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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 applications of a shaded pole motor?
When the coil in the relay needs to run off an AC signal rather than DC. The shaded pole keeps the relay from "chattering" every time the AC current crosses 0v on the sine wave.
What is the formula for calulating test voltage for Insulation Resistance Checking?
Estimated Insulation Resistance of a cable:
IR = K log (D/d)
K = specific insulation resistance in megohs - 1000 feet at 60 Deg. F (K = 2000 for PVC; 50,000 for EPR; 100,000 for XLP)
D = diameter over insulation
d = diameter under insulation
IR = insulation resistance in megohms - 1000 feet. Note that IR is inversely proportional to the cable length. So don't forget to divide the calculated IR for 1000 ft. by your Cable Length (L) then multiplied by 1000.
Be advised that in the real world, the measured IR may not be anywhere close to the calculated IR due to extraneous influences such as humidity, temperature, dirt, etc.
How is voltage measures use of load measured in a circuit?
a little thing called an ammeter, you clip this onto your circuit and it measures the voltage!xxx ask again
What are the parts of a direct current generator?
there are many parts of a dc generator
armature,
field coil,
yoke,
body,
rotor and commutator.
What is vector group Ynyn0 in transformer?
it is a star to star connected transformer. It having two neutrals. One is at Primary side and another is at secondary side to balance the loads.
Y= Primary star connection
N=Primary Neutral
y=secondary star connection
n=secondary neutral
and
0=No phase shift between primary and secondary.
So,finally this meaning is star to star connected with two neutrals and zero phase displacement.
Please refer below i detailed some notations to calculate any other vector groups
D= Primary Delta connection
d=Secondary Delta connection
a=Auto transformer
Z=Zig zig connection
11=30 degrees phase shift b/w primary & secondary
1= 30 degrees phase shift b/w primary & secondary
1) Consider capital letters for Primary notations
2) Consider small letters for secondary notations
3) Consider Clock reference at 12.00 for calculation of degrees
I think this procedure is very useful to calculate for other vector groups.
How do you select contactor for motor?
With a contactor we can control the power connection to the motor (power on/off). A typical AC contactor comes with 4 terminals aside (L1,L2,L3,A).
'A' has A1,A2 terminals which are of the magnetizing coil. By magnetizing & demagnetizing A1-A2 coil, power line connections to motor can either be made or broken. This is a simple DOL (Direct On Line) application.
Further, reverse/forward circuits and star-delta circuits can be constructed based on the requirement.
A contactor's role in whatever application is 'making or breaking' the contact.
The coil supply can either be AC or DC.
What is the difference between a tpn mccb and a 4 pole mccb?
The difference between a tpn mccb and a 4 pole mccb is rather negligible. The only real difference is that a 4 pole mccb works a little bit faster and allows for a strong network connection. The connection with a 4 pole mccb is just a bit more reliable.
How do you change a 240 circuit to 120?
A step down transformer can do it safely. However there is going to be some loss of efficiency with actual loading so a step down of 1:0.5 ratio can do it the power required is to be implemented.
The statement that current is equal to the voltage difference divided bythe resistance in known as?
Ohm's Law V = I R
Voltage = Current x Resistance
How does a permanent-split capacitor motor work?
This is a piece of machinery similar to a capacitor-start motor and operates on an LC circuit. One of the main differences, however between the two is that there is no centrifugal switch and instead of being initiated by an inital start winding montion, the permanent-split capacity motor is permanantly connected to the power source.
What is the importance electric motor?
The main reason is the motor’s variable speed behaviour. When the voltage applied to the armature of a DC motor increases, the
motor’s speed increases correspondingly.
Another reason is the DC motor can develop full torque from zero up to its base speed. This constant-torque characteristic allows DC
motors to be used on applications such as conveyor belts, elevators, cranes,extrudesand mixers,amongstothers. The full torque
from zero speed is useful when the application needs to be stopped when fully loaded, and then got moving again
How do you calculate 3 phase power with a power factor?
To calculate three-phase power with a power factor, you would use the formula: P = √3 x V x I x PF, where P is power in watts, V is voltage, I is current, and PF is the power factor. Multiply √3 (1.732) by the voltage, current, and power factor to determine the power in watts.
How do you size a generator for a motor?
Make two lists. List the appliances you want the generator to run when commercial power is available. Next, list the appliances you want the generator to run when commercial power is NOT available. Determine the wattage of each appliance and then add them together for the first list. Repeat this for the second list. This will give you total wattage for each list. This will help you determine the size of the generator needed to power your devices when commercial power is available and for when commercial power is not available.
Understanding the wattage values of each appliance is important for correctly choosing the wattage values to add together to get the total estimated wattage needed to power your appliances.
If all of your loads are resistive, such as incandescent lamps and heaters, you simply add up their wattage to get a total. However if you have electric motors which will cycle on and off or appliances like a heat pump or an air conditioner, you must take into consideration the required starting current of these devices. The start up current of these devices can be up to 6 times the running current.
Starting Watts are the power the generator can produce for short periods of time.
Running Watts are the power the generator can produce continuously.
Here is an example of how to determine generator size:
Question: I am considering the purchase of a standby portable generator to power key appliances in the event of a power loss which sometimes occur during winter snow storms. Do I just add up the total number of watts required by the appliances I want to run? In the event of a winter storm interruption of electricity, I am looking to keep the refrigerator/freezer running, along with the blower motor of a pellet stove, a few electric lights, and a radio. All else can wait until power is restored!
