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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
Why power is measured in terms of kva not in kw in ac supply?
Unlike DC in AC Power is the Product of Voltage*Current*Power Factor
P = V*I*PF
In the above expression power factor is a variable quantity which can be different for different circuit hance does not allow you to specify ratings in KW rather then KVA.
When are electromagnets used to increase or decrease the voltage of electric currents?
Electromagnets are never used to increase or decrease the voltage in a circuit. These magnets in conjunction with a rotating device (an armature) can create a voltage but the do not have any effect on a voltage.
What is MCC In electrical Field?
mcc stands for MOTOR CONTROL CENTRE.it is usually used for a/c units.
PSPICE is a circuit simulation program. Different groups may use this for their own reasons over other software solutions - good library of parts, tech support, ease if use, we've always used it, and the list goes on. Many schools may use because there is a free student version - a great alternative over forcing students to shell out 5k for a professional version.
What is the name of the transformer that the Corvette turns into in transformers 2?
I believe that the name is Sideswipe. When I was looking it up on different places it said "Corvette Stingray" but that's the name of the car
Yes, the Chevy Corvette Stingray Concept was Sideswipe. :) -K
1st make sure the power is turned off
Disconnect one lead on primary side of transformer and using an ohm meter check for continuity. You will probably get a low ohm reading if you get no reading the windings are broken and transformer is no good
2nd test using ohm meter again check for winding to ground you should get no reading. If you get a ohm value the transformer is shorted to ground
Repeat these tests on secondary side
With power on and fuse removed with a voltage meter check for power on secondary side
If it is okay turn off power and install fuse
If fuse blows again check for shorts in circuit
Remember to be careful when power is turned on
What affects the resistance of a cunductor?
The resistance of a material depends on:-
- The material itself.
- Length of the conductor.
- Area of cross section of the conductor.
- Temperature.
There are a number of advantages for using PLC(Programmable Logic Controller) control compared to other conventional types of control.
Here are a few examples:
- With a large control scheme, a PLC takes up less room.
- You can change your control scheme (program) without having to physically change the wiring to a number of relays.
- A PLC is relatively much faster and allows for closer process tolerances.
- A PLC is more reliable as there are no moving parts.
Why there is a maximum cable length allowed for CSMA CD?
The CD in CSMA/CD stands for "collision detection." Since multiple devices (potentially) share the same network (the MA or "multiple access" portion of the name) when they are sending data, there must be a way to tell if two devices are trying to send at the same time (a "collision"). The way that a typical CSMA/CD protocol such as Ethernet does this is by having each device "listen" during its own transmission. If it "hears" another device starting to send while it is already sending, it stops and tries again after some delay.
Part of this is defining a minimum packet length that is long enough that, for a given length of wire, any given sender can be sure that the beginning message got all the way to the other sender before it assumes there was no collision and that it succeeded in sending the packet. Even at nearly the speed of light, it takes some time for that signal to go down the wire.
With 10 Base-T Ethernet (10 million bits/second), the 64 byte minimum would take long enough that the signal could get a kilometer down the line before the first sender was done. With 100 Base-TX, the same minimum only gets 1/10 the distance (100m) because the bits are being sent out ten times faster. With gigabit Ethernet, they actually had to increase the minimum packet length just to make sure that the cable length could stay at 100m.
One 100-watt bulb draws 0.87 amperes of current how many amperes will 17 such bulb draw?
If this is a homework assignment, please consider trying to answer it yourself first, otherwise the value of the reinforcement of the lesson offered by the assignment will be lost on you.
If a 100-watt bulb draws 0.87 amperes of current, 17 of them will draw about 14.8 amperes, (0.87 times 17), if they were wired in parallel.
However, wiring them in series would not give you 0.051 amperes, (0.87 divided by 17), as one might expect, because the resistance-temperature coefficient of bulbs is quite dramatic, so more current would actually be drawn because the bulbs would be much cooler. How much more would require testing. You could do this by supplying 6.8 volts to one bulb and seeing what you get, or just hook 17 of them up in series to 115V.
What kind of motor can you use to make a homemade wind generator?
For demonstration purposes you could use an ordinary small DC motor - like the kind used in a model railway engine, a toy motor car or model boat - driven by a light plastic propellor. Connect the motor to a flashlight bulb of about the same voltage as the motor.
You must be sure there is enough wind to drive the propellor and, to get the bulb to light up, you may have to try several different experimental set-ups. You will probably have to try using several different sizes of propellor along with various sizes of small flashlight bulb.
