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
Yes. Stationary electric (electrostatic) fields will act on each other and a force will be developed. If you had a standing electric field and could "beam in" an electron (a la Star Trek), the electron would react at once and move either toward a positive field source or away from a negative field source. The electron would know the field was there the instant it appeared.
Calculate copper losses at 75c?
Copper Loss at 75 C = Copper Loss at Ambient Temperature C * (310/(235+Ambient Temperature C))
For a transmission line the characteristic impedance with inductance 0.294mHm and capacitance 60pFm?
= Zo = sqrt(L/C) = sqrt(0.294e-3/60e-12) ~ 2214 ohms =
What is the conversion for rms voltage to peak to peak voltage?
For sine waves:
To calculate the RMS value of a sine wave, multiply the peak value by 0.707. The peak value is, of course, one half the peak-to-peak value. To go the other way, reverse the order of operations. That is, if you're starting with an RMS value, divide by 0.707 and then multiply by two to get the p-p value. Another way to convert from RMS to p-p is to multiply the RMS value by two square roots of two: RMS x 2 x SQR(2).
Or more simply, to convert from RMS to peak to peak voltage:
(RMS x 1.414) x 2=P-P
For example:
120vac x 1.414= 170vac
169.68vac x 2 = 339.36vac P-P
Where there is a significant reactive component in the characteristic of the cabling or load, we must also consider the effects of the X/R ratio. The real vs imaginary components of the impedance:
V(peak) = V(rms) * sqrt(2) * (1+ e(exp -pi/(X/R)))
where "exp" is the exponent to which the value of e is raised.
Reading the power of e above in English:
"e to the power of (minus pi divided by the X/R ratio)".
Take careful note of the top line of the first answer "For sine waves". More specifically the formula applies only to a signal which is a pure sine wave (a single frequency, no harmonics or other frequencies). As soon as you combine two or more sine wave signals of different frequencies, the ratio of peak voltage to RMS voltage depends strongly on the phases of the component signals. Too complicated to answer here, in full explanation.
Vrms = (Vp-p / 2 )/ sq.root (2) = Vp-p / 2.828 for sinusoidal waves..
*Note: If the signal or the waveform is not sinusoidal you'll have to derive from basic steps with a sound knowledge about integrations.
RMS = root mean square = square root (mean(square values of voltages))
What is the likelihood of an oil-filled transformer exploding as a percentage?
? This cannot be easily quantified. transformers normally fail due to excessive through fault current. This does not mean that all transformers that fail explode - most do not, for good reason. An exploding transformer is a danger to anyone in the area. Some oil filled transformers are huge (several hundred tons). Protective devices usually operate fast enough to keep catastrophic failures like you're looking for from happening.
If the protection fails to clear faults fast enough, can happen. So the percentage of failures really does not have to do with the transformer (oil filled, gas, whatever kind of transformer) as much as with the protection implemented for that transformer.
I've seen two large transformer failures; neither resulted in an explosion. I've also seen an oil filled breaker fail (as a result of incorrect protection), and it did explode. It totalled a vehicle several hundred feet away.
So... I'll say "1 in a million" or .0001% would probably be a good, totally unqaulifiable answer.
Transformers are rated in what?
Transformers are rated in KVA. (this is because the transformer is Unity power factor device i.e.. PF = 1)
AnswerThe selection of a transformer is determined by the apparent power of the load, expressed in volt amperes(V.A), the load current, and the line voltage of the supply. The transformer must be able to satisfy these requirements.
Transformers are not 'unity power factor' devices, which is precisely why their capacity is expressed in volt amperes, rather than in watts.
Which dc motor gives above 20kg torque?
torque is not measured in mass units
20kg force = 20kg * 9.8meters/sec/sec
or 20Newtons
ive seen torque wrenches in kg-meters as well as newton-meters and foot-pounds
a pound is 32.2 slug feet/sec/sec
most power drills have dc motors if you get one with a large chuck 3/4" or so
it will have 20kg meter or 400ft lb ( brand name holehog for example)
older locomotives have dc motors on each axle usually about a 1-1 ratio gearing
300-500Hp for each motor
newer locomotives can use ac motors with the advent of variable frequency ac drives - although it takes a bit more power to achieve the same starting torque
Can ac pass through capacitor?
