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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 voltage would you expect across a 1 ohms load?
Since, by Ohm's law, Voltage is amperes times ohms, the voltage one would expect across a 1 ohm load would be 1 volt per ampere.
What is the xo terminal on a transformer used for?
The XO denotes the joined secondary terminal connection of three single coils of a three phase transformer. It is the common return on any unbalanced current of a three phase system.
What is an auxiliary winding necessary?
Por que tienes que preguntarle al maestro de motores 2 el chamo
Why step up and step down process during HV transmission?
In simple terms, in HV transmission the losses are less. So when we want to transmit a large power to a larger distance it is better to go for HV Transmission, however the generation will be in LV level. So in order to transmit the power in HV we need to Step-Up. And then once on the other side of the transmission the loads are all in LV, so to use the transmitted power we have to STEP-DOWN.
I hope this answers your query
AnswerFor a given load, the higher the supply voltage, the lower the resulting load current. We have to transmit electricity at very high voltages in order to prevent enormous voltage drop along the transmission lines, to enable us to use conductors of practical sizes, and to miniminise line losses. Power station generators are limited to voltage outputs of around 30 kV, due to a physical limit to the number of armature windings that they can hold. So we must use transformers to step up these voltages for transmission and, then, to progressively step down the transmission voltages at load centres (cities, etc.).
What is the different phases of statistic?
The different sources of data are published and unpublished documents, govt magazines, personal diaries, memories, letters etc
What is comulative compound wound generator?
A cumulative compound wound generator is a type of electrical generator that combines features of both series and shunt winding configurations. It has a series winding connected to the armature and a shunt winding connected to the field, allowing it to maintain a stable output voltage while providing high starting torque. This design is particularly useful in applications requiring variable loads, as it can adjust its output to meet demand efficiently. The cumulative aspect refers to the way the magnetic fields from both windings work together to enhance the generator's performance.
Can a three phase be converted to single phase using transformers?
Yes if the oven does not have any 3-phase motor, and after conver, the current will be tripple on single phase conductors, so make sure conductor and circuit brakers can handle the current and within limit.
A link can be found below to a related question that has more specifics.
What does a step up and a step down transformer do?
It raises the voltage of the output of the main generator to the level of the grid transmission lines. The actual values depend on the design of the plant and grid system. In the UK the generator output would typically be about 23 kV and the grid line at 400 kV. Very high voltages make transmission of power more economical because the current is correspondingly reduced.
Why dc series motor should start with load?
In DC Series Motors the field is in series with Armature. When the motor starts at
no load, the armature current is very low and so is the field current. As the speed
of DC Motor is inversely proportional to field current, the motor will try to shoot up
to very high speed at no load and it can be dangerous for the motor itself and for
this reason, any DC Motor should always be started on load.
What type of load is a 3 phase compressor motor?
In electrical terms a three phase compressor is a compressor that is driven with a three phase motor. There are compressors that have three pressure heads. The three heads boost the pressure up in higher increments but these are referred to as three stage compressors.
RMS stands for root mean square. RMS is a method for measuring complex AC waveforms. It produces a voltage reading where the constantly varying AC voltage would do the same work as the equivalent DC voltage.
For instance, the standard US outlet voltage is listed as 120V. If you look at the AC waveform on an oscilloscope, you would see the voltage vary from +170 volts to -170 volts for a total of 340 volts peak-to-peak.
Now, if you apply the voltage to, say, a heating element, the voltage would do the same work whether it was positive or negative, so the 170 volts is the value that we would use, not 340.
BUT, being a sinusoidal AC wave, the voltage is not always 170. It varies all the way from near zero to the peak value of 170, so the voltage would not heat the element as hot as a constant (DC) 170 volts would.
If you measure the voltage at many points along the waveform, square each reading, average or calculate the mean of all the squared readings, then take the square root of the average (mean), you end up with a number that represents an equivalent DC voltage that would do the same work. In our example, it would heat the heater as hot. Voila! RMS!
This average is well known for simple sine wave voltages, such as what you would find at your receptacle. The RMS value is 0.707 X the peak voltage. So our 170V example: 170 X 0.707 = 120.19. The opposite is RMS X 1.414 = Peak, or RMS X 2.828 = peak-to-peak. So, 120 X 1.414 = 169.68.
But what if the AC waveform is non-sinusoidal, such as music coming out of an amplifier or impuse noise, or whatever? This is where RMS measurements are really useful, enabling us to find the equivalent power, or noise figure, etc.
For example, the voltage that comes out of a lamp dimmer is all chopped up, definitely non-sinusoidal. If you try to measure this voltage with various standard meters, you will get readings all over the map, because each meter will interpret the screwy waveform differently. If you use a "True RMS" meter, the results will be repeatable and stable, allowing valid comparisons to be made.
By the same token, amplifiers that are rated in "RMS Watts" are fairly well representative as to the actual power you can expect them to produce. Some manufacturers rate their amps in what they call "Peak Power". Remember above how an RMS voltage of 120 is also a peak voltage of 170? This lets the unscrupulous manufacturers put bigger numbers to their amps, making them appear more powerful. Now you know better!
