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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
Will the resistance of a copper conductor decrease with an increase in the applied voltage?
If all environmental conditions remain constant then the resistance will not change appreciably with applied voltage, but the current will increase. An increase in current will raise the temperature of the conductor which will increase the resistance somewhat.
the reason one needs to remove metal from one's hands(including fingers or wrist area) is that a circuit can be made if the metal comes in contact with the circuit parts. if this happens, a circuit could be made through the jewelry and the jewelry would then be carrying voltage and/or current which of course, would be attached to the person wearing it! This would be a short circuit causing damage to the circuit, and also to the person wearing the jewelry...so watch out!
What is the function of a combination pliers in an electric circuit?
for made of electric circuit
safety device,
I can't answer for fossil (high pressure) cycles, but for the Nuclear Steam Supply Cycle (intermediate pressure) the efficiency is about 33%.
Generator Transformer back-charging is done because of the following reasons:-
1. To ensure the healthiness of Generator transformer after performing all the transformer related tests before synchronising with the grid.
2. To ensure all the protections of transformer before putting it into actual operation.
3. To check the polarity, ratio & connections of transformer.
4. To check all the PTs & CTs in circuit & their availability to the relays for protection & metering.
5. To check Voltage level & polarity at LAPT.
6. To perform change-over operation checks of UATs & the tie breakers with main breakers.
Since all the protection system related to relays acts in the same way for forward & reverse power, we check the availabilty of each equipment before final synchronisation with the grid.
EE2203 Electronic devices and circuits question Bank?
how can i get 2203: electronic device and circuit question bank in B.E.-E.E.E. 2nd for Anna university chennai
25 thousand volts
According to Ohm's law if V is constant?
Ohm's Law describes the relationship between the voltage (potential difference) across the ends of some conductors and the resulting current through those conductors for variations in voltage. If the voltage is constant, then Ohm's Law is irrelevant.
Will 351 modified 4 speed transmission fit 351 windsor motor?
No a 351/400 is the same as the 429/460 Big block style, the 351W is the small block motor style like the 289, 302, 351C, 300 I-6. If the bell housing unbolts from the housing find the small bolt patter to match the tranny.
In how many different modes a universal shift register operates?
HOW many mode sdo a universal shift register operates
Before making any changes to circuit breakers, make certain that the breaker does not exceed the capacity of ANY current carrying wire in the circuit.
If you attempt to increase the size of the breaker in your condo, and exceed the capacity of the wire that is fed from that breaker, you WILL burn down the condo and when the fire department investigates the fire and finds out what you did, the association will be quite upset with you.
Plus, it's against the law.
If you need to make that kind of change to your electrical wiring, contact a qualified electrician to discuss options.
You will also need approval of the Condo Association in most situations like this.
black black brown black is just some fool's uneducated guess.
The correct answer is:
Brown, black, gold which translates to 1,0 x point 1
or 10/1 = 1ohm
Look at http://www.hobby-hour.com/electronics/1ohm-8ohm2-resistors.php for more.
What type of motor is used in dam gates?
Generally for big and major dams,motors are alone not used,all this type dam gates will be controlled manually.Because it is not easy to conrol the large dam gates by motors.
But for the dams with single gates,used for irrigation purpose,in canals,we can use the synchronous reversible motors to control such type of dams.
If you are talking about the primary wires to the transformer then yes they have to be encased in concrete.
KVA is a measure of power, while amp (or ampere) is a measure of current.
KVA meanes kiloVoltAmps. 1 kVA = 1000 V*A.
so 225 KVA = 225,000 VA (volts * amperes)
So you would need to also know the voltage, in order to find the amperes.
Does an airplane have a motor?
Yes, airplanes do have a motor (according to what I know). There are many place in a commercial aircraft that have a motor. The engines also have a motor in them to turn the fan or propellers.
What is the horsepower rating of an electric motor?
Horsepower is the Imperial unit of measurement for power. In North America, the horsepower is still used to define the rated output power of a motor, whereas the watt is used to define its corresponding input power. Because no device is 100% efficient, a motor's rated output power is always lower than its corresponding input power.
Elsewhere in the world, horsepower is considered to be an obsolete unit of measurement and, so, the watt is used to define both the rated output power and the corresponding input power.
In its simplest use a resistor in a circuit is used to limit the amount of current flow, or to decrease the amount of voltage applied to a device. One example is you had a 12 volt battery and you need/ wanted to connect it to a device that ran on 9 volts then a resistor can be chosen to reduce the 12 volts to the 9 volts required.
What is use of slack bus in ac power flow and dc power flow sepratly?
For make a system balanced
losses in power
First you have to check and conform there is no earth leakage in your home.
Then conform the earth is perfect. then check the P-N , P-E and N-E voltage.
