0
Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
When secondary coil is open there is no current in the primary coil WHY?
I am assuming the question is about the power / distribution transformer and not the current transformer.
The primary current is a function of load connected on secondary. With the open secondary, there is no load, no current, it is open circuit. Hence no primary current.
However there is always some small amount of no load current in the primary winding.
For USA, Canada and other countries running a 60 Hz supply service.
If you had to ask this question here you need to learn more about your local wiring code re all the items you must use for a new household AC power range circuit.
Serious home fires can result from incorrectly installed new circuits.
So that the new installation is safe and legal - and complies with the terms of your home insurance policy - you must use the correct type and size of cable, the correct type of circuit breaker and the correct type of wall outlet.
From the local wiring code, a licensed electrician will know which size of wire to use because the answer depends both on the current to be carried (amps) and on the length of the run from the breakers on the main supply panel to the place where the outlet for the kitchen range is to be fixed.
Another answer
#8 awg Copper or #6 awg Aluminum but first of all you should check in the NEC wire sizing tables for the cable size given for your length of run. If installing in conduit install no more than 6 current carrying conductors, i.e. black, red, or white, or you must increase the size of your wire. If installing this circuit using a jacketed cable like NM-B then you should use a 4 conductor cable, not 3 conductor as in the old days.
<><><>
As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.
Before you do any work yourself,
on electrical circuits, equipment or appliances,
always use a test meter to ensure the circuit is, in fact, de-energized.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
What is the difference between armoured unarmoured and flexible cables?
Armored electrical cable contains insulated electrical service wires protected by a flexible steel covering. Unarmored electrical cable has no protective flexible steel covering, its covering is made of plastic.
What voltage you get at home in India?
The single phase voltage in India is 230v when we check with the phase and the nutral single line
What is three phase transformer?
A polyphase system is a means of transmitting ac power and it has N live wires with the currents phased by 360/N degrees between them. This arrangement when N is 3 or more needs no neutral wire because the return current for each one of the N wires flows back along all the other live wires.
The world-wide standard for electric power transmission uses N=3 and is called 3-phase. Power transmission needs 3 wires when the the three currents are balanced (equal) and 4 wires in other cases where the load currents might not be equal, in which case current flows in the neutral fourth wire.
Those Plasma Balls are really fascinating. There is a high voltage source
attached to the inner ball that causes a current to flow to the nearest point
with a lower voltage. The ball is filled with a gas that glows when it has
electricity flowing through it. When nothing is touching the ball, the current
just flows anywhere onto the ball. When you touch the ball, some of the current
can flow through the glass and into you. Because your body is providing a place
for the current to flow, the electricity keeps flowing and the lines of current
can stay connected to the point on the ball that you are touching.
What is the fuel consumption of a 30 KVA Perkins generator at full load?
The Perkins 100 KVA generator uses approximately 23.8 Liters per hour. The Perkins KVA generator can be purchased at any Perkins licensed dealer.
How do you calculate total resistance in parallel?
In words: The total conductance is the sum of the individual conductances. Since conductance is the reciprocal of resistance:
1/R = 1/R1 + 1/R2 + 1/R3...
where R is the combined (or equivalent) resistance, and R1, etc. are the individual resistances. In other words, you first take the reciprocal of the resistances, add everything up, then (to get the actual combined resistance), you take the reciprocal again.
Sample calculation: resistances are 2 and 3 Ohms.
1/R = 1/2 + 1/3
1/R = 3/6 + 2/6
1/R = 5/6
R = 6/5 or 1.2
How does the Kelvin bridge differ from the wheatstone bridge?
kelvin's bridge is the modified version of wheatstone bridge and used to measure resistance values less than 1 ohm.
What three values in an electrical circuit are connected by Ohms law?
Ohm's Law simply states that, under certain circumstances, the current (I) passing through a circuit is directly-proportional to the potential difference (U) applied across that circuit.
So, strictly speaking, Ohm's Law, relates just twoquantities: current (expressed in amperes) and potential difference (expressed in volts).
The ratio of potential difference to current is, of course, resistance (R). So, by extension, Ohm's Law can be written as R = U/I. But, strictly speaking, resistance is not mentioned in Ohm's Law.
However, it must be realised that Ohm's Law is NOT a universal law; in other words, it does not apply in all circumstances. In fact, it does not apply to a great many electronic devices, such as diodes, etc. In fact, it only applies to pure metal conductors provided their temperature remains constant for variations in voltage.
Why the voltage between phase to neutral is 240v compared to phase to phase is 415v?
What you are describing is a three-phase, four-wire, system having a phase voltage of 240 V and corresponding line voltage of 415 V.
You do not add the three phase voltages (3 x 240 = 720 V) to obtain a line voltage.
The three phase voltages are actually displaced from each other by 120 electrical degrees, so any pair of phase voltages must be vectorially-added to obtain a line voltage. If you perform this calculation, you will find that the line voltage is always 1.732 times larger than the phase voltage. So, 1.732 x 240 = 415 V.
