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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
Why use inductors in transistor amplifier circuit?
Audio power amplifiers usually separate the last inductor in the output stage transmission chain. The last inductor usually receives the most attention when it comes to power efficiency in a circuit.
Since circuits experience opposition to current, especially where current is changing direction, capacitive reactance or opposition needs to be balanced with inductive reactance. This is done with the help of an output inductor for maximum output to be reached.
Output inductors are used to dampen circuit resonance with the help of a shunt resistor. This is especially important in high frequency circuits where stability is a real issue.
What is the power factor of a coil?
Power factor is the cosine of the phase angle between voltage and current. In a purely resistive load, like a toaster, since the phase angle is zero, the power factor is 1. In a theoretically purely inductive or capacitive load, with the phase angle at 90 degrees, the power factor is 0. Power factor is also the ratio of apparent power versus true power, or watts versus volt-amperes.
How do you make a Navigation system?
it's just like an GPS System but it's a different type and made from a different com[any.........lolzz
DC load flow is a method to estimate power flows through lines on AC power systems.
An accurate solution of the power flows on an AC system is a non-linear problem. Consequently it requires an iterative approach and there is no guarantee of reaching a "convergent" solution.
A "DC" load flow uses a simplified, linear form of modeling the AC system. Consequently its solution is non-iterative, and absolutely convergent. It becomes a routine algebra problem, solving multiple equations with multiple variables. It is inherently less accurate than a "full" AC load flow solution, but it is useful where fast, dependable solutions are essential, and the approximation is acceptable. In reality, there is nothing "DC" about a DC load flow. It solves for phase angles (an AC, reactive characteristic); it ignores resistance (a DC characteristic); and it ignores voltage (because the objective is just power flow). It probably derives its name from the similarity between this solution method and the method used to solve a DC system, which is also linear, non-iterative and absolutely convergent.
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What does a fixed resistor do in a circuit?
It resist the flow of current according to the resistance value.
What is function of capacitor voltage transformer?
The function of a CVT is to provide a secondary voltage to equipment that is a direct ratio of a much higher primary voltage. They can also be used to couple communication signals onto transmission lines.
What is the purpose of interlocks fitted to circuit breaker?
Interlocks fitted to breakers suggest that a load is supplied from two separate sources. An example would be where one breaker is supplied from a utility source and the other breaker will be supplied from a generator source. To prevent both breakers from being on at the same time to supply the load, an interlock is placed across both breakers. This allows only one breaker to be on at a time. Manual interlocks allow a person to make the decision as to which power source will supply the load. Automatic transfer switches have built in interlocks and will sense where the source power is coming from. This type of system switches from one electrical source to another without any human intervention.
What happens if field winding of a running dc shunt motor suddenly breaks open?
when the field winding of a running dc shunt motor suddenly breaks open the motor fails to run because in the motor the stationary winding is armature and rotatory is field winding
What is the power factor of an resititive load?
Power factor is the cosine of the phase angle between voltage and current. In a resistive load, current is in phase, i.e. with a phase angle of 0 degrees, with respect to voltage. Cosine (0) is 1.
How do you calculate load in KW?
You have to know 2 things in order to perform the calculation. You will need to know the power (KW) and either the amps or the voltage. If you know voltage you can determine amps and if you know amps you can determine voltage. However with solely the KW you do not have enough information to calculate either. Here is the formula:
1 Phase: KW = (E x I x pf)/ 1000
3 Phase: KW = (1.732 x E x I x pf)/1000
Where E is voltage, I is current, and pf is Power Factor
How do change a 50 watt fluorescent bulb?
If it's a long, STRAIGHT bulb...grasp with both hands - one at each end of bulb, and gently TWIST bulb toward you until it comes free of lamp. Replace by gently TWISTING new bulb back in - but in the opposite direction (counter or clock wise). If the bulb is ROUND....simply unscrew it by gently turning counter clock-wise.
How do you calculate KWH by KW and Running Hours?
To calculate kWh from kW and running hours, you can use the formula: kWh = kW x hours. Simply multiply the power in kilowatts (kW) by the running time in hours to get the energy consumption in kilowatt-hours (kWh). This formula helps you determine the total amount of energy consumed by a device or system over a specific period.
What is the new colour code for wiring in a three phase four wire system?
