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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

How do you calculate earth leakage current for certain load example 5KW motor 660Vac?

There are many factors that determine what the leakage current will be. You could find out what the insulation winding resistance of the new motor should be and use the 660 volts and Ohm's law to calculate the current. If you measure this using a DC insulation tester however it probably will not yield an exact measurement since the test is not under normal operating conditions, but is a DC voltage test. To get the best measurement you really need to test the motor under operation and use a leakage clamp on the ground connection to see what the current really is since other factors come into play such as the insulation resistance, imbalance and frequency. An example of a tool would be the Fluke 1630 or Fluke 360.

In a wet type of voltaic cell what is electrolyte?

In a wet type of voltaic cell, the electrolyte is a liquid or gel substance that allows the flow of ions between the two half-cells to maintain charge neutrality. It helps facilitate the flow of electrons in the external circuit, allowing the cell to generate electricity. Examples of electrolytes in wet cells include acidic or alkaline solutions like sulfuric acid or potassium hydroxide.

Why relay contact haS two different ratings for AC VOLTAGE and DC VOLTAGE?

AnswerRelays rated for AC/DC use: the DC rating being lower than the AC, This is because DC can establish an arc across the contacts which cause the contacts to burn more,so they are rated lower.When I use relays on DC I will use double pole relays an put the contacts in series this gives a wider gap when the relay opens and helps exstinguish the arc quicker.Hope this helps.

AC IS +/- WHILE DC IS JUST A LEVEL AC120 MUST WITHSTAND THE PEAK VOLTAGE

Reply: How is putting the two sets contacts in series going to help?The same potential is still being broken at the first set of contacts.>-------------0___0--------0___0---------->Parallel would make more sense to me, since then the current would be split between the two sets of contacts.

What is working principle of Auto blood analyser?

Auto blood analyzers work by using specific reagents to analyze the different components of blood, such as red blood cells, white blood cells, platelets, and various biochemical markers. These machines automate the process of sample preparation, analysis, and data reporting, allowing for faster and more accurate results compared to manual methods. The analyzers rely on various techniques like spectrophotometry, impedance, and flow cytometry to detect and quantify blood parameters.

What is the difference between earth and neutral?

For USA, Canada and countries running a 60 Hertz supply service.The ground or "earth" wire is a circuit's safety protective wire that normally carries no current.

It is there to force a fuse to blow or a circuit breaker or GFCI to trip if a fault condition occurs in any appliances, their flexible cords or plugs that are connected into the circuit.

By carrying away the excess current in a fault condition - which should cause the protecting fuse to blow or circuit breaker to trip - the "ground" or "earth" wire protects the building and its occupants because the power should be cut off before anyone gets electrocuted or any overloaded circuit wiring or appliances catch on fire.

The neutral is the normal "return" wire: in systems where the load is supplied from only one hot (or "live") wire, the neutral completes the circuit and carries current back from the load to the power station.

All the neutral and ground (or "earth") wires in a building are tied or linked together at the incoming service main breaker panel. This is the only place they should ever be tied togetherbecause it is "upstream" of all the fuses and/or circuit breakers protecting the hot (or "live") wires for the various circuits installed in the building.

Warning: we must never assume that a neutral is safe to touch: it has to be checked with a voltmeter or a voltage indicator to be sure it is not "live". This is because a neutral wire is designed to carry current under normal circumstances.

So, if a neutral wire going back to the incoming main breaker panel has not been properly connected - or suffers a deliberate disconnection or some accidental damage which causes it to break - then it and any neutral wires connected to it further downstream will go live up to the break because of being connected to the downstream loads which still have hot feeds coming into them!

That is why we should never use a neutral as a substitute for a proper, separate, ground or "earth" wire.

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If some external accidental damage or electrical breakdown of the wiring's insulation occurred anywhere to the house wiring, to a socket outlet or to an appliance, these things could be very dangerous if there was no such protective wire.