How does electric meter function?
I would like to give you an answer this question but, more information is needed. Is this about your meter readings being sent over the phone/cable connection? In all my years in the business I have never heard of a "remote electricity meter". There are wired and wireless means for monitoring electrical meters. The wireless kind use a coded radio transponder to answer a query from the reader in a passing vehicle, and send a digitized reading. The wired kind operate with communication codes right across the power lines using relatively high frequencies. In 2005 there were over 25 million Italian homes providing remote readings for centralized monitoring of electric consumption. Standards are also being developed for "intelligent" appliances that can be centrally controlled, and for transmission of internet data using power lines. Some of this technology is based on patents from the 1960s and 1970s for communicating digital information across power lines. E.g., Haberly, 1970 (filed 1966), USP 3,509,537.
Calculate the power out put of an amplifier that has an input of 15 μw and a gain of 25dB?
If you want to work in watts, convert 25dB to a scalling factor:
3dB = 2 x input
10dB = 10 x input
20dB = 100 x input
...25dB = 10 ^ (25/10) = 316.2 x input
So the output is 15 micro Watts x 316.2 = (4700)/(10^6) = 4.7 milli watts
If you want to work in dB, then convert 15 micro watts to dB:
10 * log |P| = dB = 10*log |15 x 10^6| = -48.2dB
***When you have very small (ie negative) dB, it is often referred to in dBm, or 1/1000 of dB ( 30 dBm = 0 dB)
so the output is -18.2dBm + 25 = 6.8dBm, or -23.2dB
Why do you try to balance single phase loads on a three phase four wire system?
Because all electrical supply systems are designed to A specific amperage delivery. If you are set up for 1000 amps 3 phase, That means that you are getting 350 amps each on three legs. If you put all your single phase (110volt) stuff on the same leg and have A total of 300 amps of draw then when you try to use several 110 volt items and A three phase piece you will draw too much power on one leg causing an overload. Even though you may only be using A total of 400 amps. Something will give, Most likely the fuse or breaker.
What is meant by the resistance of an electrical component?
Think of it like this:
Friction causes you difficulty in pulling heavy objects on a carpet. This frictional force is similar to electrical resistance. It is one of two ways to define how easily electricity will travel through an electrical element.
How do you get 277 volts from a 480 volt line?
All three phase four wire systems have the ability to produce a voltage to ground or neutral. Take any phase voltage be it primary or secondary and divide it by the sq. root of 3 which equals (1.73) and you will obtain the phase to ground or neutral voltage. The ground and neutral should be of the same potential and when talking about electrical installations these two words get interchanged quite often. Some three phase secondary voltages are 208, 480 and 600 volts. Electricians will talk about voltages of 120/208, 277/480 and 347/600. The first number is the phase to neutral voltage and the second number is the phase to phase voltage.
What are the advantages and disadvantages of the cathode ray tube?
CRT is a mature technology, less expensive, higher contrast, and still produces brighter pictures than a flat-panel display of the same display area. These advantages are slowly being eroded with better flat-panel technology. The cons are more than offsetting its pros. Since CRT uses accelerated electrons and a phosphor screen, it has a little more harmful radiation (if not properly shielded), it uses more energy and generates more heat, and at the end of its life, produces more hazardous materials, not to mention that it occupies a larger footprint and weighs more than a flat-panel display.
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It is 100+j(500-300) ohm = (100+j200) ohm = 223.6<630 ohm
What is the function of the governor of a generator and how exactly is it different from the AVR?
Automatic voltage regulator (AVR) : Depends on the generator output voltage & out put current/Kvar it will change the exciter voltage. Change in excitation voltage controls the reactive power (Kvar).
whereas, a Governor controls the fuel supply to primemover(Engine) in order to control the speed of generator, change in speed (rpm) also controls Active power (KW).
What is the off load voltage of the generator?
Terminal voltage is the voltage between the output terminals of a generator.
What is the main part of ac motor?
shaft, windings, ball bearings, armature, stator, commutator, brushes, terminals, case.
What is thermal runaway in a BJT?
Thermal runaway is where the biasing and operating point is such that the temperature causes the gain to increase, which causes the temperature to increase, which causes the gain to increase, in a vicious circle, leading to destruction of the BJT. Proper biasing and gain management can prevent this from occurring.
What is the resistance in a circuit if two 60ohm's resistors are connected in series?
The equivalent resistance of multiple resistors connected in series is the sum of the
individual resistances.
(10 + 60 + 50) = 120 ohms for this particular trio of resistors in series.
It makes no difference what battery they may be connected to, or if they're connected to
any power supply at all.
What is the cable size for 7.5 kw 3 phase motor?
Assuming it is a 400 V three-phase motor, the phase current is 11 amps, or more if the power factor is less than 1.0 (or the supply voltage is different).
If it is a 400 V motor the cable should be capable of carrying 16 amps, so a 2.5 mm-sq 4-core cable is needed.