What is meant by the term short circuit?
When a wire is cut in a circuit, a gap is made and the current can no longer circulate, known as an open circuit.
When 2 parts of a circuit touch, that shouldn't, for example - a wire comes loose and comes into contact with another part of the circuit, its shortening the route of the current in the circuit. So its a short circuit. When this happens 99.9% of the time the result will be a spike in amp's, so tripping any circuit protection, MCB's, fuses.
A good example of a common short circuit is faulty windings on a 3-phase electric motor. If the resin separating the windings becomes damaged it can cause 2 or even 3 of the motors phases to come into contact causing the motors overload protection to trip.
What is the standard electricity service voltage used in India?
In most parts of the world this is 50 Hz, although in the Americas it is typically 60 Hz. Current usage by country or region is given in the list of mains power around the world at: http://en.wikipedia.org/wiki/Utility_frequency
Why dc can be stored ac cannot stored?
Why direct current (DC) can be stored but alternating current(AC) can not be?
Current means flow of charge per unit second.
Any flow cannot be made stationary. Then it is not flow.
Hence both direct current and alternating current cannot be stored.
We can store only charges.
In capacitors we store charges and not current.
For storing we use direct supply or direct voltage
When a capacitor is connected to a battery, which is a source of direct voltage, each plate of the condenser get charged. Charges remain in the plates. No current flows in between the plates.
When the source is removed, there are some charges left in the plates.
We say that charges are stored in the plates.
If an alternating source of supply is connected in between the plates,every instant ,the charges in the plates are alternating and they are not stationary.
When ac supply is removed, all the charges move out of the plates and hence no charge is left in them.
Hence charges can be stored with dc supply and not with ac supply.
However as long as the ac is connected to the capacitor, the capacitor gets stored and emptied with the frequency of the ac supply.
What happens to electric current as voltage gets large?
If the resistance of the load is kept more-or-less constant, then the current also becomes larger. On the other hand, if the power of the load is kept more-or-less constant, then the current becomes smaller.
What types of material can a winding machine be used on?
A winding machine is used to wind the string, wire, cable, thread, rope, etc onto a spool or bobbin. They are of various types from simple winding machines to complex programmable winding machines like CNC winding machines. Mostly winding machines are used in textile, and paper industries, to quickly wrap a large amount of string or paper onto a spool. These winding machines are used by small to large businesses according to the winding needs.
How many 75K resistors must be put in parallel to provide a total resistance of 15K?
5000
For Parallel resistors:
Rtotal = R / N
Rtotal is total resistance
R = Value of resistors
N = number of resistors
15 = 75000 / N
N = 5000
Can you convert a 9v battery snap to a dc power supply?
You would need a 9V dc supply. The potential current output of you supply myst be greater than or equal to the current draw of the pedal. (100ma load on a 150ma supply: fine. 150ma load on a 100ma supply: bad.) With these conditions met you can just get another 9V snap and wire it to your supply. Remember, as you are connecting two snaps together, the polarity of the snap for your supply will be reversed. (Red is - and black is +) CHECK YOUR WORK! If you mix up the polarity, you could smoke your pedal. You can also make your own regulator with a LM317 voltage regulator from a higher supply. This will only work with another low voltage DC supply with a voltage output higher than 9V. It will not boost the voltage and will not work with line voltages. It is a common IC and many manufacturers make them. Check your pedal. Most of them have DC in jacks so you don't need to hook to the battery clip.
Watts is the product of amps and volts. It's amps times volts. The watt (W) is a measure of power (P). It's the SI unit of power, actually, and it's a joule per second. The volt is a measure of electrical potential difference, and is the SI (derived) unit of electromotive force, or EMF (E). Voltage, which is measured in volts (V), is the force that drives electron current flow (I), which is measured in amps (A). In relationship to the volt, the watt is current flow times voltage, or, said another way, a watt is amps times volts. As regards watts and volts, they are "linked" by current. Let's look at the expressions: Power = Current x Electromotive force => P = I x E Power (in watts) = Current (in amps) x Electromotive force (in volts)
Voltage is a measure of electric potential, in joules per coulomb. Watts is a measure of energy transfer rate, in joules per second.
To complete the answer, amperes is a measure of charge transfer rate, in coulombs per second, which is why voltage (joules per coulomb) time amperes (coulombs per second) is watts (joules per second).
Classification of Continuous Time signals and Discrete time signals?
we often confuse our-self with continuous time and analog signals.
An analog signal is a signal which can take any amplitude in continuous
range that is signal amplitude can take infinite values on the other hand
a digital signal is one whose amplitude can take only finite numbers of values
THE TERM CONTINUOUS SIGNAL AND DISCRETE SIGNAL CLASSIFY THE SIGNALS
ALONG THE TIME (i.e. horizontal axis) where as THE TERM ANALOG AND DIGITAL
SIGNAL CLASSIFY THE SIGNAL ALONG THE AMPLITUDE (i.e vertical axis)
