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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 are the advantages and disadvantages of a double pole circuit?

A double pole switch can be used in either a 240V application where you'll need to disconnect 2 "hot" lines, or it is useful when switching a light from 3 different switches.

Disadvantage?

I suppose it could be a little confusing to face all those contacts on a double pole switch.

What are multirate systems?

Digital transformation of the sampling rate of signals, or signal processing with different sampling rates in the system.

What cause electrical shock volts or amps?

They both do. Voltage is a measure of electrical pressure. Amperage is a measure of electrical flow (current) (amount of electricity flowing). High voltage by itself will not kill you but will leave a nasty taste in your mouth. At the right pressure your heart can be stopped though by a single amp.

What is the amp rating for a 208 Volt 100 VA transformer?

Is 120 V the primary or secondary voltage? If the primary (input) voltage is 120, then at full load the transformer will draw about 0.42 A from the line, and the current delivered to the load depends on the secondary (output) voltage. If the secondary (output) voltage is 120, then at full load the transformer will deliver about 0.42 A to the load, and the current drawn fom the line depends on the primary (input) voltage. amps = watts / volts So, for instance, if your transformer has a 120 V primary, and a 24 V secondary, as you might find in your AC unit or furnace: Primary current (at full load) - A = W / V A = 50 / 120 A = 0.4166 Secondary current - A = 50 / 24 A = 2.08

What is one horsepower?

One horsepower is equivalent to 746 watts ( = joules of energy per second) or 550 ft.lb (force) of work per second.

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The horsepower or hp is the Imperial unit of measurement for power.

"Power" is the scientific term used to describe "capacity to perform some work".

These days, in most countries, it has been replaced by an SI unit, the watt (or, in practice, kilowatt).

The term brake horsepower refers to the rated output power of a machine, which is not to be confused with the amount of input power it requires to be able to generate that amount of rated output power.

In the case of a car engine, the brake horsepower (or kilowatts) is the power remaining after all the losses have been taken into account. (Heat emitted, gearbox friction, etc.) In other words, output power (brake power) is input power minus losses.

For more information see the Related link shown below.

What happens when a high AC voltage is used on a low DC voltage motor?

Depending on the type of DC motor, it will either run normally or just heat up and make noise.
i think the motor will rotate to and frow.means it will rotate in clycle.it will complete half cycle.and after it will complete its other half cycle in anticlockwise direction.

Why silicon diode require 0.7v drop across it before it start conducting?

A: Actually it begins to conduct almost as soon as there available current. but the current is such a low value that it is considered not to be conducting at all. And the 0.7 volts drop is a chosen value to indicate that the diode is fully conducting and the voltage drop across is .7 volts there about. It can have any value lower then that and it all depends on the current flowing at the time.

What is differential transformer protection?

The current input (primary) to a transformer is proportional to the output (secondary) current.

Differential protection relays monitor these via current transformers (CT).

The percentage of difference between primary and secondary can be adjusted.

If it is over the seting the relay will trip the primaryand secondary feeder breakers.

Thus indicating an inbalance between internal phasewindings and or shorts to earth.

How many mega ohms in an ohm?

A megohm is 1000 kilohms.

So 295k is 0.295M

Are arc fault breakers required on service upgrades?

They may or may not be required for all living spaces where you live when upgrading the panel. Call your local inspector to find out. In my area they are not required on an upgrade but I always install them in bedrooms, closets, living rooms, den, sun room, breakfast room, dining room, libraries, any place people gather may require them. AFCIs will not be required in bathrooms, kitchens, laundry rooms, unfinished basements, garages, attics or outdoors. I personally install them when I upgrade a service panel. They are a great safety device that will protect the people living in that home. I also recommend and install GFCI outlets where needed if the homeowner agrees.

Can you use 120 vac 60 hz drill in a 240 vac 50 hz power outlet?

The voltage is OK, but certain types of motor can't be run on the wrong frequency. If the appliance uses a commutator motor, like many hand tools, it would probably be OK.

Can an electric soldering iron be used to solder silver?

Soldering SilverNo, it isn't hot enough. IT DEPENDS, if two silver plates are overlapped and then soldered with say electical (Tin/Lead) ie Resin cored solder then YES. But if two silver rods or bars or sheet are to be joined end to end etc then NO. The criteria is STRENGTH of the joining material and of course the COLOUR of the joint. THE process is as follows; Use a very hot Mini- Blow Torch ie. Butane or Propane torch, or Oxy- Propane welder and obtain High Silver content Silver Brazing rods (about 20%to 40% silver content) from Model engineering suppliers or Welding suppliers, and Practice first joining small peices of Brass or Copper. The best Silver brazing rods for your purposes are the FLUX-COATED types. EXPERIENCE AND PRACTICE WILL MAKE YOU VERY PROFICIENT.

Yes, if you buy a special type of solder. You can buy different solders for different metals or for different heat levels. Just go to your local hardware or a crafting or hobby store to buy these. The people there can offer great advice on whatever project you are doing.

