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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
What is the cable size for 3.7 kw 3 phase motor?
It depends on more than Wattage or horsepower. In your question, you also need to mention line Voltage, power factor, and whether single or three-phase. Cable size is based on current, so we need to know everything to calculate current.
Which parameters speed of DC shunt motor depend?
base speed is the speed with full voltage on the shunt
this speed is mostly from the number of poles , single pole fastest
max speed is when you weaken the shunt
the limit is the amount of power the armature can take
and thing like bearings an strength of the reinforcement of the windings
Can you use a rectifier as a inverter if you place your ac supply were there should be an ac output?
You probably mean "... where there should be a DC output ?",
and the answer is "No. They don't work in reverse.".
The NM represents the type of sheath on the cable. NM stands for Non Metallic sheath cable..
If voltage is 12 volts and ohms is 0.5 how many amps in circuit?
Ohm's law: Volts = Amps * Ohms, or Amps = Volts / Ohms 12 volts / 0.5 ohms = 24 amps
Why is class A winding insulation is only used in oil filled transformers?
This is because the oil has flash over point at 140 deg.Cl and the winding insulation cannot exceed the flash point of the oil.
Can I check the capacitor value by using analog or multimeter?
You can see if the capacitor charges and discharges with an ohmmeter. You can check the value of the capacitor if the multimeter has the facility. With an ESR meter you can establish the value of the capacitor while in circuit.
Why it is called alternating current and not alternating voltage?
Although in AC, the voltage does change, it is the reversing of direction of flow of the current which was used to designate the AC name.
AnswerIn engineering terminology, the abbreviation a.c. is considered to be an adjective. So, it is quite normal to talk about an 'a.c. voltage', in just the same way as we describe an 'a.c. system', or an 'a.c. motor', etc. However, it is also correct to use the term 'alterating voltage', where applicable.The plus and minus voltage sign for resistance voltage, drops for battery voltages, and drops for currents is determined by convention. You can use whatever method you want - so long as your use is consistent, your analytical results will be correct for you.
The commonly accepted convention, however, is best. This way, other people reviewing your results will not be confused unless, of course, they use an atypical convention.
Electric current flow is electron flow. The battery terminal marked "negative", or the cathode, is the source of electrons, and those electrons are drawn to, and flow towards, the "positive" terminal, or anode.
Consider a simple circuit, consisting of a battery in series with a resistor. Draw the battery on the left, with the anode up. Draw the resistor on the right. Connect the anode to the top of the resistor, and the cathode to the bottom of the circuit. (Actually, this is also a parallel circuit, with the battery in parallel with the resistor. It depends on how you see it, because this is a simple circuit.)
Current flows out of the bottom (cathode, negative) battery terminal, into the bottom of the resistor, up through the resistor to its top, over to the left, and into the top (anode, positive) battery terminal, and down through the battery, completing the circuit at the cathode. This is counter-clockwise, if you have drawn the circuit as stated.
If you place a voltmeter across the battery, you will see that the anode (top) is more positive than the cathode. If you place a voltmeter across the resistor, you will see that the top is more positive than the bottom. It does not matter if you measure across the battery or the resistor, the voltage will be the same. If you place the voltmeter across the wire on the bottom, or across the wire on the top, you will see that the voltage is zero.
With the preliminaries out of the way, now to the convention.
Current flow is counter-clockwise, from cathode to anode. If you were to draw a current arrow, you could draw it counter-clockwise, down through the battery and up through the resistor. You would label the first point that the current encounters (the bottom of the resistor) as negative, or minus. As the current goes through the resistor, it becomes more positive, so you would label the top of the resistor positive, or plus. Go over to the anode. That is also plus. The current is made more negative due to the battary being a source, rather than a load, so the cathode is minus.
These pluses and minuses are relative to each other, and they are also relative to some common reference point, said point by convention being the cathode. In this simple circuit, there is only one point that has any voltage different than the cathode, and that is the anode, so this distinction might be vague.
Consider then, the case where the resistor is actually two resistors in series. Again, the bottom resistor starts minus on its connection to the cathode, it becomes more positive as the current goes up, making the top of the bottom resistor plus. The bottom of the top resistor is minus, because current is flowing into it, and it becomes more positive as the current goes up, with the top of the top resistor plus.
When you measure voltage across an element, you see the voltage for that element. If, instead, you measure the voltage relative to the common reference point, and there is more than one element between the voltmeter's leads, you add up the voltage rises or drops to figure out what to expect. In fact, this is the basis for Kirchoff's voltage law - that the signed sum of the voltage drops around a series circuit always adds up to zero.
So, this preliminary convention is that current flow leaves the minus terminal of a voltage or current source, and enters the minus terminal of a voltage or current load. It then enters the plus terminal of a voltage or current source, and leaves the plus terminal of a voltage or current load.
Now, to confuse you, another convention states that current flows from plus to minus, not from minus to plus. This means that current leaves the plus terminal of a source, and enters the plus terminal of a load, and it enters the minus terminal of a source and leaves the minus terminal of a load.
