Electrical Wiring

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11,420 Questions
Home Electricity
Electrical Engineering
Electrical Wiring

Which leg is 208 on 3 phase power?

On three phase 208 volts one leg does not have the potential of 208 volts. It takes two legs to provide the 208 volts. The potential is across AB, BC and CA. Voltage to the grounded neutral A-N, B-N and C-N will produce a potential of 120 volts. In a wye configured secondary three phase four wire you have the potential of 120/208 volts.

543544545
Electrical Wiring
Electrician

No objection certificate format for electricity connection?

Owing to the rapid development of newer and newer systems, often city codes and laws cannot keep up with the changes. Such a certificate is given when a certificate of occupancy is held up because the licensing board is unfamiliar with the newest electrical system, and to deny the c of o because of their ignorance is unfair to contractors who have enmbraced the technology. The cert. is usually temporary until such time as the board can know what it is dealing with. It is a stop-gap measure, but needed.

505506507
Electronics Engineering
Electrical Engineering
Electrical Wiring
Robotics

Why hissing noise occur in transformer?

A: Hissing is because is overheating before it destroy itself. But other noises are caused by loose lamination of the core.

B: Hissing noise is produced due to this reason but here is another important point is about frequency (e.g for 50 Hz) the core lamination face attractive and repulsive forces fifty times in one

cycle because frequency is 50 Hz.

Another Answer

The original answer is unnecessarily melodramatic. Transformers are fitted with protective devices that will disconnect the transformer long before a rise in temperature will cause it to 'destroy itself'!

'Hissing', as opposed to 'humming', is usually caused by the ionisation of air in the immediate vicinity of the transformer's high-voltage bushings (hollow insulators). This also manifests itself, after dark, as a blue-coloured luminous discharge.

'Humming', on the other hand, is due to something called 'magnetostriction', a distortion to the core laminations -exactly as described in the original answer, except that the attractive/repulsive forces are twice that of the supply frequency (i.e. 100 times, in the case of 50 Hz), together with harmonics based on that frequency.

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Home Electricity
Electrical Engineering
Electrical Wiring

How many windings does a single-phase transformer have?

Generally a single-phase transformer will have twowindings. One of the Low voltage side and one on the high voltage side. North-American distribution transformers will have three: one high-voltage winding, and two low-voltage windings connected in series.

However...

...a single-phase transformer can also have several primary and several secondary windings. The primary windings can be connected in series or in parallel with each other, as can the secondary windings. For example, taking the primary winding as an example, it could consist of two 120-V rated windings: if connected in series, it could be supplied with 240 V without exceeding its voltage rating; if connected in parallel, it could be supplied with 120 V without exceeding its voltage rating. Multiwinding single-phase transformers allow for a variety of connections.

409410411
Health
Electrical Wiring
First Aid

Can an electric shock cause loss of consciousness?

Yes it can. It depends on the amount of voltage that you got shocked with.

Electric shock can put the heart into asystole (absence of heart contractions). The heart will often resume its rhythm, but the accomanying respiratory arrest lasts longer, and can then lead to a second cardiac arrest due to lack of oxygen.

Also, all electrical burns are considered to be worse than look externally (they can burn internally as well).

377378379
Consumer Electronics
Home Electricity
Electrical Wiring

Should you wire a pool pump to 110 or 220 volts?

The most important thing for safety is to wire the pump to the correct voltage marked on the pump.

All else being equal (i.e. the cost of the pump), use 220 -- the higher the voltage the less electricity lost to resistance and heat.

ANS 2 Most modern pool or spa pumps are convertible (at the motor connection) Connecting to 220 is definitely more efficient.

Ans 3: 110 v is safer, with a lower risk of shock. For a pump of 1 HP or less the power lost in the wiring is very small if the right wire is used.

361362363
Travel & Places
Mexico
Electrical Wiring

What electrical converter do you need for Mexico?

Most places in Mexico adhere to the NEMA 1-15 (2 flat pins) standard. Some others use the American-adopted NEMA 5-15, which includes the third, ground pin. If you are from the U.S. you shouldn't have any trouble to plug your appliances/electronics, but in case your appliance has three pins, you should bring a converter just to be on the safe side.

If you have the European Standard or any other type of connector, you should buy a power converter, as the power grid uses a 110-120 Volt and most European appliances would not charge or work properly.

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Home Electricity
Electrical Engineering
Electrical Wiring

What can you use on wires if you don't have electrical tape?

