0
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 education and training is required to become a technician?
photoghaphy science english and geography
How the capacitor valve calculate for a for a load?
I assume that you are asking how to calculate the 'value' of a capacitor? Well, it depends what it is used for. If, for example, it is used to improve the power factor of a load, then it is first necessary to determine what the load's existing reactive power is; then, you need to know what reactive power is necessary with the power factor at its desired value; finally you need to difference between the actual and the desired values of reactive power -and this will be the necessary value for the capacitor. Power factor correction capacitors are rated in reactive volt amperes, not farads.
What is maximum output voltage of a transformer?
The secondary voltage (output voltage) of a transformer depends on the turns ratio of the transformer, and is limited by the practical insulation levels of the secondary winding, so can be very high indeed. Power transformers used in electricity transmission systems have secondary voltages in the range of hundreds of kilovolts.
Why use transposition tower in long transmission line?
A 'transposed' tower is one where the vertical sequence of lines on one side of the tower is red-yellow-blue (or A-B-C), while the sequence on the other side is blue-yellow-red (or C-B-A). The effect of this is to introduce some degree of cancellation between the magnetic fields -approximately inversely proportional to the cube of the horizontal distance away from the line, thus reducing the flux density of the magnetic field on either side of the line. In other words, it offers a means of reducing the exposure to the line's electromagnetic field. In the UK, most tower lines are transposed.
You COULD use a huge capacitor, like a bank of 1-farad car stereo caps, to run a motor, because a cap is basically a battery that doesn't hold very much electricity. And if you did it, you'd control the voltage to the motor the same way you would with a battery--resistors, potentiometers, voltage regulators, whatever you like.
I wouldn't do it, though, because a capacitor doesn't hold enough electricity to let the motor run for very long.
Quick note: single phase AC motors all have "run capacitors" and "start capacitors" but those are something else entirely.
CommentI don't think that you will ever find a 1-F (one farad) capacitor! A farad is a HUGE amount of capacitance! Practical capacitors are expressed in picofarads (10-12 farad) or microfarads (10-6 farad), never in farads! Bear in mind that capacitance is directly proportional to the area of its plates -so imagine how huge a 1-F capacitor would have to be!
Running a motor from a capacitor is completely impractical. A capacitor will completely discharge in 5 CR, where Cis the capacitance of the capacitor and R is the resistance connected across its plates.
So, let's pretend from one moment that you can find a 1-F capacitor and let's say the motor has a armature resistance of, say, 50 ohms (quite high!), then the capacitor would completely discharge in 5 x 1 x 50 = 250 s, or a little over 4 minutes!!!! However, if we used a capacitor with a realistic value of capacitance (in microfarads), then the discharge time would be measured in milliseconds! So, not much use for driving a motor!!!
What benefit is there for getting higher open circuit voltage?
There is no particular benefit for having a higher open-circuit (or 'no-load') voltage. In fact, an ideal voltage source would have no internal resistance and, therefore, its open-circuit voltage would be identical to its closed-circuit voltage.
What type of transformer used in bed lamps?
If the bed lamps use a low voltage bulb then the type of transformer will be a step down transformer.
Will earth fault affect batteries discharging in an equipment?
If one terminal of a battery is earthed (and, by this, we normally mean a 'chassis earth'), then an earth fault within the circuit supplied by the opposite terminal will result in the battery being discharged. The rate of discharge depends on the resistance of the earth fault.
What is importat of step down cycloconverter?
Step Down cycloconverters generally Lower the input frequency to a desired value.This has many applications such as activities requiring low frequency namely electric traction systems where simple DC commutating machines are provided with frequencies of order of 16 hz.
Why does voltage change across components but not current?
we know,
v=IR
resistor, capacitor, inductor and other electrical components have their own specific characteristics to drop voltage or to consume voltage at a fixed amount.
the supplied voltage produces a current that changes with the change of the voltage. It doesn't changes simultaneously. so the voltage change across the components. but the current doesn't changes across component...
AnswerThink of a circuit with several loads as being rather like a number of central heating radiators connected in the same way. The same water (current) flows through each radiator. In order for that water to flow, we need a pump to supply pressure (supply voltage) across all the radiators. At the same time, there must also be a pressure difference (voltage drop) across each individual radiator or the water wouldn't flow through it. The sum of these individual pressures must add up to equal the pressure supplied by the pump.
So the same current flows through individual loads, driven by the supply voltage applied across the entire circuit. At the same time, there must also be voltages across individual loads (called 'voltage drops'), or current wouldn't be flowing through them. The sum of the individual voltage drops will equal the supply voltage.
Is the power transformer switched off under light load conditions?
No, the transformer has to supply the load, whether it is light or heavy.
Why does your Fridge thermostat have a resistor across the terminals?
It doesn't. It has an arc suppressor across them.
Would 10mm sq cable suit an 18kw 3 phase 415 volt motor over 25mt length?
The motor would draw about 24 kVA which is 35 amps. For this you would need 10 mm2 cable.
What is the effective voltage for 3 phase 220 VAC power?
If, by 'effective' voltage, you mean 'root-mean-square' (rms) voltage, then 220 V is already expressed in those terms.
Unless otherwise stated, a.c. voltages and currents are always expressed in rms values.
How do transformers de-energize?
'De-energise' simply means to 'disconnect' or to 'switch off. When you switch off the supply to a transformer's primary winding, it de-energises.
How might you reduce the inductance of an antenna coil?
To reduce the inductance of an antenna coil, you can decrease the number of turns in the coil, as inductance is proportional to the square of the number of turns. Additionally, using a smaller core diameter or increasing the spacing between turns can also lower inductance. Employing materials with lower permeability for the core can further contribute to reducing inductance. Finally, adjusting the coil's shape to be more elongated can help achieve the desired inductance reduction.
What types names of windings does the transformer have?
The primary winding is connected to the supply. The secondary winding is connected to the load. A tertiary winding (if used) is a third winding, which may be connected in various ways.
If the transformer is a three-phase transformer, then there are three common configurations: wye (also known as 'star'), delta (also known as 'mesh'), and zig-zag.
Why wire in the coils of electromagnets must be isolated?
Presumably you mean 'insulated', rather than 'isolated'? In which case it is rather obvious, isn't it? If the coils weren't insulated, then the individual windings would short-circuit, and the coil itself would short circuit with the core of the electromagnet.
What is the speed of 190 hp motor?
speed of the motor not depending the H P. It depends upon no: of poles in the stator and the supply frequency.
What voltage would be needed to provide a current of 1A through a 9 ohm resistor and how many volts?
Use Ohm's Law.
Volts = Amps x Ohms
The math is easy in this case and I am sure you can do it.
