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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
Do load devices operate independently?
Perhaps, or perhaps not. Your question is not specific enough.
As a general rule, each load device demands it's required service. The perhaps not may involve load devices that communicate with each other.
Why laminations are used for iron parts of a dc machine?
Laminations minimize eddy currents, or current flow across the iron parts. This is one method to minimze stray losses.
What is ampere's law statement?
Ampere's Law, which is also known as the Ampere-LaPlace Law, relates electrical and mechanical phenomena by quantifying the force between two, parallel, current-carrying conductors in free space (i.e. in a vacuum).
Its precise statement involves an equation that utilises various Greek symbols, which cannot be expressed here as far as I am aware -so, I suggest checking it out elsewhere on the Internet.
Ampere's Law, therefore, leads to the SI definition of the ampere, which states that an ampere is 'that constant current which, if maintained in two straight parallel conductors of infinite length, placed one metre apart in a vacuum, will develop between them a force equal to 2 x 10-7 newtons per metre length'.
Can you use a transformer to convert modified sine wave to pure sine wave?
we cannot use transformer because transformer cannot change frequency . . .
Can fet be used as a transisitors?
No. The Field Effect Transistor is a different technology than the Bipolar Junction Transistor. That cannot substitute for one another.
In a 480 volt wye connection you obtain two voltages, 277/480 volts. Any leg to grounded wye point will give you 277 volts. Between any of the legs to each other you will receive 480 volts. Any two legs of a three phase system is classified as single phase supply. From a 480 volt central distribution panel install a two pole breaker sized to the amperage shown on the welding machine. Be sure to use the input current and not the output current to find the correct feeder for the unit.
Why does the rpm of a three phase motor decrease as the number of poles increase?
The synchronous speed is 6000 divided by the number of poles for a synchronous motor on 50 Hz, and 5-10% less than that for an induction motor. On a 60 Hz supply these speeds are 20% higher.
What is the duration of a pure sinusoidal signal?
A true pure sinusoid signal lasts forever, from -infinity to +infinity. If it ever turned on or off it would not be a pure single frequency sinusoid signal. Real signals aren't pure.
How do you control rpm of single phase motor without using variable frequency drive?
By changing the voltage through a potentiometer ( eg fan regulator )
How do you convert vrms to vpp?
Vrms = Vpp/squareroot(2)
This can be written another way:
Vrms * squareroot(2) = Vpp
AnswerThe question asks for the relationship between the rms value of voltage, and the peak-to-peak value of voltage, not the peak value (Vmax) of voltage, so:
Vp-p = 2 Vmax = 2(1.414) Vrms = 2.828 Vrms
What can happen if you use a 440 vac capacitor instead of a 370 vac?
You can always use a higher voltage rated capacitor, it will probably just last a little longer.
The question makes no sense. It asks why a pure inductive load is used ... instead of a pure inductive load. Please restate the question.
What will be happen if you use earthing in place of neutral in any circuit?
* * * DANGER * * * DANGER * * * DANGER * * *
Do not, under any circumstances, use earth ground instead of neutral in a circuit. Besides being a violation of the US National Electrical Code, and probably the applicable electrical code for any country that has an existing neutral system in place, it constitutes a hazard because the earth ground conductor is not rated to carry operational current. It is only there to carry momentary fault current so as to trip the protective device (fuse or circuit breaker) in the distribution panel. Also, placing operational current on protective earth ground can raise the voltage on that conductor, creating the potential for an electrocution hazard.
What happens if neutral of three phase four wire system is break?
For a balanced three-phase load, the neutral current is zero, so the loss of the neutral would have no effect.
However, for an unbalanced load, the 'difference' between the line currents results in a neutral current.
So, for an unbalanced load, if no neutral current can flow, then the load's neutral point will no longer remain symmetrical, and the line voltages will become unbalanced. If the unbalance is severe, then individual loads may be subject to over-voltages or under-voltages.