It depends on the voltage on the circuit. If it is 24 volts or less and the circuit is protected by a current limiting device, it is considered Safety Extra Low Voltage, and one can use any insulating material desired. For voltages above 24 volts, only insulation materials approved by a safety testing agency such as Underwriters Laboratories (UL) or Canadian Standards Association (CSA) should be used. This may include friction tape, heat shrink tubing and "liquid tape" (a plastic that is painted on). Wire connections may be made with insulated terminal strips and terminal blocks or insulated wire nuts; no tape is needed for such connections.

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Home Electricity
Modification of Old Electrical Work
Electrical Wiring

What is a one pole 2 gang switch?

Typically the number of poles represents the number of sources being switched. In a normal household ON/OFF light switch the single pole is the HOT wire (Black). The most common single pole switch is also single throw. The ON/OFF switch described above. This switch is abbreviated SPST. You could also have a single pole double throw switch (SPDT). and other variants on the same theme. The term gang is usually used to describe multiple switches in the same electric box. For example, if you had 3 switches together with a single switch plate, the switch plate would be described as a 3-gang switch plate.

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Home Electricity
Electrical Engineering
Electrical Wiring

Is 13.8kV phase to phase voltage?

There is no such thing as a 'phase-to-phase' voltage; the correct term is 'line-to-line' voltage. Whenever you mention a value of voltage for a three phase system, it is considered to be a line-to-line voltage unless it is stated clearly that this is phase voltage (line to neutral) voltage.

(The reason that there is no such thing as a 'phase-to-phase' voltage is because phases exist between, or 'across', line conductors or between a line conductor and a neutral.) That is a world wide practice for electrical power engineers.

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Home Electricity
Electrical Wiring
Electrical Troubleshooting

How many amps does a single phase 115 volts 1 hp 60hz pump draw?

Since one horsepower is 745 watts, a 115 volt 1 hp motor would pull about 6.5 amperes, depending on power factor.

Note:

That may be a theoretical value. However, practically speaking, single phase A.C. motors are notoriously inefficient. That is the reason the National Electrical Code lists the full load current of a 1 HP, 115 volt motor at 16 amps. That value is considered nominal and can vary depending on motor design. That value does not begin to factor in inrush current.

The best advice is to utilize the manufacturer's motor nameplate value.

327328329
Science
Electrical Engineering
Electrical Wiring
Energy Conservation

What is electric ghost power?

This is also known as phantom power or vampire power. Even though an electric device is turned off, it is still drawing a small amount of power. A television, for example, continues to draw power so that it can sense the remote control to turn it on, or to keep the time.

Other examples are chargers left plugged in for telephones, video games, etc.

327328329
Home Electricity
Home Appliances
Electrical Wiring

How many watts of power does an electric clothes dryer use at 18 amps from a 240 volt outlet?

The formula you are looking for is W = I x E. Watts = Amps x Volts. W = 18 x 240 = 4320. Your dryer is rated at 4320 watts.

However, just because your 240 volt outlet is rated at 18 amps does not mean that is what your appliance will draw.

If the appliance is listed (by the manufacturer) as 1500 watts, then 1500 / 240 = 6.25, would mean that it will draw 6.25 amps at 240 volts.

Note:

Within the United States, most regular size electric dryers require a 240 volt, 30 amp power source. In addition to the electric heating element, there is the drum electric motor that must be factored in determining the wattage rating. That is the reason that it is best to use the manufacturer's nameplate rating for the answer to this question.

323324325
Electrical Wiring

What is the Importance of Magnetic Energy?

Modern life as we know it would not be possible without magnetic energy. It is used to generate and distribute electrical power for our homes and factories (generators and transformers). It is used to perform work (motors). It is used in telecommunications (telephones, televisions). The computer you typed your question on could not function without it (switching power supply). It is used to diagnose medical problems (MRI). The ignition system in most cars uses magnetics to provide the spark to run the engine. There are literally hundreds of uses of magnetic energy, these are just a few! Earth's magnetic field allows us to navigate by compass, but more importantly protects us by deflecting harmful radiation. Oh, and how could we live without those handy little refrigerator magnets that we use to stick notes to the fridge?

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Home Electricity
Appliance Voltage and Travel Issues
Electrical Wiring

Will a 12 volt light work with 24 volt system?

It may work but may be brighter than the rating stamped on the bulb or the filament may burn out very quickly, depends on what sort of bulb it is, wherhet is uses a ballast or some form of regulator etc.. its probably best not to try unless your positive it is designed to take double the voltage

309310311
Home Electricity
Electrical Engineering
Electrical Wiring

What is the difference between earth terminal and neutral in a 3 phase system?

The neutral conductor provides a return path for single-phase loads and you would expect to find neutral current flowing as a normal condition.

The ground conductor provides a return path for fault current when a hot conductor accidentally comes in contact with a grounded object. This is a safety feature of the wiring system and you would never expect to see grounding conductor current flow during normal operation.