The new colors for three-phase systems vary for each country. For example for L1, L2, L3, Neutral respectively: In the United States of America they use Black, Red, Blue, White or Gray.
In Canada they use Red, Black, Blue, White.
In the UK they use Brown Black Grey, Green/Yellow.
For more information see the Related Link shown below.
What is the maximum absolute value reached by a voltage or current waveform?
define the maximum value of an ac wave form
What is the use of voltage divider circuit?
Biasing-Application of suitable DC voltages to operate our amplifiers in desired region of operation(say active or saturation or cut-off region) complying our needs.However in order to maintain a constant Q point irrespective of various external factors,hence it again comes to the need for biasing that compensates the change in external factors suitably thereby maintaining a constant Q-point. Voltage divider bias or self bias is a process of suitably biasing amplifier by connecting two resistors in series in the answer. By proper selection of resistors R1 and R2, the operating point of the transistor can be made independent of β.
Why generally the voltage is applied to HV side?
Lower voltages are required if connected to the low voltage side. The testing facility may not have a gen set large enough to test from the high voltage side.
What to consider before synchronising two generators?
You adjust the voltage and RPM on the second generator to be slightly higher than the first. How much higher depends on the system and generator design.
While monitoring a synchrometer, you pick a relative phase position (again, depending on design) and close the second generator to the first at the selected moment in phase/time.
You immediately monitor and adjust power and vars to make sure the second generator is not too over or under loaded.
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Paralleling generators
The following is for three phase manual paralleling of two generators. Today's control systems will sense and do this operation automatically but the general process is the same. There are a couple of factors that have to be met when paralleling generators. The process of paralleling generators is called synchronization. What this means is that both generators have to be in phase with each other and running at the same speed. The generator that is running is called the lead generator and the one that you are trying to parallel is called the lag generator. There are two types of instrumentation used in synchronising, one is a light bank and the other a bit more sophisticated is a synchroscope meter. The synchroscope indicates whether the lag generator is faster, slower or in phase with the bus. The lag generator is brought up to speed just under the RPM of the lead generator. The synchroscope will be revolving very slowly in a clockwise rotation at this point. When the hand on the synchroscope reaches the 11 o'clock position the switch is thrown to bring the generator on to the bus tying the two generators together.
The light system of paralleling generators has lamps hooked in series and connected between the hot lead of the lead generator and the hot lead of the lag generator. When one generator is running faster than the other one, the lights will blink off and on as the generators come in and out of phase with each other. Adjusting the throttle of the lag generator and bringing it closer to synchronise speed will cause the lights will start to pulsate slower and slower until they go off for a period of seconds and then on for a period of seconds. At this point the two generators are electrically paralleled. Count the time between on off on of the lights. At half the off time (zero voltage) throw the switch and the generators will lock together, the two generators will be running in parallel with each other. Manually to keep them paralleled requires a bit of work, as the faster generator will try and take the load and motor the other one. This is where a governor is a great asset. If the generators are tied together out of phase two things could happen. The least problematic would be the generators breaker will trip. The second and most dangerous is if the lag generator is just a little bit out of phase when the switch is thrown, then the generator will be jerked into phase lock as momentary heavy current flows between the two generators. The sudden loading of the generator has been known to break crankshafts of the engine driving it.
I assume the primary has 12 volts applied.
The voltage ratio from primary / secondary is equivalent to the turns ratio = 10/20, so the primary voltage is 1/2 of the secondary voltage.
The secondary voltage is 24.
How do you calculate the top speed of an electric motor?
Yea, but what if you are building the motor yourself and need to know the maximum rpm it will reach.
Is a load and a motor the same thing?
when machine is taking electrical supply and produces flux, torque etc inside and gives mechanical (rotational) output it is MOTOR
but when this motor is connected to some thing which results in drawing current and work to be done, that thing is LOAD
without any load motor has maximum speed and by increasing load speed decreases..
AnswerAnything connected to a supply which draws current is a 'load'. 'Heavy loads' draw a lot of current, whereas 'light loads' draw little current. So a motor represents a load to the electrical supply; this applies whether the motor is driving a 'mechanical load' or not. We use the term 'mechanical load' to describe whatever (fan, compressor, pump, etc.) is being driven by a motor.