AC can pass through a capacitor. The higher the frequency of AC the lower the reactance (like resistance). The current and applied voltage are 90 degrees out of phase the current leading the voltage by this amount.
(Electronics) Resistor placed in the emitter lead of a transistor circuit to minimize the effects of temperature on the emitter-base junction resistance and its resistance is called swamping resistance.
What are the different generating voltages?
it varies from power station to power station in vtps we have 15.75 kv
If you are saying that the Zeners are connected in series, the answer is Yes.
The answer you need is found in "Ohms Law." It is expressed like this: Current = watts divided by volts Watts = Volts multiplied by current Volts = Watts divided by current. I recommend you look into the hobby of Amateur Radio and put your knowledge of electronics to a fun use. My wife and I are both 'hams' and love the hobby!
What steps to be taken before synchronising two ac generators?
The basic run up checks should be made, and then the generator coming onto the grid that the first generator is on is brought up to speed. The operator runs up the rpm's of the generator coming online so it turns just a bit faster than the line frequency. Then, with the generator coming online running a bit faster than the line, the operator watches the phase relationship of the generator with the line. The indicator on the meter will be moving like a second hand on a clock, only faster. Maybe one cycle every half dozen seconds or so. As the phase indicator is coming up on 0 degrees (or 360 degrees, or "straight up" on the indicator), the operator actuates the breaker lever to close the breaker and parallel the machines. One rule of thumb is to shut the tie at "5 'til the hour" on the indicator. The idea is to get the machine coming online up to speed an running a tad faster than the line, and then shutting the tie when the oncoming machine is amost but not quite in phase with the line, but is a bit "ahead" of the line by a small margin. That gives the tie a second or so to close, and the machines will be "pretty close" to being in phase when the tie goes shut. The machines will then lock as soon as the connection is made, and the operator will then run up the field voltage in the oncoming generator to get it to assume more of the load on the line. He will balance the loads, or otherwise shift them, perhaps with the idea of taking the first generator off line.
Why should you NOT repair heating elements by soldering?
The solder will most likely melt at the operating temperature of the heater.
- electric motor
- relay coil
- speaker coil
- speedup coil (in vacuum tube or discrete transistor digital logic)
- etc.
What are the three major phases in mintzbergs incremental decision process model?
Identification phase which begins with recognition. The development phase where a solution is shaped to solve the problem and the selection phase when the solution is chosen.
What are the Advantages of amorphous core for a transformer?
The following advantages are there:
1. Low hysteresis losses
2. Low eddy current losses
3. Skin-effect in core is low
Where can you find a manual for the Power Rider?
Unfortunately, the Braun Company (who used to sell the Power Rider), has gone out of business. The good news is that the Power Rider is quite a bit like the Cardio Glide which is made by Weslo. You can find a manual on their website for around $2. Here is another opinion: Guthy-Renker manufactured Power Riders. Fran Tarkenton was the spokesperson for this product. They didn't go out of business. They just stopped manufacturing this piece of exercise equipment (they now are involved in other products such as ProActiv Solution and Daisy Fuentes' exercise system). To contact Guthy-Renker and see if they can get you a video: Guthy-Renker Corporate Headquarters 41-550 Eclectic Street Suite 200 Palm Desert, CA 92260 Phone: 760-773-9022 Fax: 760-773-9016 Or send an e-mail to: customerservice@guthy-renker.com And more input: * I think you'll find the manual to be pretty unhelpful I'm afraid. You really need to get a hold of the video that comes with the machine.
CK THE ASD RELAY IN THE FUSE BOX UNDER THE HOOD-SWITCH IT WITH THE A/C RELAY TO SEE IF THE CAR STARTS ON ITS OWN-