Another set of opinions
Wind is the Primary source for Generting power In case of Wind Energy System. Its a fact that Wind energy is not constant but variable, So We cannot Use conventional Synchronous Generator For power generation.Instead We Have to Use a variable Speed Prime mover. for eg. A Wind Turbine. It depends on Wind Velocity and uses the Kinectic Energy of wind for rotation. Since the Prime mover is running at Variable speed we need to connect a Asynchronous Generator to it which is an Induction Generator. All things I Said above are basics, i mean the Old technology. Today its almost outdated because as the It is Asynchronous Generation we cannot connect to our conventional Grid System, instead we Have to use it as a isolated power System. But Thanks to the modern Technology which is Pitch Control Techinque, ie, The blade angle of Prime mover Changes w.r.t wind nd Speed of turbine is maintained constant irespective of wind Velocity. Therefore now a day we can use Synchronous Generator In Wind power System.
Then going to the question asked, a ordinary Toy Car motor which Is DC that Runs on battery can be used For make An model of wind Power System For An exhibition purpose. In Real System the Prime Mover is wind Turbine not Motor that Runs the Generator.
What happens to electricity pylons in the summer?
Usually in summers due to high temperatures conductors became lengthy due to it pylon has to sustain more pressure of conductor weight and hot windy conditions thus there will be more vibration and humming sound in pylon can be visible.
How many deep cycle batteries would you need to run an corded electric lawn mower for about 2 hours?
Not enough info, but divide the Amp/hr rating of the battery by the amperage draw of the machine to get ad approxiamation
What is the function of SIM card in telephone?
The function of a SIM card is relatively simple. It's not a super advanced item that controls your phone, rather, it is basically nothing more than a storage device for information useable by yourself and your cellular carrier. It has limited memory to save this information. And this 'storage device' is also the reason you can use someone elses phone, put your SIM card into it and have all of your phone numbers and information about your account on their phone. This is of course unless their cellular provider has SIM-locked their phones. Anyways, long story short
SIM-Card = storage device.
P = IV
I = V / R
I = 14 / (9 * 4) = 14 / 36
IV = (14 / 36) * 14
IV = 5.444 Joules
How do you connect a diode across a 24 volt valve?
Use of a diode across a DC electromagnetic device, such as a valve, is to counter the reverse voltage (EMF) caused by the collapse of the magnetic field when the power is turned off. If the diode were not present, the reverse voltage can become very large, even to thousands of volts or more, and it can damage the associated circuitry.
In this application, the anode is connected to the negative side, and the cathode is connected to the positive side. When power is applied, the diode does not conduct. When power is removed, and the inductor attempts to maintain the current flow by generating a reverse voltage, the diode conducts until the magnetic field collapses.
voltage, current, resistance, horsepower, contacts, overloads, coil, terminations, NEMA, IEC, NFPA 70 NEC, motor controls, NFPA70E . . .
A contactor is a double make/break per phase switch that opens and closes the circuit to the motor by energizing a coil (electro-magnet) using a motor control circuit (usually, but not always a lower voltage than the motor circuit). The motor control circuit goes through a normally closed set of contacts that will open if the overloads that are in series with the motor circuit sense too much current going to the motor.
A guard ring is a circular conductor located near the bottom of a high-voltage insulator string, from where the line conductor or conductors are suspended. It's function is to evenly-distribute the potential gradient across the length of the insulator string, by preventing the concentration of electric field in the vicinity of the line conductor, which would otherwise act to break down the insulating properties of the insulator chain.
If the voltage is 500 volts, and the power is 200 kilo-watts, then the current is 400 amperes. (Watts equals Volts time Amperes)
The resistance of the conductor has nothing to do with this calculation, but that fact that the conductors are 0.1 ohms means that the voltage drop across each conductor is 40 volts. (Volts equals Amperes times Ohms) Since there are two conductors, the total voltage drop is 80 volts, and the voltage available to the load will be 420 volts.
What kind of wound mechine is this...if it is wave wound mechine than Eg:357
What is the equivalent of 200watts in amperes?
You need to know the voltage also, then it's a simple bit of maths: Watts = Volts x Amps.
The reason for the total voltage drops across the capacitance and inductance IN AN AC CIRCUIT has to do with the different phase angles of the voltages.
First, current is the same value and same phase angle everywhere in a series circuit. But, voltage across a capacitor lags current by 90 degrees (capacitor current leads voltage). Next, voltage across a pure inductance leads current by 90 degrees (inductor current lags voltage).
The rule that all voltages in a series circuit have to add to the supply voltage still applies, but in this case, the voltage drops are added VECTORALLY, not arithmetically. If you were to graph this addition, you would show any resistance voltage in phase with the current, the capacitor voltage at -90 degrees to the current and the inductor voltage at +90 degrees to the current, for a phase difference between them of 180 degrees, cancelling each other out.
In a series resonant circuit, the impedances of the capacitor and inductor cancel each other. The only impedance to the flow of current is any resistance in the circuit. Since real-life inductors always have some resistance, at least there is always some resistance in a series resonant circuit.
Can compressor run in DC volt?
There are compressors with motors designed to run on DC. A compressor with an AC motor can't.