If the P-N voltage is less than that of P-E voltage, problem is IMPROPER NEUTRAL of your supply system.Means,you have to balance the load of the supply system or conform the neutral earthing in distribution transformer side by the help of Electricity board authority.
If the P-E voltage is less than that of P-N voltage , you have to strengthen your earth.
After that all above mention, you will get P-N V is almost equal to P-E V and N-E V will come around 0-3 V.
What is better-digital or analog communication?
It depends on applications. At the middle - short distances analog communication can be much more efficient than digital. If you work in communications, you may find the explanation - why? in IEEE Comm. Letters, vol.16, no. 5, 2012, pp.573-576, as well as in my Research Gates Profile. With regards.
What does L1L2L3 on a three phase motor mean?
Three phase alternating current systems are either 3-wire systems or 4-wire systems. In the case of a three-wire system, each 'wire' is properly called a line conductor. A four-wire system comprises three line conductors and a neutral conductor.
Line conductors can be identified by letters, or by colours. If they are identified by letters, they can be L1, L2, and L3, or A, B, and C, or R, S, and T -depending on the national/international standard adopted. If they are identified by colours, then these may be red, yellow, and blue, or brown, black, and grey -again, according the the national/international standard adopted.
The permanent magnet moving coil instrument is the most accurate type for D.C. Measurements. The working principle of these instruments is the same as that of the d'Arsonval type of galvanometers, the difference being that a direct reading instrument is provided with a pointer and a scale
(Fig) Permanent magnet moving coil instrument
Construction of PMMC Instruments
- The constructional features of this instrument are shown in Fig.
- The moving coil is wound with many turns of enameled or silk covered copper wire.
- The coil is mounted on rectangular aluminum former, which is pivoted on jeweled bearings.
- The coils move freely in the field of a permanent magnet.
- Most voltmeter coils are wound on metal frames to provide the required electro-magnetic damping.
- Most ammeter coils, however, are wound on non-magnetic formers, because coil turns are effectively shorted by the ammeter shunt.
- The coil itself, therefore, provides electro magnetic damping.
Magnet Systems
- Old style magnet system consisted of relatively long U shaped permanent magnets having soft iron pole pieces.
- Owing to development of materials like Alcomax and Alnico, which have a high co-ercive force, it is possible to use smaller magnet lengths and high field intensities.
- The flux densities used in PMIMC instruments vary from 0.1 Wb/m to 1 Wb/m.
Control
- When the coil is supported between two jewel bearings two phosphor bronze hairsprings provide the control torque.
- These springs also serve to lead current in and out of the coil. The control torque is provided by the ribbon suspension as shown.
- This method is comparatively new and is claimed to be advantageous as it eliminates bearing friction.
Damping
- Damping torque is produced by movement of the aluminium former moving in the magnetic field of the permanent magnet.
Pointer and Scale
- The pointer is carried by the spindle and moves over a graduated scale.
- The pointer is of lightweight construction and, apart from those used in some inexpensive instruments has the section over the scale twisted to form a fine blade.
- This helps to reduce parallax errors in the reading of the scale. When the coil is supported between two jewel bearings two phosphor bronze hairsprings provide the control torque.
- These springs also serve to lead current in and out of the coil.
Torque Equation.
The torque equation of a moving coil instrument is given by
As the deflection is directly proportional to the current passing through the meter (K and G being constants) we get a uniform (linear) scale for the instrument.
Errors in PMMC Instruments
The main sources of errors in moving coil instruments are due to
- Weakening of permanent magnets due to ageing at temperature effects.
- Weakening of springs due to ageing and temperature effects.
- Change of resistance of the moving coil with temperature.
Advantages and Disadvantages of PMMC Instruments
The main advantages of PMMC instruments are
- The scale is uniformly divided.
- The power consumption is very low
- The torque-weight ratio is high which gives a high accuracy. The accuracy is of the order of generally 2 percent of full-scale deflection.
- Using different values for shunts and multipliers may use a single instrument for many different current and voltage ranges.
- Since the operating forces are large on account of large flux densities, which may be as high as 0.5 Wb/m, the errors due to stray magnetic fields are small.
- Self-shielding magnets make the core magnet mechanism particularly useful in aircraft and aerospace applications.
The chief disadvantages are
- These instruments are useful only for D.C. The torque reverses if the current reverses. If the instrument is connected to a.c., the pointer cannot follow the rapid reversals and the deflection corresponds to mean torque, which is zero. Hence these instruments cannot be used for a.c.
- The cost of these instruments is higher than that of moving iron instruments.
What is your observation of resistors in series?
I observe that the total effective resistance of several resistors in series
is the sum of the individual resistance values of the individual resistors.
What is the rms current for an 8.0 µF capacitor attached to a 120 V rms 60 Hz source?
The RMS current for an 8.0 µF capacitor attached to a 120 V rms 60 Hz source is 39,798 amperes.
