several years, and a large 120-V 60-Hz fridge in the UK for several years, without any damage to either appliance. So, while it would be more economical to buy a new appropriate voltage/frequency appliance in the country in which it is to be used, it also makes economic sense to make use of your existing appliances instead if you decide to ship them.
The joining together of two or more conductors in an electric circuit.
Effect on input voltage on output of a transformer?
transformers are designed as turn ratio specified as 1:1 for 1:to 1 ratio but it could be any empirical number. say 100v on a ratio of 1:0.5 the output voltage will be 50v. I am afraid that is the basic there is more while the output voltage maybe there current maybe not because of internal losses. so the design must include foreseeing losses to get out of a transformer what is required.
Using Ohm's law E = I x R. R = E/I 120/10 = 12 ohms, I = E/R 120/6 = 20 amps. Resistance cut in half, current doubles.
How to compute the ampere if theres no watts given?
V=R*I and W=V*I so W=R*I*I Ex: 10V = 2R *5A 10V *5A= 50W 2R * 5A*5A=50W
Tunnel diodes are usually fabricated from germanium, gallium or gallium arsenide. These all have small forbidden energy gaps and high ion motilities. Silicon is not used in the fabrication of tunnel diodes due to low (Ip,I v)value.
A small tin dot is soldered or alloyed to a heavily doped pellet of n-type Ge, GaSb or GaAs. The pellet is then soldered to anode which is also used for heat dissipation. The cathode contact is connected to the tin dot via a mesh screen used to reduce inductance. The diode has a ceramic body and a hermetically sealing lid on top.
Aequorea GFP is a protein of 238 amino acids with a molecular weight of 27 or 30 kDa.
Source: http://www.cryst.bbk.ac.uk/PPS2/projects/jonda/intro.htm
What is the advantage of having a rotating magnetic field alternator?
1. Rotating field is comparatively light and can run with high speed.
2. High voltage can be generate due to high speed and there is very little difficulty in providing high voltage on a stationary part than a moving part.
3. It is easier to insulate armature coils for high pressure usually generated (6.6 to 11 kV). Since the stator is outside the rotor, so more space is available for greater insulation required for armature winding.
4. Very little difficulty is experience in supplying the field magnet current as it is very low in comparison with the armature current
What motors are in vibrating sex toys?
The sex toys are basically the same vibrator concept used on video game console controllers but differs in application. The vibrator part is a simple DC motors. The output axis of the motor has being connected to an out of axis counterweight. When the circuit is closed by the user the motor turns and so the out of axis counterweight which basically is the component that creates thevibration effect. In that way the user can achieve considerable levels of relaxation while she or he in some cases, enjoy the meaningless natural "waving"!
In some models a variable resistance has being included between the power source and the motor. The resistance controls the amount of voltage passing thru the motor winding. Basically It acts like a "voltage gate". The amount of voltage is directly proportional to the speed of the motor. That means that the lower the resistance the higher the voltage fall on the motor is and the faster the speed goes. This additional 5 cents component, provides the cool speed control feature and also makes the device considerably more expensive.
The speed aspect is directly proportional to the "buzz" and in the more expensive models, the "burrrrrr" effect. The "Burrrrr is also directly proportional to the "mmmmm" factor. Increasing the "buzzing" and definitely the "mmmm" factor will increase. The speed of the motor depends also with the amount of batteries the device uses. Again the higher the voltage the faster the device goes.
To calculate the expected degree of "happiness" factor when using a vibrator with speed control use the following equation which is an application of the basic Ohms Law:
m = V/R
m = "mmmm" or "happiness" factor (current in amps)
V = Voltage which is a constant (and depends with the amount of batteries)
R = Resistance in ohms
On a speed control device this is a variable value
To calculate it:
Divide the maximum resistance between the amount of the resistor steps and repeat the Ohms Law equation using each one of the values of R obtained. There is another way but honesty the topic doesn't deserves the explanation.
WARNING: Please don't do experiments with electric devices at home if you don't have any technical knowledge. DC current is extremely dangerous and could be fatal.
And "mortal" on sensitive areas of the body.
Ohms law is not applicable in higher currents?
No. Ohm's law is applicable in every case. That's why its called a "law". Its just that the calculation becomes more complex as parasitic effects creep in, such as at high frequency, voltage, or current.
ANOTHER ANSWER
Ohm's Law applies in so few circumstances that it hardy qualifies as a law at all! One can validly question whether Ohm's Law should be taught these days!
Ohm's Law is a law of constant proportionality. It ONLY applies to those conductors and other components whose ratio of voltage to current remains constant for variations in voltage. It does not apply to conductors or components whose ratio of voltage to current changes for variations in voltage. So Ohm's Law is not a universal law.
Conductors and other devices which obey Ohm's Law are termed 'linear' or 'ohmic'; those that do not (the majority, in fact!) are termed 'non-linear' or 'non-ohmic'. Some, but not all metals, are linear (e.g. tungsten is not) and most electronic components such as diodes, electrolytes, and gases are non-linear.
The ratio of voltage to current is, of course, resistance. And we can use this ratio to determine what the resistance of a device happens to be for that particular ratio, at any given voltage, even for devices that do not obey Ohm's Law. For non-linear devices, the ratio continuously changes for variations in voltage.
So, it's questionably whether Ohm's Law should be 'law' at all, and one might wonder why we even bother to teach it!
It is quite incorrect to define Ohm's Law as, "resistance equals voltage divided by current", as this equation is derived from the definition of the ohm, and NOT from Ohm's Law -which makes absolutely no reference to resistance.
How many hp is required to drive an alternator?
The more load that is put on the alternator the more power is required to drive it. This is an interesting question and I really do not have the exact number. But I do know from spinning an alternator with my hand that is takes very little power to turn it when it is not connected to anything. But connect it to a battery that is dead and it takes some power to spin it. I would estimate it takes from 2-3 hp depending on the load.
#2 Approximately 1 HP is required to drive an alternator for every 746 watts of electrical power it produces. In practice 1 HP of mechanical power produces a little less than 746 watts at the output because of frictional and resistive losses.
What is difference between financial ac and cost ac?
I believe the intended question was "What is the difference between financial accounting and cost accounting?" The question makes no sense in the categories of electrical and electronics engineering. And so I have added the category of Business to the topic.
The difference between the two types of accounting:
Financial Accounting's goal is for preparing financial statements for use by parties outside of a company's management. The statements that are prepared for stockholders and investors, regulators, analysts and other outside parties present the external view of a company according to established and accepted standards. One of these is known as GAAP, Generally Accepted Accounting Procedures.
Cost Accounting is subcategory of Managerial Accounting which deals with the internal management of the company. Each company's managers may have different needs and so each company may have somewhat different practices for Management Accounting. Cost Accounting deals with the planning and tracking of the costs of operating the company. The needs will vary between kinds of companies. A manufacturer must deal with costs of raw materials and parts, whereas a bank does not need to deal with costs at such a granular level.
