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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
For all the punks out there.for you what is a real punk?
Someone who doesn't ask what the definition of punk is lol jk Punk to me is having the mind of a rebellious misunderstood teenager for the rest of your life.
The current gain in CE mode called as beta (ß)
Tha current gain in CB mode called as alpha (A)
ß= A/(1-A)
=0.98/(1-0.98)
=49
the current gain is 49 in CE mode
Indirect method of testing of dc machine?
Losses are measured separately in this method, and efficiency at any desired load is predetermined. The iron and friction losses can be determined by measuring the input to the machine at no-load. The machine is run as a motor at normal voltage and speed. The copper losses are calculated from measured values of the various resistances. This method is only applicable to level compounded and shunt motors. Figure 5.29shows the circuit diagram of Swinburne's test.
Figure 5.29 Swinburne's Test
Let Vt be the supply voltage, I0 be the input armature current at no-load(measured by ammeter A1) andIsh be the shunt field current(measured by ammeter A2) for Figure 5.29.
Therefore, no-load armature current (Ia0) = I0 - Ish, no-load input = VtI0 W, power input to the armature = Vt (I0 - Ish) W and power input to shunt = VtIsh W.
Who is more efficient dc motor or ac motor and why?
DC motors are generally more efficient than AC motors. DC motors have a lower amount of inertial associated with them, making them more efficient to run.
Do you need a ballast for every type of HID bulb?
All high-intensity discharge (HID) bulbs, and all fluorescent bulbs, require a ballast, which is a device that limits current. It can raise the voltage and/or heat the bulb cathodes.
What is the difference between AC and DC average rms and peak values?
RMS minus ripple current , that is alternating current (sinusoidal wave form )it is including ripple voltage and ripple current . peak current is maximum peak in sinusoidal wave form . general used in choke (filter ) design calculation .
AnswerHow do you compare the 'speed' of a circular saw with that of a reciprocating saw? One spins, while the other goes up and down. The answer is that you compare them, not in terms of their individual speeds, but in terms of their 'cutting speeds' (i.e. how fast they cut board).
We do the same thing with a.c. and d.c. We compare one with the other in terms of the 'work' they do. So, for example, a 10-A (r.m.s.) a.c current will do precisely the same amount of work as a 10-A d.c. current.
So the r.m.s. value of an a.c. current is exactly equivalent to the value of a d.c. current that will achieve the same amount of work. Because voltage is proportional to current, the r.m.s. value of an a.c. voltage and a d.c. voltage are also equivalent to each other.
For a sinusoidal a.c. current or voltage, the r.m.s. value is 0.707 times the peak value.
If you're asking about load sizing, I think you already have the answer (at least 150A, although you could go up to 208 for full load, and maybe higher if you can overload the transformer). If you're talking about short circuit rating, you have entirely the wrong information. Short circuit rating will tell you if the fuse (if you're using fusing) mounting is rated to interrupt the available fault current.
What is a subwafer loudspeaker?
A sub-woofer is a loudspeaker that produces extreme low tones that other speakers cannot
Where is the starter motor on a 2002 Subaru Forester?
Look at the rear lower section of engine
Follow the + battery cable
What is Function address 0x4f4be01f caused a protection fault?
this can happen due to driver corruption...try changing the driver
What device used to increase or decrease DC voltage?
A DC-to-DC converter is the general term for a device that changes DC voltage at one level to another.
How does back emf affect starter motors?
Actually when the permanent coil dc motor rotates in magnet field by providing current an emf is induced in coil in the opposite direction of current in the coil by faraway law. this result in a torque in opposite direction.
for example he the applied voltage is 10volts and the resistance is 10ohms theories current would be 10A. it is at time is zero it means when the switched is just on or circuit is just closed.
if the induced emf is 10volts them the effective voltage will be 90volts. now he we calculate the current by ohms law the current will be 9A. This shows that at time is equal to zero the naughty current is passing through coil as the time pass amount of current passing through the coil will become less or minimum. As current and force are direct related the torque will become minimum. here the angular acceleration is decreasing it is not retarded.