What are the disadvantages of single phase electricity?

Single-phase power transmission requires a live and a return wire, so power is lost due to current flowing through two wires for each (there is one) driving EMF.

If you add two more at 120 and 240 degrees (one and two thirds of a period), then you get three-phase power. Now, the sum of all currents at either end is zero. When one phase's voltage is high, the resulting current travels down that conductor and returns via a combination of the other two; but these other two currently have a voltage causing that exact same current (split in varying proportions between them) to flow, meaning this current can be considered not to be a "return" of the first phase. You could consider it getting a return conductor "for free".

How do you power a 3 volt DC motor with a 12 volt battery?

you would have to put some type of resistor in the circuit with the motor...the resistor would have to be in series with the motor and would have to be of a high enough value to lower the voltage by 9 volts....There is a formula for working this out but you would need the amperage of the motor to figure this....

What are some examples of indirect contact?

Some examples of disease spread through indirect contact and agents are as follows; Bacteria. E.coli causes food poisoning and urinary tract infections. Mycobacterium tuberculosis causes tuberculosis.

Viruses Influenza virus causes 'flu'. Herpes simplex virus causes herpes.

Protozoa Plasmodium causes malaria.

Fungi Tinea causes ringworm.

Can you touch 220volt line not touching the ground?

You need to get an electrician to put in a proper grounding rod. You don't want to become the path to ground and it sounds like that may be possible if unlikely with you current grounding situation. The problem may manifest itself else where in your house, such as a shower for example. I saw this very problem with a faulty ground in Florida.

Does a transformer changes the frequency of incoming supply?

Yes the transformer effects the incoming frequency supply. This frequency is dependent on the core lamination of the transformer the weightier the core lamination the lesser will be the frequency we get and vice verse..

What voltage range should be used when using a digital volt meter or digital multimeter to measure standard house voltages in the United States?

If your meter lacks an auto-ranging function (many inexpensive units lack such a feature), you must set the range so that the maximum value is greater than the conventional voltage levels in your house. In the United States, the common voltage level is 120 volts RMS, although many homes are equipped with 240-volt service, to accommodate certain appliances, like clothes dryers. (The 240-volt service is really two 120-volt legs.) It's a good idea to set the range higher than expected initially and then adjust it down once you've determined what ballpark you're in. This practice protects you and the meter from dangerous, unexpected over-voltage conditions.

What is the relationship between voltage and current?

You need to figure in resistance also. The formula is I=E/R. Current (I) = Voltage (E) divided by Resistance (R). At the same resistance, if voltage goes up, so does current.

Alternative Answer

The ratio of voltage (U) to current (I) is called 'resistance', i.e: R = U/I. If this ratio is constant for variations in voltage, then the circuit is said to be 'linear' or 'ohmic', and obeys Ohm's Law. If the ratio changes for variations in voltage, then the circuit is said to be 'non-linear' or 'non-ohmic', and the circuit does not obey Ohm's Law. As most circuits are non-linear, it is clear that Ohm's Law is not a universal law.

How many amps will a 750kva electrical transfromer carry?

It depends on the incoming primary voltage. For a 5kva utility transformer receiving 15,000 volts on the primary the current drawn would be one third of one amp to give you an output of 5,000 VA (watts). Just remember this, volts x amps = watts or volt amps.

What power generated in wind power generation AC or DC?

Any generator that rotates will naturally generate AC power into the stationary winding. Wind generators are (all I believe, but could be wrong) induction machines, meaning an AC source is applied to the field and an AC output is generated in the stator. Just like an induction motor, the machine operates with some slip (the rotor speed + the field power frequency = the stator power frequency). If the machine is turning above synchronous speed (so the slip is negative in my equation), the machine will be generating power instead of using it.

Difference between ac and dc bridge?

DC Bridge... We use DC supply, Detector is also a DC current detector and we use only resistive components no need for wegner's earthing device balancing time is comparatively less.. where as in AC bridges opposite of above. i.e. AC supply, AC current detector resisitive+ reactive componants need for wagner's earthing device and balancing time is high as we use AC supply..

Where do you find the wattage rating of a light bulb?

On the end of any light bulb except for the fluorescent type there are numbers on the end of light bulb. The number will be followed by the letter w I.e.(65 w). W represents watts-amount of power used. On fluorescent light bulbs the curly cue ones it will be around the base where it screws into the socket.

What wire size is needed for 30 amp load for 200 feet?

The minimum wire size for a 30 amp load is 10 gauge copper or 8 gauge aluminum. Assuming a 120VAC circuit and to maintain a maximum 3 percent voltage drop from load to panel, upsizing to 4AWG wiring would be the best selection for this circuit.

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An accurate answer can not be given because the type of system has to be stated. Single phase or three phase and a voltage also has to be stated to be used in the calculation for sizing of the conductor.

A #8 copper conductor will limit the voltage drop to 3% or less when supplying 30 amps for 150 feet on a 120 volt system.