At one point in the wiring system, the neutral conductor and the ground conductor are connected together, but they still serve different purposes.

301302303
Physics
Electrical Engineering
Electrical Wiring

What is dielectric stress?

The dielectric stress is the stress placed upon a material when a voltage is placed across it.

297298299
Electrical Wiring
Electrical Troubleshooting
Industrial Electricity and Electronics

What is LT panel in spinning mill?

if electrical panel is labeled LT, usually means its a lighting panel

LT means "Low Tension" panel. Not lighting.

Lighting panels are normally known as LDB (lighting Distribution boards)

293294295
Home Electricity
Electrical Engineering
Electrical Wiring

How do you get 480v 3 phase from 220v single phase?

If you were trying to obtain a 220 voltage from a 480 volt three phase system it can be done with a transformer. To take a 220 volt single phase system and change it into a 480 volt three phase system, it can not be done.

Depending on the amount of money you want to spend to make this happen there is a device on the market called a VFD ( Variable Frequency Drive). On the three phase input terminals you apply your single phase voltage. On the output terminals you connect your three phase motor. When run in this configuration there is an internal switch that has to be changed to let the VFD know that it should be looking for only two lines on the input to be hot. Other wise the VFD thinks that there is a line loss on the three phase input terminals and the unit will not start.

Actually, this is not true. You can go from 220 volt single phase to 480 volt three phase but in a rather cumbersome way. You would first need a phase converter - they have solid state VFD's that will go from single phase to three phase or you can build a simple rotary phase converter. After the phase converter, you will have 208/220 volt three phase power. From there you need a power transformer to step up the voltage.

Remember you have to know whether you want delta or wye configured transformers!

291292293
Electrical Engineering
Electrical Wiring
Pneumatics
Machinery and Tools

What is the basic function of a megger?

A Megger is a device that will test the insulation of the circuit it is connected to. It produces a DC voltage to check for leakage current from the conductor to ground. It then will give you the value of insulation in Mega Ohms. Generally anything less than one Mega Ohm per thousand volts is poor insulation. Be careful when using this device because it does produce high DC voltages and it can give you an awakening jolt. It is most commonly used to test the insulation in motors and generators but can be used in many other applications.

Note that the word "Megger" is actually a trade name (hence capital M). The generic name for such an insturment is "high-voltage insulation tester".

Although Mega Ohms is strictly correct, you'll most often hear it pronounced rather more easily as "Meggohms".

291292293
New Electrical Work
Electrical Engineering
Electrical Wiring

What does input volts and output volts mean?

The terminology would typically reference a device such as a power supply, charger, diverter or transformer. The Input Voltage is the voltage supplied to the device to make it work. The Output Voltage is what the device supplies to an application.

For example, a power supply for a laptop might convert 120 VAC to a voltage like 19.5 volts (A Sony Laptop) for charging a laptop battery.

287288289
Electronics Engineering
Electrical Engineering
Electrical Wiring

Can you test connectivity of circuit using DMM?

Yes. There is a sign of Speaker/sound on a side DMM. Move the knob of DMM on that symbol. Now connect one prob of the DMM on one circuit element & one under that(If you are designing the circuit on PCB or plain board). If a sound come out of that then it means that your circuit element & the portion below that are properly connected.

285286287
Home Electricity
Appliance Voltage and Travel Issues
Electrical Wiring

Can a 9 volt motor rotate 9 volt dynamo?

Are you going to use the 9-volt motor as a dynamo, and the 9-volt dynamo as a motor? Yes, the motor can rotate the dynamo because DC motors and DC generators are actually the same thing--they just apply power to the terminals of a motor to make it turn, and turn the shaft of a generator to make power appear at the terminals.

Having said that, if you're going to try to connect the shaft of a 9v motor to the shaft of a 9v dynamo, and use the dynamo to power the motor so as to create a perpetual motion machine...that won't work. The motor wastes a little bit of energy, as does the dynamo. It is possible to build a device that uses a motor to drive an alternator, which is the AC version of a dynamo. You power the motor from the AC grid, and power something that's very sensitive to noise on the line from the alternator. This is called a Motor Generator set, and it's how they powered Cray-1 supercomputers.

285286287
Home Electricity
Electrical Wiring

How do you save electricity at school?

daytime classes windows and skylights

not Microsoft windows btw that will increase energy consumption

283284285
Europe
Electrical Wiring
VW Transporter

What kind of electricity used in train?

Ac current. Ac current is easily controlled for voltage and frequency. The diesel engine runs a generator that generates AC current for use in the electric drive motors on each drive wheel.

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