Electrical Engineering

350-400Amps

This depends heavily on the intended usage (voltage, power, etc).

If your power source already has the correct voltage but you want to regulate power spikes (e.g. electrical noise in a car), you can use a passive RF filter: basically, an LC low-pass filter element.

If your power source has a higher voltage than the device you intend to drive, there are two options: a passive regulator, built around a power resistor and a Zener diode, for very low to low power systems, and very low cost; or an active regulator built around a 78XX chip (or equivalent), for medium power systems, and somewhat higher cost. The 7805 chip is very widely used to provide 5V, and will always work. The Zener regulator is really the simplest and cheapest way to do it, but it requires you to modelize your power requirements to choose the correct diode and resistor.

If your power source has a lower voltage than the device you intend to drive, there are various chips available, but they generally require more external components like a coil and a capacitor, and require you to do more computations to get right. They also generally cost more.

Transformers are designed for a specific application. frequency IS A MAJOR FACTOR THAT GOES INTO THE DESIGN.

in a dc machine core losses occur both in stator and rortor but stator core losses are negligible as compared to rotor core losses because in stator constant dc flux is given and the statot conductor is stationary so there are no eddy losses and as the flux is stationary there are no hysteresis loassses also but in rotor armature winding is placed so here alternating field is induced which cuts the rortating conductors of rotor thereby inducing eddy as well as hysteresis losses fo any more info. contact zombie

A zener diode has a voltage when it reachesbreak over it may be 5v 12vor other voltage as manufactured. The manufacture will produce a 5v zener or is it? This voltage can change from device to device but the mean or nominal voltage will be as close as 5v as possible. So when buying a 5v zener do not expect 5v absolute but a nominal 5 v

ZENERS are designed for a specific voltage [ THEREFORE NOMINAL] as mentioned above . depends on the voltage required it can be bought within a specific voltage -/+ a % of the breakdown

variation in beta dc with collector current

None what so ever. The cost of changing all of your equipment and new service would be high. The electrical bill is based on wattage used be it single phase or three phase.

This configuration is used to reduce the starting current. Utility companies do not like large motor loads starting across the line. It dips the voltage level of the line. By reducing the starting current to a lower level also reduces the voltage dip in the supply lines.

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It is simple LEDS do need a definite voltage drop to work must have a minimum current to operate. for a 9v battery source and a LED of 3.2v operating at 20ma the solution will be 9v-3.2=5.8v therefore to limit the current to 20ma a resistor of 5.8v/0.02=290 ohms not such an animal so a 270-300 ohms will work. Final note make sure that the LED power is not exceeded 3.2v x0.02ma=63 mw

What is rf transmitter

I=Kva*1000/v*1.732 =500*1000/415*1.732 =500,000/718.78 =695.62 Amps. So max.load of 500kva DG is 695.62 Amps

I think you mean 'turns' rather than 'coils' (a coil is made up of a number of turns). The answer is that, yes, the turns ratio is the same as the voltage ratio, for an ideal transformer.

assuming 5v steady the 2 amps can be virtual zero by reducing the load present

Device for reducing a gas or vapour to a liquid. Condensers are used in power plants to condense exhaust steam from turbines and an in refrigeration plants to condense refrigerant vapours, suchas ammonia and freons. The petroleum and chemical industries use condensers for hydrocarbons and other chemical vapours. In destillation a condenser transforms vapour to liquid. All condensers work by removing heat from the gas or vapour. In some, the gas passes through a long tube of heat-conductive metal, such as copper (usually arranged in a coil or other compact shape), and heat escapes into the surrounding air. Large industrial condensers use water or some other liquid to remove the heat. The term condenser also refers to a device attached to carding machines in textile factories to collect fibres into roving for spinning machines.

extra resistance is added in order to decrease starting current and improve starting torque

increases

This is a transformer built into electrical appliance to make electricity meter to stop reading or made to read in reverse order. This reduces the consumption reading and cheats the system. That is bad.

due to space vector modulation we can eliminate the lower order harmonics

contrary to the belief that the 50-60 Hz is stable in reality it is not frequency changes constantly during the day as power is increased or reduced but the average for a day is pretty much constant. a generating plant is a thermal or hydro machine it cannot responds very fast. so the average is stable for the grid since all plants have reserve spin power available constantly

to calculate kva rating of single phase transformer:

kva rating= Q =Vp * Ip * 10^-3

where,

Vp= terminal voltage of primary winding

Ip= current of primary winding

so,

Q = V * I *10^-3

=2.22 * f * phi *Kw *Aw *delta * 10 ^-3

where,

f= frequency in hertz

phi= maximum flux in weber

Kw=window space factor

Aw=window area in m2

delta= current density in A/m2

but,

phi (maximum flux) =maximum flux density * net area of core

=Bm * Ai

so,

Q=2.22 * f *Bm * Ai *Kw *Aw *delta * 10 ^-3 kva

to calculate three phase transformer,

Q= 3.33 *Bm* Kw* Aw*Ai * 10 ^-3

what is flying capacitor

push button

Percentage reactance of a transformer (or in general, a circuit) is the percentage of phase voltage drop when full load current flows through it, i.e

%X=(IX/V)*100.

Now Short Circuit Current is V/X

So short Circuit current is I*(100/%X).