For example, if there was no protective ground or earth wire, a fault could happen that is of a kind which did NOT draw enough extra current to blow a fuse or make the main circuit breakers on the incoming supply panel "trip" to cut the current off - but the wiring could still catch on fire and/or someone could be electrocuted!

Neutral wires are the return paths to the power generation station for current it supplies to the house or building via single live or "hot" wires in the branch circuits.

For more information please click on the Related Questions below.

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Earth (also called protective ground or ground) and Neutral are normally both near 0 volts to ground potential. The neutral service wire is designed to carry current and the "ground" or "earth" wire is designed so that it should carry no current unless there is a fault.

In North American 120 volt single-phase services, earth and neutral are connected together at each service entry and connected to the earth by a stake in the ground or other reliable grounding means. They are not connected at any other point inside the building. The neutral wire ends at the transformer near the building and does not connect back - via the distribution lines - to the power utility company's generating station(s).

In North American Electrical Engineering and code, the terms "neutral" and "ground" are not officially used. The formal term for neutral is the "grounded" conductor and the term for the earth or ground connection is the "grounding" conductor. Since these are easily confused, it is more common to use the terms neutral and ground.

In North America a 240/120 volt so-called "split single-phase service" from a center-tapped 240/120 volt utility service transformer is often used for major home appliances - such as ovens, ranges, water heaters, clothes washing machines and driers, air conditioning units, etc. - which take a high power draw.

They work as follows: the main heaters and/or motors run on 240 volts single-phase delivered from two "hot" wires. (Usually one hot is colored red and the other hot is colored black.)

If they include some low-power devices - such as time clocks, wash-cycle programmers, etc. - that only need 120 volts, the current for them is delivered from one of the above-mentioned red or black "hot" wires. A separate wire called a "neutral", which is normally colored white, is used to send the current from those small 120 volt devices back to the center-tap on the 240/120 volt service transformer.

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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.

How does the load affect voltage output of a series generator?

In a series generator, the voltage output is directly affected by the load. As the load increases, the voltage output decreases due to increased voltage drops across the internal resistance of the generator. Conversely, reducing the load will result in an increase in the voltage output.

How can a silica gel pouch get busted in a container?

The plastic in which the silica gel is sealed is usually very tough. (That's why it was chosen.) It's also "stretchy" enough to withstand a good bit of compression without failing. (You could stand on half of a pouch and it wouldn't rupture.) The most probable method of failure of the pouch is that it was cut or punctured in some way.

Can a Cellphone Speaker emit a High Frequency Tone which can kill whoever answers it?

No, a cellphone speaker cannot emit a high frequency tone powerful enough to kill a person. High frequency tones emitted by cellphones are limited in power and intensity and are not harmful to humans.

What color is A phase on a three phase busway?

A phase in a three-phase busway is typically identified by the color red. This color coding helps to easily distinguish between the different phases and prevent errors during installation and maintenance.

Can you use a light timer that is rated at 15A and 115V with a circuit that is rated at 20A and 120V?

Yes you can. Please be aware you have the situation of pulling more amps, in this case 5 amps, over the timmer before the fuse blows. which may damage the timer To avopid this appliances plugged into the timer should be rated at 15 amps or less. Thgere are different type circuit breaker immediate and time delay for where an appliance such as motors exceed the limit to start then drop down when running?

What is the time to complete one cycle of 60 Hz AC?

Hz is short for Hertz, which is the international standard (SI) unit of frequency of an alternating current (AC) voltage. 50Hz means the voltage alternates 50 times per second, 60Hz obviously means 60 times/sec. 60Hz is the normal frequency of the incoming power lines in North America, while 50Hz is seen in many European countries. While convertors exist to use electric devices on a different voltage, convertors generally are not available to use 50Hz devices on a 60Hz power grid, or vice-versa. While some devices can be used on either, many others will not work or may even be damaged. Check with the manufacturer to be sure. Incidentally, since the unit of Hertz is named after the German physicist Heinrich Hertz, it is customary to capitalize the H. So 60Hz is considered correct, while 60hz is not.

