Electrical Engineering

A system which can accommodate large inter-area transfers is generally more

robust and flexible than a system with limited ability to accommodate inter-area

transfers. Thus, transfer capability can be used as a rough indicator of relative

system security.

Basically power is the work done per unit time. So anything that is utilizing energy has a power consumption or production. So electric power is the electric energy consumed or produced per unit time.

The "flow of current" is considered to be in the opposite direction.

If a load takes 50 kW at a power factor of 0.5 lagging calculate the apparent power and reactive power Answer: Apparent power = Active power / Power Factor In this case, Active power = 50 kW and power factor = 0.5 So Apparent power = 50/0.5 = 100 KVA

Devices such as transistors, IGBT, thyristors in order to protect them the rupture time is in msec. HRC fuses rupture time is more and the current for rupturing is also high making it suitable for motors/resistive loads.

If the input resistor is 3k ohms and the feedback resistor is 33k ohms in an inverting amplifier the voltage gain is -11, the ratio of 33 over 3.

Consider this... The negative input terminal is a virtual ground, assuming that the positive terminal is tied to ground (usually) through a resistor. That means you have a simple voltage divider between output and input, and the output will be whatever it takes to get the common point (the negative input) to be zero. From there, its all just Ohm's law.

yes.it is used to find self-inductance and internal resistance

You need to understand the difference between power - as in watts - and energy - as in Watt hours.

Watts/kiloWatts only tells you what it's doing at the moment, at that very instant. While Wh/kWh tell you the sum of what it's been doing over a certain time.

1 kW = 1000 w

So 90 W / 1000 W = 0.09 kW

As soon at the light is turned on, the lamp starts to use energy at the rate of 90 W = 0.09 kW

If you leave it on for 12 hours it will have used up 0.09 x 12 = 1.08 kWh

Otto Blathy.

A high-voltage circuit breaker's trip coil is normally operated from a d.c. supply -provided by a bank of batteries located in the substation. This ensures that, in the event of a total loss of a.c. power to the substation, the protection system remains effective.

Rotors used in Synchronous alternators can be classified into 1)Salient and 2)Non-Salient Pole Rotors.

Salient pole rotors are used in application with speeds from 100 to 1500rpm. They are alternative known as "projected pole" type of rotors. The poles mounted on the rotor are made of laminations made of steel. The poles are connected to the rotor shaft by means of dovetail joints. Each pole has a pole shoe around which the winding is wound. The salient pole rotor is generally used in applications where the prime mover is a hydel turbine or a combustion engine which have low or medium speeds. Salient pole rotors usually contain damper windings to prevent rotor oscillations during operation.

Non-salient pole rotors are generally used in application which operate at higher speeds, 1500rpm and above.

The prime movers in these applications are generally gas or steam turbines. These are sometimes known as "drum rotors". The rotor is a cylinder made of solid forged steel. The slots on which the windings are fixed are milled on the rotor. The number of poles is usually 2 or 4 in number. Since these rotors are cylindrical, the windage loss is reduced. The noise produced is also less. These rotors have higher axial length. These rotors do not need damper windings.

Capacitors store charge. There are many applications for their use. There is no set amount of capacitors in a circuit since it is application dependent.

They are based on the air pressure within the tank. They come on then the pressure drops to a pre-set point and shut off the pressure raises to a pre-set point.

Good heat settings, light weight, cool shot function, long lasting and powerful motor and a good price and warranty. Look at the Karmin salon pro hair dryer, it has pretty much what all of them should have.

Mega = million

Megaohm = 1000000 Ohms

Yes and no. A motor will continue to run but at a lower efficiency that when three phase is applied but it is not reccommended leaving it in this condition. It is usually demonstrated in electrical course classrooms to show that it will work. A three phase motor will not start by itself with just two phases connected. Another classroom demonstration is connecting the motor in a single phase supply (two of the three phases) and starting the motor with a rope wound around a pully on the shaft. Pull the rope like starting a gas engine and the motor will run. When a phase is lost the other two leg currents will go high, this high current is what can burn the motor out. Contactors today monitor all three phases and are protected with overload heaters. These heater blocks have auxiliary normally closed (N.C.)contacts on them. The start circuit is wired in series through these N.C. contacts which is in series with the contactor's hold in coil. If any of the three phase legs that are monitored draws a higher current than what the heater blocks are rated for the auxiliary contact on the block opens and de energizes the contactor's coil. This action disconnects the motor's supply voltage from the motor and stops the motor before any damage is done to the insulation of motor's coil windings.

It is like a sine-wave, but in the cycle both halves have the same polarity. Alternate half-cycles are reversed in phase so that they are all the same way. The fundamental frequency in the waveform is double the supply frequency, making the design of the filter easier.

loss of lives

mass destruction of properties

loss of independences

Squirrel cage induction motors.

the coercivity is test by drawing B-H curve.Coericivity is defined as without giving any magnitising force it will produce magnetic field intensity.

A stp-down transformer steps voltage down from a high value to a low value. Transformers only work with AC.

You unplug it and plug it back in

A: Its purpose is to correct the power factor of the line.

hysteresis

When resistors of the same value are wired in parallel, the total equivalent resistance (ie the value of one resistor that acts identically to the group of parallel resistors) is equal to the value of the resistors divided by the number of resistors.

For example, two 10 ohm resistors in parallel give an equivalent resistance of 10/2=5Ohms. Three 60 ohm resistors in parallel give a total equivalent resistance of 60/3 = 20Ohms.

In your case, four 200 Ohm resistors in parallel give 200/4 = 50 Ohms total.