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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
How do you calculate the current capacity of a cable when the cable size is known?
The current-carrying capacity of a cable depends on a number of things in addition to its cross-sectional area; these include the type of conductor, number of cores, type of insulation, whether or not it is armoured, method of installation, etc. Accordingly, to determine its current-carrying capacity, you will need to refer to your national electrical code. For example, in the UK, BS 7671:2008 Requirements for Electrical Installations contains tables for all standard cable types, specifying current-carrying capacity, voltage drops, etc.
Why elevators run on direct current?
One of the requirements of an elevator is high speed between floors, but a slow speed as it approached the floor, so that the floor levels are accurately aligned.
This is easy to organize with a DC motor.
BPL modems use silicon chipsets specially designed to handle the work load of pulling data out of an electric current. Using specially developed modulation techniques and adaptive algorithms, BPL modems are capable of handling powerline noise on a wide spectrum.
[quote]http://static.howstuffworks.com/gif/bpl-modem.gif[/quote]
The BPL modem simply plugs into the wall and then into your computer. These modems are capable of speeds comparable to DSL or cable modems.
A BPL modem is plug and play and is roughly the size of a common power adapter. It plugs into a common wall socket, and an Ethernet cable running to your computer finishes the connection. Wireless versions are also available. While the potential of this new technology is exciting, not everyone is excited about it. In the next section, we'll discuss some of the challenges confronting the implementation of BPL.
On April 23, 2003, the FCC put forth a Notice of Inquiry to the public supporting the potential of the BPL technology and seeking to set standards in practice for its implementation. Immediate opposition came from the American Radio Relay League (ARRL) and the Federal Emergency Management Agency (FEMA). Both entities claim that BPL will cause serious interference issues. A BPL modem is considered an unlicensed device, like a cordless phone or garage door opener. All unlicensed devices are governed by the FCC's Part 15 rules. Part 15 mandates that all electronic devices sold in the United States must meet FCC radio-frequency emissions limits. These limits are in place to secure against interference with important transmissions like CB communications, air-traffic control and government channels. ARRL and FEMA are concerned about the interference caused by BPL signals transmitted on exposed medium-voltage power lines. Cable TV operators get around the interference problem by shielding all of their cables. "Coaxial cable" used by cable TV operators has a braided metal shield that surrounds the signal wire. Telephone cables are also shielded. Power lines, on the other hand, have no shielding. In many cases, a power line is a bare wire, or a wire coated in plastic. The lack of shielding is where the interference concern comes from. Depending on the bandwidth the FCC allots for BPL, interference with other radio services may be a problem. Currently, the frequency band breaks down as follows:
[quote]http://static.howstuffworks.com/gif/radio-spectrum.gif[/quote] * AM radio - 535 kilohertz to 1.7 megahertz * Short-wave radio - 5.9 megahertz to 26.1 megahertz * Citizens-band (CB) radio - 26.96 megahertz to 27.41 megahertz * Television stations - 54 to 88 megahertz for channels 2 through 6 * FM radio - 88 megahertz to 108 megahertz * Television stations - 174 to 220 megahertz for channels 7 through 13 While FEMA is wiling to allow the FCC to seek a compromise, the ARRL claims that compromise is not possible because the bandwidth needed for BPL will directly interfere with ham radio and short-wave radio transmissions. Developers of BPL say that these interference issues have been solved. Only tests and time will tell. Until then, the advancement of BPL moves forward slowly as it waits for standards and logistics to be decided by regulating bodies. For more information on BPL, other Internet connection methods, and related topics, check out the links on the next page.
If 3 resistors of 56 12 and 33 ohms are in parallel what is there combined resistance?
The combined resistance is 7.6049 ohms.
126 volts sounds very close to a standard home voltage of 120 volts, which is single phase. 208v is a three phase voltage, and is the lowest I have seen. 240 is single phase (usually center tapped, so in your house you have +120, and -120 referenced to the neutral which provides the normal 240 for dryers, stoves, etc.).
Potential difference is measured in a unit called 1 a volt 2 a Watt 3 an Ampere 4 an ohm?
The answer is volt.
For a thermodynamic system the COP is 5 and the heat supplied to the system is 1 KW?
This looks like the beginning of a question - but it never gets around to the question. Without a question being asked, it's pretty hard to provide an answer.
For the benefit of anyone who stumbles upon this non-question, I'm guessing that they might have been looking for the work required to supply 1 KW of heat to the reservoir of a system where the COP is 5.
COP is the acronym for "coefficient of performance". It is defined as COP = Q/W where Q is the heat supplied to or removed from the reservoir. If Q is 1kw and the COP is 5, then it would take W = Q/COP = 1 kW/5 = 0.2 kW of work to supply that heat.
A load with a poor power factor draws extra current from the power supply, meaning that there will be more of a voltage-drop in the supply.
As an example, if the load is 6 kW on a 240 v supply, the current drawn is 25 amps if the load has a power factor of 1. The kVA is equal to the kW.
But if the load has a power factor of 0.8 it needs to draw 7.5 kVA for a power of 6 kW, which is a current of 31.25 amps, so there is more of a demand on the power supply wiring etc. The transmission losses increase by 56% with the extra current.
In both cases the customer is charged for power used, 6 kW. That is why the supply companies do not like loads with a poor power factor and sometimes charge commercial customers more for a poor power factor.
That in turn makes it viable for the customers to correct the power factor of the load they place on the supply.
How can noise be converted into electrical energy?
Audio frequency is converted into electrical pulse, with the help of a diaphragm
vibrating depending upon the electomagnetic pulses.
Whats meant by radial magnetic field?
A radial magnetic field ensures that the plane of the coil (rotating within the magnetic field, in say a DC motor) is always flat within the external magnetic field ensuring maximum torque in (nearly) all positions.
Hope this helps!
What motor is used for running lathe spindle?
Single phase induction motor ( usually capacitor- start type)
If voltage equals resistance x current then?
Ohm's Law: Voltage equals Resistance times Current Given any two, you can figure out the other using simple algebra.
Can you connect batteries in series and parallel?
Yes, series and parallel connection of batteries is possible.
When connected in series Voltage increases.
In parallel, Current increases but voltage is constant.
How is electricity distributed in Singapore?
In Singapore, a transmission company - SP PowerAssets - owns and manages the national electricity transmission system
How many types of pulse width modulation techniques are there?
as many as there are ways to place points on a line segment
Is a minor in Robotics and mechatronics good if you are majoring in Computer Engineering?
Definitely. That robotics course is going to help you get more involved and learn more lower-level sort of stuff for that Computer Engineering Course.
What are you increasing by using more batteries?
technically speaking all you do is increase the voltage if the batteries are ran in a series circut and you increase amperage if they are ran in a paralell circut
What is the best university in electrical power engineering in Germany?
RWTH Aacehn University, Technical University Munich, Technical University Darmstadt.
Most accurately you would say that the mechanical energy that drives circulation is?
ventricular contraction, page 560 :)
Active Power is a company that designs and manufactures backup power systems. Power systems that can keep an operation running during outages or other issues are critical to production.
How can pulleys be used to increase the speed of a motor?
I dont think you can increase the speed of the motor but if the motor is driving some piece of rotating equipment (pump etc) the speed of the driven shaft can be increased up to the point where the motor reaches full load current.
What should the value of the resistance box for a 5 hp slipring induction motor?
its depends upon rotor voltage and current