Why does your inside 4 outlet circuit randomly go off under no load only to come on again at random without tripping the breaker while outside lights on the same circuit stay on?

When your house was wired the outlets were probably wired using the stab in terminals on the back of the outlets, these tend to cause trouble over time.Turn off the power and rewire the outlets using the binding screw terminals.By chance if the outlets are wired on the binding screws, inspect all for loose joints.You may have to inspect every box and outlet on this circuit to find the problem. I once had a customer who was having a similar problem and it only showed up while playing the stereo very loud.We determined that the vibration was causing the stab in terminals to loose contact,we removed every outlet and switch and reconnected all by using the binding screws and the problem went away.Hope this helps.

Why is my 390 ford motor not starting and back firing?

Backfiring and difficulty starting on a 390 Ford motor could be due to issues with the ignition system, such as faulty spark plugs, distributor cap, or ignition timing. It could also be caused by fuel-related problems, such as a clogged fuel filter or carburetor issues. It's recommended to check these components to diagnose and repair the problem.

What is an electric shared neutral?

An electric shared neutral is the white or negative wire that is shared between two electrical circuits on a basic single phase system. Most electrical devices use 120 volts and require a "hot" wire and a neutral wire to operate. Some larger devices use 240 volts and require two "hot" wires to operate. Two circuit breakers in an electrical panel can share one neutral wire as long as the breakers are not on the same "leg" of power. When looking at an electrical panel there are usually two "legs" of power feeding all the breakers, each leg has 120 Volts to ground, if the "legs" are combined you will have 240 Volts. A neutral wire can be shared by two circuits as long as the breakers are on separate "legs". If someone needed to add two circuits in their home, the could run what is called a 3-wire romex, It has a black wire, a red wire, a white wire and a ground wire. The white wire is the neutral for both the black and red 120 volt circuits, and the breakers for the new circuits would need to be on separate "legs" in the panel.

How can voltage increase to 240V when only 120V is coming from the breaker box?

This could occur if the 120V supply is split-phase, where two 120V lines are 180 degrees out of phase with each other. When measuring from one of these lines to the other, you would see 240V. This is a common setup in residential electrical systems in the United States.

If an AC reverses direction 60 Hz then why are there different-sized receptacle slots for hot and neutral since v and i are alternating direction each half cycle?

It has been stated that: "AC outlets have polarity specific outlets because some devices can be ruined if the device is plugged in backwards." Although this might be true in some sense, the most important reason is enhanced user safety. This is a very good question; one that deserves a good answer. It is true that most household "alternating current" devices may work with a reversible (two-prong) plug inserted either way. It simply doesn't matter which way the current is going at any given moment. Many devices still have two identical prongs. The "polarized" plug is for extra user safety (and a three-prong plug is even safer, see below). Two-prong devices may be eventually phased out of production in many countries. AC outlets have polarity-specific sockets because some devices can easily become dangerous if the polarized device is plugged in backwards. This happens when the switch or fuse inside the appliance is designed to disconnect only the "hot" and not the "neutral" wire when the device is switched off because it is cheaper than switches that disconnect both wires. The "neutral" wire is typically connected to ground at the main panel, so it is safer to use the switch to open the "hot" wire. Also, in lamps (and light fixtures), the neutral should be connected to the lamp shell for added safety, and this could also become dangerous if reversed; the socket shell could still be "hot" even when the switch is off (and the light is out). Without a polarized plug, you can't tell which wire the switch will disconnect and may receive a shocking surprise! In theory, safe devices are designed to keep a user from touching either the hot or the neutral. In practice, if designers know which wires will be "hot" inside the device, they can take extra precautions to make sure they cannot break apart and electrify anything a user can touch. A broken "hot" wire can electrocute a user if he/she touches the metal enclosure and the user "completes" the circuit to ground. Therefore, many appliances now have a polarized plug so the switch always disconnects the "hot" circuit and extra attention is placed on safe disconnection and insulation of that conductor throughout the device. A so-called "double-insulated" (IEC Class II) device may have a non-polarized plug because the same safe design has been made for BOTH conductors, regardless of which one may be "hot", and without relying upon a third prong for safety ground of the enclosure. No single internal fault would be likely to cause an electrocution hazard. Furthermore, even with a polarized plug, a single internal fault can be deadly in an ordinary appliance. The third prong (ground) can save your life if there is an internal fault of the hot touching exposed metal, and a GFCI can save your life if there is an internal fault of the neutral to exposed metal (where you could otherwise become the missing "neutral" connection to ground as you are electrocuted).

