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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 can phase advancers improve the power factor?

PHASE ADVANCER:phase advancers are used to improve the power factor of induction motors.The low power factor of an induction motor is due to the fact that its stator winding draws exciting current which lags behind the supply voltage by 90 degree.If the exciting ampere turns can be provided from some other A.C. source,then the stator winding will be relieved of exciting current and the power factor of the motor can be improved.This job is accomplished by the phase advancer which is simply an A.C exciter.The phase advancer is mounted on the shaft as the main motor and is connected in the rotor circuit of the motor. It provides exciting ampere turns to the rotor circuit at slip frequency.By providing more ampere turns than required,the induction motor can be made to operate on leading power factor like an over-excited synchronous motor.

What safety precautions should be taken during maintanence of a 11000 volt line?

11 kV power lines are extremely dangerous and there are many safety requirements. The main principle is that this work must be done by trained and qualified personnel.

Some of the protocols include always wearing a hardhat and protective boots, and never going near such power alone.

What is Inverse Definite Minimum Time?

(I.D.M.T.) RELAYThe over load inverse time relay is shown in fig 26. It consists of an upper electromagnet that has been provided with two windings one primary and the other secondary. Primary is connected to a current transformer in the line which is under protection and is provided with eight tappings. These tappings are connected to a plug setting bridge by which the number of turns to be used can be adjusted in order to have the desired current setting. The second winding called secondary is energized by the induction effect and is wound over the central limb of the upper magnet as well as it is spread over the two limbs of the lower magnet. By this method, the leakage flux from the upper magnet entering the disc have been displaced in phase from the flux entering the disc from the lower magnet. The deflecting torque is produced on the disc in the fashion as already explained. The spindle of the disc carries a moving contact which bridges two fixed contacts after the disc has rotated through a certain angle which has been set before. Any setting for this angle is possible varying from 0 to 360°. The variation of this angle imparts to the relay, various time settings.

The speed of rotation of the disc is dependent upon the torque which in turn is dependent on the current setting, when the load current increases from this setting it will increase the speed of rotation of the disc resulting into decrease of operation time. Thus the time current characteristics of the relay observe inverse-Square law. The definite minimum time characteristics of the relay are obtained by the use of a saturated upper magnet. This ensures that there is no further increase in f1ux when the current has reached a certain value and any further increase of current will not affect the relay operation. This results in a flattened current time characteristic and the relay obtains its name as Inverse definiteminimum time lag (I.D.M.T.) relay

The current time characteristics of the relay have been illustrated in Fig. 27. It represents the time required to close the trip contacts for different values of over current. Its horizontal scale is marked in terms of current-setting multipliers i.e. number of times the relay current is in excess of current setting

Can be the power factor become negative reading?

Yes, power factor can be negative. That is the case of a generator. Power factor is the cosine of the phase angle between voltage and current, and the cosine can be positive or negative.

Answer

No. Power factor can be 'leading' or 'lagging', but it cannot be 'negative' or 'positive'.

How is dc represented?

DC, or Washington, D.C., is represented through a unique political structure. While it is the capital of the United States, it does not have voting representation in Congress; residents elect a non-voting delegate to the House of Representatives and have no representation in the Senate. Additionally, D.C. has its own local government, which manages municipal affairs. The lack of full representation has led to ongoing debates about statehood and voting rights for its residents.

What does rla and lra mean on an electric motor?

RLA stands for "Rated Load Amperes," which indicates the maximum current the motor should draw under normal operating conditions at full load. LRA stands for "Locked Rotor Amperes," representing the current drawn by the motor when the rotor is not moving, such as during startup or when it is stalled. Understanding these values is essential for selecting appropriate circuit protection and ensuring the motor operates efficiently.

Torque on Ford 302 heads are?

Fist tighten to 50lbs in sequence,rhen to 60lbsin sequence and then to 65-72 ft lbs in sequence. Wait about ten minutes then recheck and tighten to the 65-72 ft lbs.

A circuit has two resistors of equal value in series The voltage and current in the circuit are 20 volts and 2 amps respectively What is the value of EACH resistor?

Ohms law states

Voltage = Current X Resistance, or as commonly represented, E=IR.

In this case plugging in the values (using basic algebra)

20 = 2R

or

10 = R

or as commonly stated

R=10.

So that lets us know the TOTAL resistance of the circuit.

Now, knowing that series resistance is "added", we can calculate the individual circuit resistance.

In a series circuit total resistance can be represented by 'R', and the individual resistance of each resistor can be represented by "R1", "R2", R3", and so forth. In a series circuit resistances can be calculated using the formula: R=R1+R2+R3...

