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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 method can be used to control the speed of rotation of a 3 phase induction motor?
USE VARIABLE SPEED DRIVE (VSD) OR ALSO CALLED VARIABLE FREQUENCY DRIVE (VFD). THE PRINCIPLE IS TO VARY OR CHANGE THE FREQUENCY WITHOUT AFFECTING THE VOLTAGE. THIS IS ONE SOLUTION TO ENERGY MANAGEMENT AND COMBINED TO BUILDING AUTOMATION SYSTEM OR BUILDING MANAGEMENT SYSTEM.
A Unitary PLC is a Low Cost PLC used generally in small machines as it has a very low input/output count.
Still Need More Info XD
What is a circuit connected to the Earth called?
Grounding?
AnswerIf a line conductor is unintentionally connected to earth, then it is an earth fault.
What is the difference between Air circuit breaker and Vacuum circuiut breaker?
"Air" and "Vacuum" describe how the breaker extinguishes the arcing current. An Air breaker opens far enough that the dielectric strenght of air is enough to extinguish the arc. A vacuum breaker's contacts are in a vacuum. Oil breakers use oil. SF6 breakers use SF6 gas to extinguish the arc.
What is the difference between power and current?
It's the difference between pressure and flow. The pressure is measured in volts, and the current in amps.
Current is the flow of electrons.
Power=VIcosϕ
V=voltage
I=current
Cosϕ=cosine of angle between V and I
AnswerCurrent is a drift of electric charge, expressed in amperes. Power is the rate of doing work, expressed in watts (equivalent to a joule per second).
What is difference between transformer and power transformer?
In electricity supply systems, a 'power transformer' is a category of step-up or step-down transformer used in the high-voltage transmission and primary distribution systems. Step-down transformers used in the secondary distribution system are called 'distribution transformers'.
A power transformer is designed to handle large amounts of power (as the name implies) and usually converts voltages; they are used in power supplies and in electrical supply.
Transformers have three main functions in electronics; impedance conversion, voltage conversion and isolation. Because of these three applications, there are specialist types of transformers. For example, signal transformers are designed to match impedances - for example, between a record cartridge and an amplifier.
You need to know the resistance. Ohm's Law: Current = Voltage (in volts) divided by resistance (in ohms).
What is potential difference or voltage?
If you take two different nodes in a network and if you find the difference in voltage for those nodes then it is known as potential or voltage difference. Here the reference is not taken. But if you find potential difference between a node and its respective ground it is known as voltage at that node here reference is ground potential i.e zero.
Answer'Voltage' is synonymous with 'potential difference'; they both mean the same thing. And it is important that these terms are not confused with 'potential'. So, it is incorrect to say 'voltage difference' (which would mean 'potential difference difference'!), or to describe a voltage as existing 'at' a particular point, or 'with reference to', for example, earth or ground.
In very simple terms, if two points are at different potentials, then there is a potential difference (or 'voltage') between them. A potential exists when work is done moving a charge to a particular point; the greater the work, the higher the potential. 'Potential' is roughly equivalent to the potential energy gained by an object when it is lifted against the force of gravity.
Think of it this way: 'potential' is equivalent to 'height', whereas 'potential difference' (voltage) is equivalent to the difference between points at different heights.
What is the formula to calculate magnetizing current on a transformer?
Measure the primary inductance with the secondary open. Then use 6.28FL (F= frequency, L=henries) to find the reactance in ohms (unless it's a tiny transformer the dc resistance can be ignored). Once that's found use ohm's law I=V/R. If you don't have an LCR meter simply measuring no-load current will also work. If you have no meters you're in for alot of guess work as you need to know the permeability of the core material at the particular flux density/voltage it normally runs at.
How do you convert mechanical power to electric power?
Electrical Power equation: P = I x V (Electrical power = Current x Potential Difference) Hence if one has a Current in Amps (A) and a Potential Difference in Volts (V), these two values multiplied together give the size of the electrical power, P in Watts. 1 Watt is also equivalent to 1 Joule per second. Hence the units Watts maybe replaced by J/s or Js-1. Also, Using Ohms Law V = I x R (Potential difference = Current x Resistance) The electrical power equation maybe re-written: P = I x I x R = I2 x R = I2R (using V = I x R) or P = (V/R) x V = V2 / R (using I = V/R)
How do you determine the amperage given the voltage and the wattage?