What is double throw?

The term double-throw means that the operator can place or "throw" the switch into two different positions. One position feeds power from the utility system to the load. The other position feeds power from the standby generator to the load. Such a switch will prevent electricity, generated by the standby unit, to flow simultaneously to both the customer's home or farmstead, and to the utility's system.

Which voltage under-cabinet lighting of the 25 inch puck-type style would produce more heat 12 volt - low voltage - or 120 volt - if both bulbs are rated at 20 watts?

Let's retool this one. Watts is volts times amps. Check. Amps produce heat and not the volts. Now hold on just a minute there, partner. Heat is power. Power is watts. It's volts times amps. Power = Watts = Heat. So "amps produce heat and not the volts" is misleading. Amps and volts together produce heat, produce watts, produce power. It's true that more amps through a given resistance produces more heat than less amps through that same resistance. But it doesn't apply here. The lamps operate on different voltages and draw different amounts of current (and have different resistances). But they both deliver the same power.

The answer is right in front of us. Both lamps are rated at 20 watts. Both produce 20 watts of heat. Assuming similar incandescent lamp types, both will have the same brightness, and both will generate the same amount of heat. No math required.

Can you hook up two lines that are rated for 50 amps to a 100 amp breaker together or can you run a 50 amp line to a 100 amp breaker for an electric range?

Hire an electrician. While unintentional, the clearest statement of your question is that you don't know what you are doing. You want your over-current protection device to be the weakest link in your system, so it pops before anything is damaged. You're talking about hooking a 50A line up to a 100A breaker, making the wiring the weakest link. That is a good recipie for a house fire.

If you are rewiring an old farm and there are several circuits running 240V on a 12-2 or 10-2 wire using the ground as a neutral for what applications is this ok?

You might want to look a little closer at this. Because you said it was a farm, I have the suspicion you're looking at 220v motor circuits. 220v motor circuits, like 220v water heater circuits, do NOT have neutrals. Both sides of the line are hot, and the bare wire is ground like it's supposed to be. This is completely legal, and there's even a plug for it: the NEMA 6 series. (NEMA 6-20 for 20a service, NEMA 6-50 for 50a service and so on.) My favorite part of Leviton's 6 series receptacles is the marking on the box: "Industrial grade." You ever hear of a residential-grade metal lathe? All you can run off this are things that use 220v, and not 110/220 things like dryers and ranges. You could wire a water heater, something with a single-phase 220v motor, or a welder this way. If you need 110v in the barn, you're going to have to move around a bunch of stuff in the box to get the grounds onto a ground bar, or you'll need a separate panel for 110v. If you asked this question because you have no experience of working on the latest household power circuits and you hope to get enough information on this site to be able to do the job properly and safely, it is best to warn you not to rely on getting accurate information from this site about such a potentially dangerous subject.

By asking this question you probably aren't quite ready to take on this particular task.

Really, don't do this one yourself. Electricity is far too dangerous to handle if you have not been trained how to do this work. That you asked this question here shows that you don't already know your local Wiring Codes or Regulations so don't know how to choose the correct wire sizes and types to use for the lengths of run from circuit breakers to power outlets.

How to do this job depends entirely on the Wiring Codes or Regulations for the locality (Town/State) and on the exact location of the appliances you wish to hook up. If they are situated anywhere that is subject to water splashes or spray - such as in any room supplied with running water pipes, like a kitchen, bathroom, shower room, etc., or in a pool-side area - in many places nowadays it is actually illegal to attempt to do this kind of work unless you are already a licensed electrician.