Answer: The total estimated wattage of 1840 watts is needed for the radio (15 watts), the motor (575 watts), and the refrigerator/freezer (1250 watts). To this I added 500 watts for five 100 watt light bulbs for a total of 2340 running watts. Next I added the starting watts of the motor to the running watt total of 2340 watts, to get the total estimated wattage of the generator needed to power all these appliances simultaneously. For example, assuming the starting watts needed for the blower motor are 3 times its running watts (3 times 575 watts = 1725 watts), so the total estimated wattage of the generator needed to power all these appliances simultaneously is 2340 running watts plus the 1725 starting watts of the blower motor, for a total of 4065 watts. The generator needed to run all these appliances simultaneously would need to have a maximum power output of at least 4065 watts.
Note: The maximum power output is also called short time watts, peak watts, maximum watts, surge watts, and starting watts. It's helpful to keep this in mind when reading portable generator wattage ratings.
Why is the voltmeter connected in parallel but the ammeter connected in series?
The Voltmeter is used to measure the electrical potential difference between two points...
so it's no use to connect it in Series , because the electrical potential difference between two points at the same line is zero ==> the readings will always be zero.
The Ammeter is used to measure the electric current in a circuit...
so it's no use to connect it in Parallel , because you want to know the current flowing in this wire.
note
the internal Resistance of the Ammeter is very little
and very high for the Voltmeter --> so they will not affect the circuit.
AN RF Isolator is really a three port device called an "RF Circulator" in which one port is always terminated correctly with a suitable load. RF Isolator are usually passive and are bandwidth limited.
Typical use: It used in the output of a RF Transmitters High Power Amplifiers but before a BP/ HP filter and the antenna.
Typical Function: To isolate a TX RF Power Amplifier output from receiving RF feedback from external sources. i.e. In this case the RF coupled in from other Antenna systems in close proximity. Such undesired RF feedback would cause intermodulation / harmonics products to be generated within the RF amplifier and consequently be re-radiated out along the the desired RF signal to the antenna and possibly cause interference. Often used on all TX's in two way radios sites to avoid local IM.
SIMPLIFIED: In other words an Isolator passes RF in one direction but attenuates RF in the other direction.
Note: The RF Isolator is slightly non linear and therefore it can cause low levels of intermodulation / harmonics. So it is good practice to place either a basic Band Pass or High pass filter after the RF Isolator to attenuate the unwanted IM products.
Tuning these RF Circulators / Isolators correctly requires a suitable network analyzer or combination of RF Bridge / Spectrum Analyzer with Tracking generator.
A 1.5 hp electric motors uses how much electricity?
it is as simple as this
know your volt (110, 220 ..)
know your amp
from the manufacture sticker usually on the back of the motor
and your load in watts = volt x amp
so if you are using a 1.5 hp motor that is amp rated = 7.0 at 220 v
then your watt = 220 x7 = 1540 watt = 1.54 kw
hope that will help
http://sawdustmaking.com/ELECTRIC%20MOTORS/electricmotors.html
thanks
What will happen too amperage if voltage is increased and resistance remains the same?
Ohms Law says Voltage = Current x Resistance. Hence if voltage rises, so will current.
Is there any transformer working in DC?
It is a fundamental physical fact that transformers can only work if they are fed with a changing or alternating current (ac).
They simply cannot work if they are fed with a constant direct current (dc). There is one type of transformer that can be used in a dc (direct current) circuit if it is "pulsed" dc. The most common application of this is the ignition coil in a vehicle. The coil operates on pulses of the 13.5 Volts dc of a vehicle's electrical system. Depending on the type of fuel and the type of ignition system the car uses, pulses of dc are fed to the ignition coil either from "contact breaker" points or from a solid state "ice" (ignition control electronics) box. Each 13.5 Volt dc "pulse" is stepped up by the ignition coil to generate the several thousand volts needed to "fire" the spark plugs via the distributor. As you asked this question you are obviously very interested in learning more about electricity and the various electrical components which have been invented, such as transformers, so why not go to your local library and find some books about Electrical Engineering to read, so you can learn more about this fascinating and exciting subject?
What is kirchhoff's loop theorem?
a closed path in a circuit in which no circuit element or node is encountered more than once.
Why Reduction in Depletion region width with increase in doping?
Because Reverse bias constrained the majority carries to repel from both side (P side & N side)hence Depletion layer is formed with a large extant of majority carriers hence the depletion region is wider in reverse bias.
Why Carey foster bridge is more sensitive?
The Carey Foster bridge is more sensitive than traditional bridge designs due to its unique configuration, which includes two parallel beams connected by a middle beam. This design minimizes the effects of temperature fluctuations and mechanical stresses, allowing for more precise measurements. Additionally, its ability to balance the strain across its structure enhances its sensitivity in detecting small changes in resistance or displacement, making it ideal for high-accuracy applications in laboratories.
What is the difference between Alternators and generators?
Generators produce electricity as direct current and Alternators produce electricity as alternating current. As alternators produce electricity more effeciently, and they are smaller and lighter and are used in modern vehicles.
A generator creates direct current in the manufacture of power. An Alternator creates alternating current in the creation of power. Alternators can have diodes installed internally so that they have a D.C. output.
Disadvantage of optical fiber communication?
•Only economical when the bandwidth is fully utilised
•High cost of installation
•A lot of hardware at the moment is not compatible with fibre optic cables, they need to be adapted in order to make use of them
What are the different ways of constructing a multiway if-else structure?
If this is a one-off, use either SSI components from your junk-box, or one or more MUX chips, with some outputs wired back to inputs.
If you are making quantities, either use an eprom, burn it to ROM when it's debugged, or use a PLA.
Whichever you do, logical analysis first will probably save time and money in the long term.
