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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
let me answer you in layman terms. you can say 1000VA means 1000watt (like in DC circuit).
All electrical devices are made of various components. Two very important components which you would find in almost all the electrical devices are capacitor and inductor.
Now due to these components you will not receive all the power i.e.1000watt.
It might be 980watt. Now the actually power was 1000, which is called apparent power,
but power transmitted was 980, which is called, real power because that is what reached at the end terminal.
But in real terms volt-ampere or VA is unit of apparent power in an AC circuit containing capacitive or inductive reactance(reactance is opposition caused by electronic components to ac current due to capacitance or inductance). Apparent power is the product of source voltage and current i.e. 1VA is the power dessipated when one volt produce one ampere current.
Why three phase induction motor has uniform torque?
The 3-phase currents in the 3 coils of an induction motor will produce a steady rotating magnetic field.
What are the two ways to increase the resistance of a wire?
You don't specify what you are referring to. However, if your question relates to resistance in general, then you should know that resistance is directly-proportional to the length of a conductor and to its resistivity, and inversely-proportional to its cross-sectional area. Resistivity is a characteristic of the material from which a conductor is made, and varies from one material to another.
This means that you can increase resistance by increasing the length of a conductor, or by decreasing its cross-sectional area, or by selecting a conductor manufactured from a material with a greater resistivity (e.g. by using aluminium rather than, say, copper).
What instrument measures very low resistance?
Practically all analog meters are a coil movement of 50micro amps or so to measure a 50amps then becomes a problem the meter will destroy itself. However is a very small shunt of resistance if placed in the path of the 50 ampere flow then a small voltage drop will develop a Mv. THAT A METER CAN SAFELY READ. this voltage drop can be calibrated to show a 50 ampere full meter deflection. Therefore read Mv to get amps. It should be noted that since the small resistance is in series with the circuit there will be an error caused by the shunt resistance. Bottom line it should be small in value as possible to reduce this error for accuracy sake. Digital meter will function the same way as an analog meter meaning shunt mv reading for full scale readout.
How do you convert volts to mva?
Do you mean 'megavolt ampere' (MV.A) or 'millivolt ampere' (mV.A)? By using the incorrect symbol ('mva'), this is not clear.
To determine the apparent power, in volt amperes, you divide the true power, in watts, by the power factor of the load. One volt ampere is one-millionth of a megavolt ampere ('MV.A' -not 'mva') -assuming you don't mean 'millivolt ampere' ('mV.A')!
Are halogen bulbs more energy efficient than traditional incandescent bulbs?
Well, if they're both 40 watt bulbs they use the same amount of electricity. But incandescent bulbs produce a lot of heat as well as light. Fluorescent bulbs don't produce (much) heat, so they can use their power to produce light. So you can use fluorescent bulbs of lower wattage to produce the same amount of light.
So for the same amount of light, fluorescent bulbs use less electricity than incandescent bulbs.
How do you connect a digital voltmeter to a battery?
Use a multimeter that has both scales on it . All you need to do is change the scale from AC to DC
Can a 400 kw generator handle a 460 kw load?
Since the breaker that is installed on the generator set will be sized to the output of the 30 kW generator, the load will stay connected until the thermal trip of the breaker trips the load off line. This will be in the matter of seconds before it happens. To handle a 75 kW load and depending if it is an inductive or a resistive load you will need at least a 80 to 100 kW generator.
In a series circuit How does the voltage from a battery compare to the voltages on each load?
The sum of the currents through the branches of a simple parallel circuit is the current that flows through the voltage source.
Kirchoff's current law: The signed sum of the currents in a series circuit is zero. The sum of the currents in the branches represents one effective path, which is in series with the voltage source, so the two effective currents must be the same.
What color code is used for 4160 volt labels?
Wow your in some serious stuff. Are you worried about rotation. 4160 is not something to be messed with if your not a qualified electrician or lineman. If you mess up you can have a big fire ball on your hands.
What is considered to be the primary side on a step down transformer?
Transformers have windings - typically each winding is designated for a particular voltage. Any one of the windings can be an "output", as any winding can be an "input". Usually for consumers, one of the windings is intended to be 120V for the input. In that case, all of the other windings would be an output.
I should also mention that while you can have several outputs, you can only have one input. Some transformers have the windings color coded to designate input and outputs.
Hope this helps!
How do you get 240 3 phase volts from 480 3 phase volts?
480 volts 3 phase is not a household service in any country and cannot be dealt-with as a DIY project.
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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.
Before you do any work yourself,
on electrical circuits, equipment or appliances,
always use a test meter to ensure the circuit is, in fact, de-energized.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
AnswerYou cannot obtain 240 V from a 480-V three-phase supply, if you are describing a three-phase, four-wire, system. If 240 V is a phase voltage, then the corresponding line voltage must be 415 V. If 480 V is a line voltage, then the corresponding phase voltage must be 277 V.
