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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
AMF panel is the short form of Auto Man Failure panel. It is normally connected to the generator set to control the generator set function. It can call the generator set if the AMF further connected to the Main Switch Board ( received power from the other source - normally from the local authority ) which equipped with auto transfer switch/automatic changeover contactor. While normal supply serve to main switch board failed, the AMF board will send the power failure signal to generator set. Then the generator set will run and serve the supply to main switch board.
Why a diode is connected parallel to a dc motor in its speed control circuit?
A motor is a mass of wires classified as a coil. Coils have a decency to generating reverse voltage when commutation the diode therefore is there for clipping this harmful back EMF
Why were instrument of a transformer placed on a high voltage side in short circuit test?
I assume "tension" in this question should be replaced with "voltage". Short circuit tests are often performed from the lower voltage side of the transformer, since a lower voltage source is then required to perform the test. Often times the test lab may not have a source that can output a high enough voltage to perform from the high voltage winding.
What is the importance of phase sequence?
The importance of phase sequence is related to the direction of rotation for a motor.
The three phases set up a rotating magnetic field, which runs the motor. Reverse the sequence, and most motors will run backwards, not necessarily a good thing.
There really are only two sequences; ABC, and ACB. All other sequences are permutations of one of these.
What is low voltage switchgear?
Low-voltage switchgear may be suitable for industrial or commercial use, so long as the distribution system does not exceed 600 volts.
They may either be used alone or incorporated into a larger unit for secondary monitoring of power utilization.
Be sure to always purchase switchgear from a trusted company, and research industry standard terms of use.
What happens if the synchronous motor exceeds its load capacity?
If load on a generator is greater than the generator can provide, the generator will begin to slow down. If it slows down too much, it will lose synchronism.
Why do homes and factories have different voltages?
Factories often have three phase voltage, and higher voltage (480V) compared to homes. Three phase voltage is necessary for three phase induction motors, which are often used in factories. These are very rarely used in homes. Three phase power requires more equipment than single phase (2 or three step down transformers vs. one for single phase).
Factories use higher than home voltages so wiring can be sized down and still provide the necessary power ( P = V*I ). Higher voltage equipment naturally costs more, and homes typically do not need the amount of power that would require excessively large guage wires, so it is more economical (and safer) to run lower voltage.
How many years does it take to get a master's degree in electrical engineering?
1 year apperntice 3 years joneryman then masters so 4 years
What determines the amount of voltage produced by a voltaic cell?
what determines the amount of voltage produced by a voltaic cell?
What happens if you touch an exposed electrical wire?
If the wire is carrying an electrical current, and if the current has enough voltage, the current can leave the wire and pass through your body. This is painful, and can causes burns or death.
What is the formula used to calculate electrical power in an ac circuit?
The following equation only works for a balanced three-phase load, that is, where each of the three phases is identical in all respects:
P = 1.732 VL IL x power factor, where VL and IL represent line voltage and line current, respectively.
For unbalanced loads, you must determine the power of each phase, using the following equation, and add them together to find the total power:
Pp = VP IP x power factor, where VPand IP represent phase voltage and phase current, respectively.
What is the purpose of running capacitor?
If I understand the question, a "run" capacitor is used in a squirrel-cage motor to create a phase shift in one of the windings. The result is a rotating magnetic field within the motor which causes the rotor to rotate in sympathy.
In synchronous motors, a "start" capacitor is used to create a rotating field for starting, then disconnected.
What are the amount of voltage across the diode?
The amount of (forward biased) voltage across a diode is dependent on current and temperature. A typical silicon diode has a forward voltage of about 0.6V at low current and temperature. As current goes up, voltage goes up slightly, with a typical voltage being 1.4V at high current. As temperature goes up, voltage goes down slightly, but the maximum current rating also goes down.