It does not really matter which convention you use. The positions of the plus and minus signs will be the same - its just that the current arrow will point in the opposite direction - in this example, clockwise instead of counter-clockwise. What is important is to be consistent in your use of the plus or minus sign as the current enters and leaves a source or a load.
The convention of current flow is arbitrary. So long as you are consistent in your application, you will get the correct results.
It is generally accepted that current flow is electron flow, which means that current flows from the negative side of a voltage or current source towards the positive side.
Often, however, current is considered to flow from positive to negative. While this makes perception in circuit analysis more straightforward, it does not change the analytical results.
A Polarized capacitor means that the capacitor is polarity sensitive. if you were to connect the capacitor incorrectly the capacitor would blow up. A capacitor that is marked as being polarity sensitive will have the negative lead labeled usually with a white strip. These capacitors can only be used in conjunction with a dc source. Always consult a professional when installing electrical equipment.
What is the inductance of a circuit containing two 10 mh inductors connected in parallel?
Inductance in parallel is the reciprocal of the sum of the reciprocals of the individual inductance's.
LPARALLEL = 1 / SummationI=1toN (1 / LI)
What type of circuit in which voltage is constant?
A mercury battery will provide constant voltage. A voltage regulator circuit will also.
This question is not understandable. You can use a step up transformer to increase voltage; you can't increase voltage by producing electricity at a lower voltage; this will result in current flow into your generator, not current flow out (similar to operating a generator in the leading mode).
Please explain further under "discuss question".
You didn't mention whether the voltages are single phase or three phase or whether it is a commercial machine or one used in the home. I am assuming that you are asking about a single phase washer. That being said yes, 208 volts can be stepped up to 440 volts. To have the washer converted would mean finding a 440 single phase motor with the identical frame type that would fit the same configuration that the 208 volt single phase motor now resides in. The control voltage for the internal controls would also have to be changed out to the new voltage. The transformer would cost as much as a new machine so that is out of the question. You might want to price out a new 440 volt machine, sell the old 208 machine and the money that you get for the old machine, apply it to the cost of the new machine.
How are motor start capacitors rated?
Motor start capacitors are rated with two main values. One is capacitance in micro farads and the other is in voltage.
How many amp in 480 vac 3- phase primary transformer if the secondary it's 120 vac?
This 480-v three-phase transformer probably has a 208-v three-phase secondary which has 120 v from each line to neutral. In that case the primary current is 0.433 times as much as the secondary current, so 100 amps in the secondary means 43.3 amps in the primary.
Why the impedance of infinite bus bar is zero?
...because it is an infinite bus bar, meaning it can supply infinite current. By Ohm's law, since the voltage at the bus bar is fixed, to have infinite current, you must have a zero impedance.
Are diodes only used in a dc circuit?
There are lots of diodes - a "diode" is simply a device that has two electrical connections.If you refer specifically to the rectifying diode, it is used to convert AC current to DC current - so, it is used in a circuit that has BOTH AC and DC.
Explain the principle of a alternating current generator?
Well, a magnetic will be spun with one pole up and then the other pole up inducing a magnetic flux, and a coil of copper will be encompassing the magnetic and every time the magnet flips its poles around, thus inducing magnetic flux, a small bit of current will be made. When the flipping of the magnet is faster the current comes faster, but alternates with the flipping of the magnetic, or the changing of the magnetic flux.
because DC generator generates generally generate DC power but as it has slip rings which convert it into ac output power
An appliance cable or "flex" outlet is a type of electrical outlet which is NOT a "socket outlet" to take plugs for appliances so that they can be plugged and un-plugged.
An appliance cable or "flex" outlet has terminals inside it. The terminals allow the wires in an appliance cable or "flex" to be connected to the household wiring in a building.
The household wiring comes from the building's main electrical power panel, which carries the main circuit breakers. The circuit breakers are fitted to protect the household wiring from catching on fire if any circuit is overloaded.
Such appliance cable or "flex" outlets also have strain-relief clips. A strain-relief clip helps to prevent the cable from being yanked out of the outlet if the appliance gets moved away from the wall where the outlet is installed.
Such outlets, with terminals inside and strain-relief clips, are used for fixed appliances, such as ranges or dryers, which should never have to be un-plugged during normal use of the appliance by the user.
"2kw fire" if this refers to an electric fireplace then you also need to know the voltage that is used. 1Kw = 1000 watts. Watts = Amps x Volts. Amps = Watts/ Volts. Amps = 2000/Volts.
How do i charge 94 silverado ac?
Go buy a can of R-134a and the hose that has the quick release for the low side. Napa would have this. You hook this hose into the low side and hold the can upside down until the compressor starts because it now has enough freon to run. Check how cold the air is now. If it does not feel around 50 degrees then add more freon with the bottle facing up so as not to slug liquid into the compressor.