What is the voltage of a 3 phase 4 wire 277 volt lighting circuit?
The voltage of 277 volts is the wye of a three phase 480 volt system. Just as the voltage of 347 is the wye voltage of a three phase 600 volt system. To obtain these voltages for any three phase system, take the three phase voltage and divide it by 1.73. 480/1.73 = 277 volts, 600/1.73 = 347 volts.
What is the value of capacitor voltage and current after 5 time constant?
After 5 time constants, capacitor voltage/current will be about 99.3% of the input step change.
I believe the NEC specifies 125% of the continous load plus 100% of the intermittent load. Depending on the specifics of your situation this may not be correct ( a different part of the NEC should be referenced).
What is narrow bandwidth antenna?
An antenna (or aerial) is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver. In transmission, a radio transmitter applies an oscillating radio frequency electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of an electromagnetic wave in order to produce a tiny voltage at its terminals, that is applied to a receiver to be amplified. An antenna can be used for both transmitting and receiving.
Antennas are essential components of all equipment that uses radio. They are used in systems such as radio broadcasting, broadcast television, two-way radio, communications receivers, radar, cell phones, and satellite communications, as well as other devices such as garage door openers, wireless microphones, bluetooth enabled devices, wireless computer networks, baby monitors, and RFID tags on merchandise.
Typically an antenna consists of an arrangement of metallic conductors ("elements"), electrically connected (often through a transmission line) to the receiver or transmitter. An oscillating current of electrons forced through the antenna by a transmitter will create an oscillating magnetic field around the antenna elements, while the charge of the electrons also creates an oscillating electric field along the elements. These time-varying fields radiate away from the antenna into space as a moving electromagnetic field wave. Conversely, during reception, the oscillating electric and magnetic fields of an incoming radio wave exert force on the electrons in the antenna elements, causing them to move back and forth, creating oscillating currents in the antenna.
Antennas may also contain reflective or directive elements or surfaces not connected to the transmitter or receiver, such as parasitic elements, parabolic reflectors or horns, which serve to direct the radio waves into a beam or other desired radiation pattern. Antennas can be designed to transmit or receive radio waves in all directions equally (omnidirectional antennas), or transmit them in a beam in a particular direction, and receive from that one direction only (directional or high gain antennas).
The first antennas were built in 1888 by German physicist Heinrich Hertz in his pioneering experiments to prove the existence of electromagnetic waves predicted by the theory of James Clerk Maxwell. Hertz placed dipole antennas at the focal point of parabolic reflectors for both transmitting and receiving.
Does a 3 phase motor starter with a 120 volt coil need a neutral to the coil?
Usually for this type of installation there is a control transformer installed in the starter enclosure. The primary of the transformer is the motors line voltage and the secondary is the control voltage which is usually 120 volts. In Canada the control transformer needs fusing on the secondary side of the transformer. In the US the transformer needs fusing on the primary and secondary sides of the transformer. The secondary side of the transformer's terminals are labeled X1 and X2. The X2 lead is grounded to the starter's enclosure. From this point out the wire is then termed the circuit's neutral wire. This wire then connects to one side of the magnetic starters draw in coil.
Yes, 120 volt coil would require a neutral, this could be derived from the control transformer if it has one or from an external source.
Why autotransformers are not safe for supplying low voltage from a high voltage source?
Autotransformers are absolutely safe when supplying a lower voltage load from a higher voltage source, and are used to do so. However, they do not provide isolation. If isolation is considered essential, then autotransformers are not appropriate.
No such resistor exists. Any resistor placed in parallel with a 6.0 ohm resistor is going to reduce the combined resistance below 6.0 ohms.
How does the low-voltage circuit controls the power to the high-voltage circuit?
Through a relay or some other kind of high voltage switching device.
How will a shunt generator behave if the field resistance is greater than the critical resistance?
the shunt generator wont be started .hehe