Split Phase Induction (Resistance Start, Capacitor Start, Capacitor Start/Capacitor run)
Three Phase Induction
Wound Rotor Motor
Synchronous Motor
Hysteresis Motor
Reluctance Motor
Selsun Motor
Consequent Pole Motor
Inside-out Motor
Stepper Motor
Amplidyne Motor
Printed Circuit Motor
Brushless DC Motor (Pulsed DC)
Universal Motor (AC or DC)
Repulsion Motor
How did georg ohm come up with the Ohm?
He did not come up with the Ohm, it was named after him many years after his death.
Where do you ground a delta delta transformer?
In a delta-delta transformer, none of the actual conductors are grounded, directly or indirectly.
You do, however, always ground the casing. This is protective earth ground, or PE ground, as opposed to neutral, which is grounded at the distribution panel, but which is a current carrying conductor. PE ground is not a current carrying conductor - it is a safety ground. Some texts use the term grounded conductor to refer to neutral, and grounding conductor to refer to PE ground. Simplest designation is neutral and ground.
In summary, for a delta-delta transformer, there is no neutral, but there is always a ground. There is always a ground in any circuit, even when there is a neutral, and, except in a few special cases, those are two different connections.
How do you convert MVA into MW?
You would have to know the Power Factor, normally designated PF. MVA x PF = MW.
If the PF is unity then MVA = MW. A PF of UNITY suggest the load is purely resistive with neither capacitive nor inductive components in the load or source. Of course this can mean such components have been balanced artificially.
Can a multimeter be used as substitute of ammeter and voltmeter why?
yes it can read both ac and dc voltage and current .
AnswerThe whole point of a multimeter is that it can perform the function of an ammeter, a voltmeter, and an ohmmeter!
How do you covert watts to amps?
Watts = current x volts, so you have to multiply Kw value by 1000 to get watts, then divide by the applied voltage. examples.
2Kw kettle (U.S) current = 2 x1000 divided by 120, or 16.7 amps
2Kw kettle (UK) current = 2 x1000 divided by 240 or 8.35 amps
100 watt car amplifier current = 100 divided by 12 volts = 8.5amps
What will happen if the transformers working in parallel are not connected with regard to polarity?
when two transformer are connected in parallel condition,and the polarity of transformer are opposite to each other then a large circulating current flow through out the winding,therefore a very small current flow thro, the load .therefore lifespan of transformer will be reduced.
Why 3 phase is 440 volts why not 660?
Because 3 phase voltage is not algebraic sum it is the vectorial sum. Vijaye Raj A.I.E.M.D
Houses are not wired for three phase power as there is typically no need for that much power. 120/240 volts is the typical home voltage. Even some vary large houses (mansions) are still the same single phase voltage, just a very large amperage service (voltage times amperage is wattage, and use is rated in wattage). Utilities charge a base rate for homes that is usually in the range of $10-$30 per month, this is the charge when no electricity is used. For a three phase service, the charge is typically $125-$250 (depending on location and utility) per month before any power is used. Most all wires installed in a house are single phase. The black and white in 2 conductor with ground NM cable are suitable for only two of the three phases. 3 conductor with ground can be used, but that is not installed unless there is a purpose for the third wire that makes it unusable for the third phase. Three phase power must be designed into the construction of the house before it can be considered for a service, and then the cost is likely too high for the average owner.
Alternative Answer
The above answer applies to North America. But in other parts of the world, three-phase supplies to residences are quite common. For example, my house, here, in Cyprus, has a three-phase service. In these cases, the consumer panel has three separate line busbars, and the residence's loads are balanced between each line.
How can electricity produce by using magnet?
Electricity is generated when a piece of conductive metal (such as copper) is passed through a magnetic field (or if the magnetic field is moved around the metal). A generator will have a copper wire in the center, surrounded by a magnet shaped like a torus (donut shaped, wire is in the hole in the middle). The wire is stationary. Electricity is generated when the magnet is spun (moving the magnetic field around the wire). This will generate an AC current (alternating current).