How does the threshold voltage change during the relative refractory period?
The threshold may increase until a certain point in which the refractory period is so short that it will not allow for stimulus.
Toby G
Attending EMT-P school.
What is the difference between an Inverter and a Converter?
The term converter usually refers to a DC to DC process where a higher or lower voltage is required. Even when a lower DC voltage is needed, it is sometimes more efficient to use a chopper style process rather than a voltage regulator. Converters are often used to condition dirty or highly variable sources like automotive, aircraft, and marine 12VDC systems into a very clean source of power for sensitive electronics. Many converters have very wide input voltage requirements that allow one design for a wide range of power 8-36 volts or more is not unusal. So you can operate even on almost dead batteries, or on a 24-36 V system without modification.
Inverter is a term that implies making AC from DC as in 12VDC input, 120VAC output.
This Is the correct answer:
DC (batteries) 12v to AC (house) 120v Inverter
AC (house) 120v to DC (batteries) 12v Converter
How speed increases when flux decreases in dc shunt motor?
Increasing flux, torque of the dc motor will be increased and speed of the dc motor will be decreased as speed of the dc motor is inversely proportional to that of the flux and the torque of the dc motor is directly proportional to the flux.
What is a Wheatstone bridge used for?
The wheatstone bridge is an instrument used to measure electrical resistance by means of balancing a bridge circuit. The bridge circuit contains two legs, one of which contains the unknown resistance. Variations in wheatstone bridge can be employed to measure inductance, capacitance, and impedance also.
When checking in a load what must be done?
Check that what the consignment note says is included, is included. Or just sign for them with the comment contents not seen, or not examined.
How much water required to generate 1000 kw?
Presumably you are asking about hydroelectric power, as opposed to thermal (steam) power?
The kilowatt is used to measure power. This is the rate at which energy is generated, so it would require a continuous supply of water to generate energy at a rate of 1000 kW.
However, you can determine the rate at which water must flow through a turbine to generate energy at a constant rate of 1000 kW. The relevant equation is:
P = (g i) h
Where P = power (W), g = acceleration due to gravity (9.81 m/s2), i = rate of flow of water (kg/s), and h = head of water (m).
So, if we assume a head of water as, say, 1000 m, then we can determine the rate of flow of water to generate 1000 000 W, as follows:
i = P / (g h) = 1000 000 / (9.81 x 1000) = 102 kg/s
This assumes that the turbo-generator set is 100% efficient which, of course, isn't the case. Assuming the turbo-generator set is, say, 75%, then the flow rate would need to be (102 / 0.75) = 136 kg/s.
Can you use a 1000 watt wiring kit for a 1200 watt amp?
do amps get pushed? Normally a 1200 watt amp would need driving with less than 12 watts of audio.
What is the advantage and disadvantage of open delta bank transformer?
A disadvantage with Open Delta is there are no phase-ground voltage measurements, which is only a disadvantage if directional relaying or distance relaying is needed. Some directional and voltage based ground fault detection relays don't work without the phase to ground input. Since most industrial systems MV are high resistance grounded and ground fault protection is provided by overcurrent, there isn't a need for the phase-ground measurements.
Why will the directional or distance relaying not work in this case?
5. Most directional and distance relays need a voltage to ground reference to compare with the phase current nfr groudn faults. Some can use a zero sequence polarising current from CT's on the neutral of the transformer, but most need phase-neutral voltages for accurate calculation of fault direction and distance.
The relay needs to see a zero sequence voltage to compare to the zero sequence current to find out which direction the current is flowing.
Precise Phase-ground voltages are needed for this type of calculation, whether it is done digitally or with analog circuits or windings, coils and phae shifting circuits.
The voltages provided by the Open Delta do not have enough zero sequence component.
That sounds quite good since the main winding should be insulated from the case. 10Mohm is a very large resistance it is well within normal range of the motor.
What carries the current in a wire?
the metal ;-)
Metal consists - like every material - of protons and neutrons as a nuclei and electrons who orbit them. In a metal the nuclei are so near to each other, that electrons are able to 'jump' from one nucleus to another.
Take the earth as nucleus and the moon as electron. Now imagine, the mars would be so closed to the earth, that the moon is sometimes orbiting the earth and sometimes the mars.
That is ecactly what happens in metal all the time and that's why those electrons are called free electrons. Due to the fact that an electron is containing an electric charge, the the charge does move from one place to another.
So electrons carry the electric charge, while nuclei are not able to bond.
Which part of a circuit is a current?
Current is the flow of electric charge or the rate of the flow of an electric charge through a conductor.
