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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 is the function of the triggering circuit in an oscilloscope?

It's for analyzing aperiodic waveforms.

An aperiodic waveform is one that occurs at...well, random intervals. The sine wave of a powerline is a periodic waveform: it runs all the time, so the period of the wave is either 0.0166 seconds (60 Hz power), 0.02 seconds (50 Hz power) or 0.0025 seconds (400 Hz aircraft power).

If the wave just comes up whenever it feels like it, that's an aperiodic waveform, and it's much easier to analyze them if the sweep only starts at the beginning of a wave.

How do you calculate kwh in three phase?

In exactly the same way as you do so for a single-phase load. It's the product of the power of the load, expressed in kilowatts, and the during of operation, expressed in hours. (And the symbol of kilowatt hours is 'kW.h', not 'kwh')

What measuring instrument is used to measure potential difference?

To Measure Voltage or potential difference you can use volt meter, there are diferent methode to measure DC voltage and AC Voltage.use a AVO meter and you can choose Voltage in each voltage range on the selector.a Volt meter instrument you can find it by manual methode and digital .Dont forget to read manual book before you will measure the voltage.

Comment

'Potential difference' is exactly the same thing as 'voltage'; they are synonymous.

What are the factors effect on the value of impedance when connect inductor and resistor in series?

Impedance (expressed in ohms) is the vector sum of a load's resistance and inductive reactance.

Resistance is determined by the length, cross-sectional area, and resistivity of the conductor, while the inductive reactance is affected by the inductance of the load and the frequency of the supply.

Resistance can also be affected by the 'skin effect' which causes the current to flow towards the surface of a conductor, reducing the effective cross-sectional area of the conductor. This is called 'a.c. resistance', and increases with frequency (at normal mains frequency, a.c. resistance is not markedly greater than d.c. resistance).

Why instruments are connected on low voltage side of the transformer while performing no load test?

since we need to get desired or rated voltage, so if it is connected in high voltage side of the transformer, voltage supply will be more, and hence the current will be more than the required amount. this is the reason why the instruments re connected at the low voltage of the transformer while performing no load test.

What is the rating of circuit breaker needed for a 500kva load?

To answer this question a voltage needs to be stated and whether the load is three phase or single phase. Without the voltage the amperage can not be calculated. For single phase, Amps = kva x 1000/voltage, for three phase, Amps = kva x 1000/1.73 x voltage.

What is zero current transformer?

It is a transformer with No load attach to it.

Is it possible to use a moving coil loudspeaker instead of a moving coil microphone?

Yes, but the sensitivity and frequency response will be very poor. The diaphragm on a microphone, corresponding to the voice coil and cone on a speaker, is extraordinarily light and compliant.

Is the term potential used instead of voltage to indicate electrical pressure?

The terms potential and voltage are somewhat interchangeable when used to indicate electric pressure. The proper term is voltage, or volts, which is actually a combined term that means joules per coulomb or, in simpler terms, energy per charge.

What would happen to an electric motor if the amount of current in the motor was reduced?

Depends on what sort of motor it was. If it was the sort you find in an ordinary electric drill, then it would slow down. But rememer, the only way you can reasonably reduce the current in to motor is to reduce the voltage in the supply. A motor takes what current it can, dependent on Ohm's Law. To reduce the current, reduce the voltage.

But in a three-phase motor, the speed being dependent on the rotation of the phases, it would more or less stay the same. But this assumes it's not under load. A load would cause it to slow down.

What is the efficiency of a 240 volt single phase 3 horse power motor which draws 12 amps under full load?

This might be a homework question, in which case you find the power, which is 3 x 746 watts, and divide by the voltage to find the current taken if the efficiency is 100%, and that is 9.325 amps. So the efficiency is 9.325/12 or 77.7%.

In practice the question is complicated by the power factor of the motor, which means that the watts taken are less than the volts times amps. The power factor could well be 0.777, in which case the efficiency would be 100%.

Will you get a electric shock when the negative terminal of the dc power supply is grounded and the positive terminal is held by us?

Only if we are also in contact, directly or indirectly, with ground.

By ohm's law, current is voltage divided by resistance. Conductance is the inverse of resistance, so current is voltage times conductance. No conductance - no current.

Will a DC to AC inverter power a 13.5 Amp motor?

It depends on the inverter. Keep in mind that the average starting current of a motor is four times its running current, so the inverter would need to be able to handle a 54 Amp transient. (Or higher, depending on design margins.)

What is the bacteremic phase?

There are two stages in the disease process. The first stage is during the active Leptospira infection and is called the bacteremic or septicemic phase. The bacteremic phase lasts from three to seven days and presents as typical flu-like symptoms.

When the dc motor is connected across an AC supply then?

It depends on the construction of the motor. If the field winding is connected in series with the armaturewinding, the motor is like a universal motor and will probably operate normally. If the field winding is connected in parallel with the armature, the motor will not run, but will draw current, make noise and get hot.

Why does your electric trip when you plug in a power saw?

because when you plug in a power saw,it has to struggle from the inside the saw

your electrics trip out when there is to much power in use, otherwise if your using an adapter or extension they may be faulty or it could be a faulty saw, i would start by checking any leads have not been gouged or have cuts in them including the wire leading to your saw.

How much does air expand at 35000 degrees?

If you assume pressure stays the same (so volume is not limited in any way), you can use the ideal gas law, pV = nRT. I assume an initial condition of ~20C temperature (293K). Also, I assume the temperature you're giving is in degrees F. 35000F = 19427C. If the above assumptions are correct, air will expand 19427 / 293 = 66.3 times its' initial volume.

Does a high rating mean lots of insulation or little insulation?

It depends what you mean by a 'high rating'!

If you mean a high 'voltage rating' then, yes, you will require thicker insulation. But if you mean a high 'power rating', then, not necessarily, because the voltage can be low, while the current is high.

Remember, the thickness of insulation depends on the voltage, while the type of insulation (how it withstands higher temperatures) depends on the current.

What size gas engine to run 35 kw generator?

At 746 watts per horsepower (electric) a 35 kw generator would require about 470 horsepower. Round that up, and allowing for control loop margin and mechanical losses, I would guess that a 35 kw generator should need a 500 or 600 horsepower engine.

What is the difference between planar transformer and AA normal transformer?

I am currently designing a planar transformer for a switch-mode power supply. From what I understand, planar transformer is better than a normal transformer due to its shape. It utilises flat E ferrite cores and winding tracks which saves space and is more compact for a power supply. It also has lower leakage inductance which makes it more efficient.

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