-:D
In ohms what is the electrical resistance of water?
To figure the resistance of a substance in ohms, more information would be needed. Resistance is calculated by (resistivity)*(length)/(cross sectional area).
First consider a wire conductor. Electrical resistivity is a property of the substance (it usually will vary with temperature). The thicker a wire is (larger cross sectional area) will lower the resistance. The longer the wire will increase the resistance. Now consider water. There is no 'wire' so the cross sectional area of whatever conductor is in contact with the wire will be a factor. A second conductor will need to be in contact with the water to complete the current path. The distance between the conductors is the length. Resistivity has a unit of ohms*meters; when divided by area and multiplied by length, the resulting unit is ohms. The reciprocal of resistivity is conductivity, which has units of Siemens/meter (Siemens is equivalent to 1/Ohms) I have posted a link to the Wikipedia article, listing conductivity values for several conducting elements (and water as well).
Pure water with no impurities actually has a very high resistivity (low conductivity, which means not much current will flow). Pure water is not very common, and the type and amount of impurities affects the conductivity of the water sample.
Conductivity of typical drinking water is in the range: 0.0005 to 0.05 Siemens per meter, so the reciprocal (resistivity) is 2000 Ohm*meters to 20 Ohm*meters. Note from the same chart that deionized water has a conductivity of 5.5 × 10-6 Siemens/meter --> resistivity = 181,818 ohm*meters.
If you are being billed for kVA or a percentage of kVA as opposed to kW then installing power factor correction equipment will reduce the kVA demand. To determine if this is cost effective is the challenge which I specialize in. Email me at mark@epowerfactor.com
How much torque is required to pop a party popper with a DC motor?
Party poppers are normally popped with a force applied by a finger. The force required is maybe 10 Newtons.
How electrical ground on ship works?
water is the ground for ships ,and the salt water is the best conductor and it acts as a zero potential(like for us ground as) for ships.
that would be good for the cold idle and should drop three times as the car warms up and should idle about 650 to 800 auto trans
How do you charge a capacitor?
You charge a capacitor by placing DC voltage across its terminal leads. Make sure when using a polarized capacitor to place positive voltage across the positive lead (the longer lead) and negative voltage across the negative lead.
Also make sure that the voltage you charge the capacitor to doesn't exceeds its voltage rating.
What is the difference between kw and kva on a 1000w panel heater?
KW is a measure of real power (kilo watts) used. Real power is the power disippated / transformed into heat (in your instance). KVA (kilo volt amperes) is a measure of the vector total of real power and reactive power used. Reactive power is power that is stored and released be certain electrical elements such as capacitors and inductors. A heater inherently has a certain amount of inductance due to the heating wire used, which appears as an inductor to the 60Hz AC voltage applied to it. KW is a useful term because this is how much power you are using. KVA is useful, because this defines the total current draw your heater will have, so wiring and fusing need to be sized accordingly.
Why we can't store alternating current?
Not quite sure what you mean; a current, by definition, is a flow of electric charges. You can convert electrical energy to some other type of energy, and store the ENERGY, which can then be converted back later (there will always be some losses, of course), but it isn't clear what you mean by "store electrical current".
Why the air gap between stator and armature of electric motor is kept small?
Obviously, if there wasn't a gap, the rotor would not be able to rotate! However, the gap should be as small as possible in order to minimise the reluctance of the magnetic circuit (reluctance is equivalent to resistance), because the reluctance of air is very much larger than for silicon steel.
i dnt know wats the answer
What is the use of active power filters?
An active filter is a type of analog electronic filter that uses active components such as an amplifier. Amplifiers included in a filter design can be used to improve the performance and predictability of a filter, while avoiding the need for inductors (which are typically expensive compared to other components). An amplifier prevents the load impedance of the following stage from affecting the characteristics of the filter. An active filter can have complex poles and zeros without using a bulky or expensive inductor.