For your safety and that of anyone else who may to use the appliance, ask a professional licensed electrician to advise you or to do the work for you.

As far as I know there is NO applications where a ground is used for anything but a ground.

There is a huge section of the NEC (National Electrical Code) that covers all the rules that cover the "ground" and I can't find any that allow it to be used as a "neutral".

Don't scrimp on the cost of wire, you don't want a burned down barn and a insurance company that won't cover it because you didn't follow the rules.

The plain answer is that you can't! There is no application where you are allowed to use the ground wire in non-metallic sheathed cable as a neutral! The neutral [an identified conductor] MUST BE INSULATED!

(LIFE SAFETY WARNING! [disclaimer] Electricity is dangerous! You can be injured or killed! Improper installations can cause fire, injury and death! Should you be doing this yourself?) This is one of those questions - if you know this little, you shouldn't be doing what you are planning...

No disrespect intended, but this is SO basic that it suggests you have not studied the subject at all! There are many good reference books and course books to study from.

IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS.

If you do this work yourself, always turn off the power

at the breaker box/fuse panel BEFORE you attempt to do any work AND

always use an electrician's test meter having metal-tipped probes

(not a simple proximity voltage indicator)

to insure the circuit is, in fact, de-energized.

Where is the Circuit breaker located on 2000 Ford Windstar and how do you test it to see if it needs replacing?

The circuit breaker on a 2000 Ford Windstar is typically located in the fuse box under the hood or in the interior fuse panel. To test it, you can use a multimeter to check for continuity across the terminals. If there is no continuity or if the circuit breaker appears damaged, it may need to be replaced.

Kvar is equal to what?

kVA is the unit for apparent power. Apparent power consists of active and reactive power. Active power is the share of the apparent power which transmits energy from the source (generator) to the user. Reactive power is the share of the apparent power which represents a useless oscillation of energy from the source to the user and back again. It occurs when on account of some »inertia« in the system there is a phase shift between voltage and current. This means that the current does not change polarity synchronous with the voltage. But the heat generated in a winding as well as the eddy current losses generated in a transformer core depend on the current only, regardless of whether it aligns with the voltage or not. Therefore the heat is always proportional to the square of the current amplitude, irrespective of the phase angle (the shift between voltage and current). So a transformer has to be rated (and selected) by apparent power. We define "complex power" as voltage times current (V*I), and thus the unit for power is the Volt-Amp (VA). When a circuit contains non-resistive elements (such as transformers), there is a component of power called "reactive power", which is power that is transmitted as a result of energy stored in inductors and capacitors. Reactive power does no useful work. Complex power is the sum of reactive power and real power (power which does work). When only real power is considered, the unit of power is the Watt. Transformers are rated in VA and not W because heat generated by electricity flowing through a conductor is proportional to the current flowing through the conductor. Although reactive power does no work, the current exists nonetheless and must be accounted for when selecting the proper sized wiring.

How is it that devices which use 2 leads to make 240V don't need a return wire and where does the electricity go and how?

240 Volts uses both phases of the incoming service (each at 120 Volts and 180 degrees out of phase). Since the load is "balanced" there is no need for a separate "return" (when one phase is off the other is on). THAT IS WRONG!

The 240 volts measured between the two wires comes from a single phase, not two phases. [Two-phase is an industrial transmission and power system utilized in only two parts of the United States, and the two phases are 90 degrees out of phase with each other.]

Power flows in a circle, through the transformer windings and the load in series.

The "return" is a matter of perspective, depending which of the two wires you designate as the "source"! As neither of the "hot" wires in a 120/240 Volt system is grounded in the United States, it is a misconception to speak of one wire as if it were a high pressure hose, and the other a drain.

What would cause a short periodic low hum to come from a circuit breaker?

A short periodic low hum from a circuit breaker could indicate loose connections within the breaker or surrounding wiring, internal mechanical issues within the breaker itself, or electromagnetic interference affecting the breaker. It's recommended to have a qualified electrician inspect the breaker to determine the exact cause and address any potential safety hazards.