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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
Some electric motors have windings enabling them to run at different speeds.
Drawing of speed-torque curve for synchronous machine?
Theoritical torque speed curve for a synchronous machine will be a vertical line located vertical to the synchrounous speed at x axis, from starting torque to stalling torque value. This is because theoritically synchronous motors are not self starting. Practically however they start as induction motors and at near synchrounous speed the excitation is switched on. Anand Sekhar
computer-based system(it contains both hard ware and software) that can process data that are incomplete or only partially correct
Fuzzy logic was introduced as an artificial intelligence technique, when it was realized that normal boolean logic would not suffice. When we make intelligent decisions, we cannot limit ourselves to "true" or "false" possibilities (boolean). We have decisions like "maybe" and other shades of gray. This is what is introduced with fuzzy logic: the ability to describe degrees of truth.
Example:
in fuel station if you stop a fuel injecting motor at 1.55897ltrs.it can be done with the help of fuzzy logic.fuzzy has a meaning like accurate.
132kV substation is part of transmission and distribution of power in which the transmission voltage is 132kV. The substation is for stepping down or stepping up of the voltages to the required voltage. the substation also serves as a place where the transmission lines can be isolated, controlled and monitored. The substation consists of different equipment that is used to regulate, monitor and distribute the required power.
Another Answer
In the UK, 132 kV voltages are considered to be the lowest transmission voltages. Other transmission voltages are 275 kV and 400 kV. A '132-kV substation' is normally one in which this voltage is stepped down to a primary distribution voltage, usually 33 kV but, sometimes, 66 kV. As the previous answer points out, substations contain transformers, switchgear, busbars, and protection equipment.
What is the different between ac dc motors?
DC Motor works on DC source and AC motor works on AC source
What value of resistance is used to convert galvanometer into voltmeter?
It depends on the resistance of the galvanometer and its full scale current. A 100 ohm meter reading 1 milliampere would require 0.1 volts to reach full scale, so it would require about 0.1 ohms in parallel to become a 1 ampere ammeter.
Why does a phase in secondary side in distribution transformer give low voltage?
transformer is busted; if input voltage is normal you have short circuit or open circuit somewhere
Can current flow both ways through a lamp?
Yes, we use AC (alternating current) in our homes, the current changes direction 120 times a second.
The normal phase of aluminum at room temperature is a solid.
You can, however, heat to really high temperatures until it becomes a liquid or even a gas.
Can you run AC and DC cables in the same conduit?
In California and I believe the NEC states " no low voltage can share conduit with high voltage". Also it's not recommend to even run "with" or alongside conduit w/ AC in it. The interference will kill you transmission speed.
Answer:
The above answer is very true. While Cat5 can intersect with AC wire at 90 degrees to the AC wiring, it should not be run parallel with it, unless it's at least a foot or so away.
If we change the polarity of capacitor in ceiling fan why it starts rotating reverse direction?
by changing the polarity of capacitor of single phase ceiling fan can we change the direction of rotation from anticlockwise to clockwise
How does identify the capacitor capacity for 1.5 kw single phase motor?
If the power factor is 0.7 the reactive power equals the real power, so the capacitor should be 1.5 kVAr. That is a reasonable estimate for a small induction motor.
What is the disadvantages of using auto transformers?
there can be a lot of leakage flux in auto transformer. because primary and secondary winding in auto transformer is not separated.
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There is no primary to secondary isolation.
Current rating is limited to the size of the conductor used for the entire winding.
And also With an autotransformer, there is a absolute electrical affiliation from primary to secondary. It is generally the case that the anterior coupling that exists with accustomed two-winding transformers is a big advantage that would not be had with an autotransformer. For example, an autotransformer added readily couples voltage transients from one voltage to the other; with two-winding transformers, voltage transients are accompanying by the capacitive voltage affiliate aftereffect and may be suppressed.
A transformer is an apparatus that is used for reducing or increasing the voltage of an alternative current.
How do you calculate the of turn and the secondary voltage of the 15kw transformer?
First of all, transformers are rated in volt amperes, not watts. Secondly, in order to determine a transformer's turns-ration, you need to know its primary and secondary voltage ratings.
I am not certain what is being asked here. RMS is Root Mean Square which is basically the DC voltage which would produce the same amount of heat in a heating element as the AC voltage in question. Since AC is continuously changing in polarity and voltage, it is handy to use the RMS voltage rather than the peak (169.7V for 120V RMS) or peak-to-peak (339.4V for 120V RMS). The peak or peak-to-peak voltage is handy to know when considering the maximum values such as in rectification.
It's been said that a quarter inch length spark can be upwards of 20,000 Volts.
In a series circuit how the total resistance of several bulbs compare to the individual resistances?
The greatest resistance is two bulbs in series. The equivalent resistance is series is R1+R2 while in parallel the resistance is R1R2/(R1 +R2). R1 +R2 is greater than R1R2/(R1+R2); e.g. if R1=R2 = R the series resistance is 2R and the parallel resistance is R/2.
What is the scientific principle that makes a simple electric motor run?
In a permanent magnet motor, electricity is used to create an opposing magnetic field to the one existing due to the magnet. This creates a force that causes the motor to spin.
In a motor without a permanent magnet, electricity is used to create two opposing magnetic fields.
The total resistance of the circuit increases. hence the new resistance after adding the resistance will be
new resistance = old resistance + added Resistance
There is a small mistake in the question. The second word is 'changes' not 'charges'
How do you modify an automobile alternator from DC to AC?
The automobile alternator is already an AC device. It generates three phase delta AC, which is then rectified with a six diode full wave bridge array into DC.
You don't really want to modify it, though, as it is designed for the specific application. It is possible, though, to connect to the stator terminals and access three phase AC. You would then need to redesign the exciter (rotor) control circuit in order to manage the output.
If you are thinking about doing this as an alternative to a generator to supply your home during a power outage, don't; its not worth the effort - buy a generator.
Why is a power transformer so heavy?
Due to the heavy coils found inside the body also you will find an insulation that is oil type, that s why it s so heavy , but if u look at the dry type transformer u will find it so light and compact
that s all i know my sir
Eng: Amr
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The reason that power transformers are so heavy is from the steel laminations that the core of the transformer is built from. The outside transformer is constructed out of steel which also adds to the weight. Transformer coils these days are using aluminium wire for the primary and secondary wraps. This keeps the weight down and also helps in preventing copper theft.
What is the role of iron core in a transformer?
because the core must be magnetic in order to induce a current
A transformer's core is rarely made of iron. It is more usually manufactured from a silicon steel. Often, manufacturers make their own alloy and give them various trade names, such as 'stalloy'. Just like iron, silicon steel, is categorised as a 'soft' magnetic material, which means that it is easily magnetised and demagnetised, which is essential as it takes a great deal of energy to magnetise and demagnetise 'hard' materials. making them completely unsuitable for transformer cores.