Divide the power in watts by the voltage in volts to get the current in amps.
The unit of measure of inductive reactance?
The unit of measurement for inductive reactance (XL) is the ohm.
What is the use of circuit maker?
Oh my god, you are so stupid, the use of circuit maker is to provide students with jolibbee is fun to eat at whenever i go for long walks on the beach and sometimes i run sometimes i hide and i wish that the mistakes are . But basically where are you Gilian Uy?
The 555 timer is a device that allows you to provide a timing signal to a controlled circuit. You provide an RC or other type of tunable circuit. Once triggered, the 555 will provide an output of a set duration. Depending on configuration, it can also be used as an oscillator, or as a flip flop.
You don't need the voltage to calculate that. Just use the product-over-sum formula (for two resistors):
R = (R1 x R2)/(R1 + R2)
Where R is the equivalent resistance, and R1 and R2 are the individual resistances.
Why do you have to find RMS value?
Root mean square (average ***) voltage
Because ac (alternating current) does not warm up a lamp, heater, etc. as well as a direct current of the same value as the peak ac, we need to work out how to find the equivalent dc (direct current) voltage for the ac situation.
The r.m.s. value of an alternating current or voltage is the value of direct current or voltage which produces the same heating effect.
For a sine wave, the r.m.s. value is 0.707 times the peak value, or, conversely, the peak value is 1.414 times the r.m.s. value.
Peak voltage
Peak voltage is measured from the zero axis to the top of the curve. So, in the case of the UK mains supply, where the average r.m.s. voltage is 230 volts, Vpeak = √2 x Vrms = √2 x 230 V = 325.22 volts.
Note: The average voltage is always zero.
*** The average value and the r.m.s. value of a sine wave are not the same thing. The average value of a sine wave is 0.636 x the peak value.
Examples of active and passive elements?
active element means that does not work itself it require external power source for working ie electricity or other
and passive element means that work ifself does not equire external power source for working ie electricity or other
eg. active- compressor need electricity, also tv,computer etc
passive- thermometer sens temperature itself (mercury thermometer)
What is the purpose of a inductor?
The purpose of an inductor is to store and release energy in the circuit usually in order to induce a phase shift in the voltage or current passing through it.
Inductor stores energy in the magnetic field.
What is the use of bay in substations?
bays means how many
accessories are connected with bus bar for example 28 bays mean 6GTs, 5 STs, 2 bypass,one bus coupler and 15 feeders et c.
If you touch a power line do you get shocked?
yes you will you could die or could get severl injuries.
What is function of auto transformer?
A transformer is a device that changes an electrical voltage or current from one level to another. (In radio frequency applications, it is used to couple the RF electronic circuits.)
Transformers are used to:
- Convert high voltage alternating current (AC) to desired low voltage alternating current (AC). Such transformers are called step down transformers.
- Convert low voltage alternating current (AC) to desired high voltage alternating current (AC). Such transformers are called step up transformers.
- Electrically separate one part of the circuit (or any other electrical system) from the other part, termed as 'electrical isolation'. Such transformers are called isolation transformers.
The transformation may involve the loss of some power as waste heat.
(see related question)
What is the power when a voltage of 120V drives a 2-A current through a device?
Power is volts time amps, so 120 V time 2 A = 240 W. That is, of course, assuming that the voltage is DC, or the load is purely resistive. If there is any capacitive or inductive reactance in the device, and the voltage is AC, the true power will not be equal to the apparent power because of a phenomenon called power factor due to phase angle of voltage not being equal to current.
Define the term critical field resistance?
critical resistance is the maximum resistance beyond which the generator failed to exite. it can b found form the occ of the generator.
What is the difference between Auto transformer and Power transformer?
An auto transformer has one winding with the output being tapped at some point and therefore has no isolation between primary and secondary. This may make it unsafe or illegal in some applications. A common power transformer has separate windings.
I think you mean megohm-meter or "megger" which is a high voltage, low current electrical insulation tester.