Since we only have the two resistors the formula would be:

R=R1+R2

Knowing that the resistors are equal in value we can assume:

R=R1+R1

OR

R=2(R1)

OR

2(R1) = R

OR

R1 = 1/2R

Given that R is 10 (from above)

R1=1/2 * 10

or

R1 = 5

Each resistor equals 5 ohms

What are different measurements of electricity and what aspects of electricity do they measure?

Here are some common units, and what they measure:volt - voltage

ampere - current

ohm - resistance

siemens - conductance

hertz - frequency

(dimensionless number) - power factor

watt - power

How do you improve the ir value of the transformer?

Moisture entered inside the transformer coil may cause loss of IR value. IR value can be increased by removing the moisture. Keep the transformer in a hot air chamber for sufficient time to vaporize the moisture.

In a circuit if the switch is closed how many volts go across the switch?

For an ideal switch, there will be no voltage drop across it. In reality, there will be a very small voltage drop, and this will be dependent on how well made the switch is, and what it is made out of.

What physical act is required to generate power in commercial generators?

To generate power in commercial generators, mechanical energy is required to rotate the generator's rotor. This rotation typically occurs through the use of a prime mover, such as a steam turbine, gas turbine, or internal combustion engine, which converts fuel into mechanical energy. As the rotor spins within a magnetic field, it induces an electrical current in the stator windings, producing electricity.

What is polemic resistance?

Polemic resistance refers to a form of opposition or dissent characterized by sharp, aggressive, and often controversial arguments against established norms, practices, or ideologies. It typically involves a strong rhetorical approach aimed at challenging dominant narratives or power structures, often in political, social, or cultural contexts. By using provocative language and challenging prevailing beliefs, polemic resistance seeks to provoke thought and inspire action among its audience.

Is the 3 phase connection has a live and neutral?

In a three-phase electrical system, there are typically three live (or phase) wires and usually no neutral wire is required for balanced loads. However, if the loads are unbalanced or if a neutral is needed for specific applications, a neutral wire can be included. This allows for the connection of single-phase loads. Overall, the standard three-phase connection primarily consists of the three live wires.

How to reduce tower footing resistance?

1. Use of short length radial conductors bonded at the injection point. rather than a single long length conductor. This produces the effect of having a number of conductors in parallel.

2. Terminating radial conductors with vertical electrodes. This measure is more effective in low to medium soil resistivity.

3. Using large bending radii when changing the direction of horizontal conductors. Sharp bends tend to increase the inductance.

4. The use of earth enhancing compounds to improve the soil resistivity in the proximity of the conductors which will reduce the tower footing resistance

What is throwaway prototyping?

A prototype is typically build to better understand some aspect of the final project. If you don't intend to use any part of the prototype in the final produce, it can be said to be a throwaway.

What is power factor of resistor?

A resistor doesn't have a power factor. However, if a circuit is pure resistance in nature the power factor will be one when a voltage is applied and a current flows in the circuit. The power factor is a measure of the relative phases of the current and voltage in a circuit.

Where is the best place to put an ammeter in the circuit to measure the current going through the light bulb?

Since (by Kirchoff's current law) the current in a series circuit is the same at every point in the series circuit, it does not matter where you place the ammeter.

What happens if amplifier is connected t a DC voltage?

It will depend on the which kind of amplifier it is ,if it is made from Op amp(Non inverting Amplifier) it will simply amplify(multiply)the signal with a factor depend on the configuration of circuit which is also known as gain of the circuit.For instance if gain is 2(dimension less) and input DC voltage is 2 Volt output would be 4 Volts.

and if it an Audio or RC coupled amplifier output would be zero

Hence i Wrote in the starting "It will depend on the which kind of amplifier it is"

What is standard cell characterization?

Standard cell characterization is determining electrical properties of a circuit (timing, power, noise, capacitance etc) using simulation.

See www.paripath.com, a provider of Standard cell characterization software, for more information.

When would you measure for resistance in a live circuit?

Measuring resistance in a live circuit is generally not recommended, as it can pose safety risks and potentially damage the measuring instrument. However, if necessary, it should only be done with specialized equipment designed for live measurements, ensuring that the voltage and current levels are safe. Typically, resistance is best measured when the circuit is de-energized to avoid inaccurate readings and hazards. Always follow safety protocols and guidelines when working with electrical systems.

What is the current value of a 1960 era zodiac seawolf dive watch?

You can find these for up to $ 900 on the internet and alot has to do with the condition of the watch including the stainless case, movement and dial. You can fugure a good wholesale value of $100 to $ 200 and would probably get close to $ 200 on eBay