Electrical Engineering

You may use a filter which will round off the square pulse to sine wave.The higher order the filter the better the SINE wave . The Square pulse and the sine wave must both be tuned to our required frequency

Like most other countries, you will find that in England we use voltages ranging from almost zero to a few tens of kV, depending on the application. ;)

However, assuming you mean the voltage supplied by 3-pin 13A mains sockets (type G) then from 1 January 2004 the mains supply should be 230V (-6%, +10%), 50 Hz (±1%). ie a range of 216.2 - 253V. This replaced the UK's former specification which was 240V ±6% (ie a range of 225.6 - 254.4V). Some "shaver sockets", similar to round 2-pin sockets (type C) found in mainland Europe, will supply 110 V, but be careful since they often have a dual mode 110V/240V.

Static Frequency converter is a static device with power electronic component such as scrs etc

On a per person basis, we do not use more energy now than in in the late 60's due to the advancement of energy saving appliances etc. However, as a whole we use much more energy and the demand is growing at an alarming rate.

Other countries such as China and India where the economy is booming are now competing with us for energy as well. The drastic increase in demand on a global level will contribute to a rapid and steady rate increase as 80% of our energy comes from fossil fuels and other limited resources.

Actually electrical engineering comprises all the subjects basics like electronic,

management, mechanical,computer based subjects through this we can learn all the subjects basics clearly and it is more useful for higher education. the very main advantage of picking electrical engineering is we can able to study any subjects related to research or industrial oriented or business oriented etc.., in our PG. electrical engineering subject is also one of the toughest one in engg stream, if we pick electronic engg we go only by communication or electronic side so my answer is electrical has the upper hand than the electronic engg

If it is a three lead 3-phase motor, it is easy: connect the incoming three leads randomly to the three leads on the motor (one to one) so that there are a total of three splices. The motor will run but possibly in reverse If it runs in reverse, switch any two of the three splices ---- If the motor has more than three leads, and they are not marked, it is much more difficult. You will have to have a working knowledge of how to test the leads and compare the results with the information given on the nameplate

* basic physics -- a voltage applied across a junction or an insulator will produce some current, no matter how small. No perfect insulator exists in electronics.

* defects in manufacturers -- undesirable elements in a junction or an insulator, introduced during manufacturing and stay, will affect the normal current-voltage behavior

* unintended usage -- the voltage or current applied to an electronic component has gone beyond its spec

* damage -- the electronic component has suffered permanent damage due to excessive usage, abuse, or electrostatic discharge.

To use a star delta starter, the motor must be a three phase six wire motor. The extra wires out are the wires that are usually terminated in the motor housing as the star point. The starter, when energized, brings the star contactor in and closes the star point coil ends. An external timer times out after the motor gets up to speed in the star connection and drops the star contactor and closes the delta contactor. When in the delta connection the motor coils are then paralleled to allow the motor to run at full voltage.

A 'balanced' three-phase load, by definition, is one in which the load connected in each phase (either line-to-line or line-to-neutral) is identical in all respects. A single load, clearly, doesn't comply with this definition.

voltage drop is zero bcz in open ckt current will be zero

Armature reaction is the effect of armature flux on the flux generated by the fied windings.
Cross magnetisation and Demagnetising are its consequences.

In essence it is used in applications where it is important that the resistance of a length of contantan wire doesn't change with temperature. As a student the only time I've ever needed this feature is in experiments involving measuring resistance.

A use for constantan wire is in DC Current Shunts. This is a precision low value resistance placed in series with the load in a direct current circuit that is carrying high current. By measuring voltage drop across the shunt, we can measure the current. In this application it is important that the resistance of the shunt does not vary with temperature (the shunt will heat up under full load) otherwise the accuracy of the current reading is compromised. Typically the resistance of the shunt is set to give 60 millivolt voltage drop across it at full current.

A conductor is that one which allows the flow of electric current through it. An inductor is also a conductor but in the form of a coil used in varying current circuits. An inductor's role is not to conduct electricity; it is used in alternating current circuits and control it without much power loss. it is based on self induction.

dc series motor

pass AC voltages.

No, not really. 208V is derived from two phases of a 208/120 three phase power system, while 230V (or 240) is a single-phase power system already. Motors and other loads are usually notrated for both voltages, and could be damaged if fed the wrong one. Of course, other devices are rated for both. If so, it will be listed on the nameplate.

When you pass electricity through wires you warm the wires up. This heat is a total loss of energy. So you want to keep the loss to a minimum. The heating effect of electricity is increased with an increase in amperage (the current). The amount of power that goes through the wires is a function of the voltage x amps. So to transmit a certain amount of power with the minimum heat loss you keep the current down which mean pushing the voltage up. This is why the transmission wires near the generating station carry very high voltages. But these voltages are unsafe for use in domestic circuits so they have to be reduced by a series of transformers from the high voltages in the main lines to lower voltages at substations to even lower voltages in the home.

But transformers are used in many other ways, but basically to change the voltage of the supply. Like your cellphone charger reduces the mains voltage to whatever it is your phone operates on, say 9 volts.

1. It is a static device which transforms the voltage (electromagnetically). In certain cases, the required voltage of a system needs to be increased or decreased, so in those cases a step up/ step down transformer is a must required.

2. Secondly it may be called as a protection device to the electrical network. At times due to heavy electrical faults it trips by keeping the main supply system healthy.

3. Step up voltage was used to Transmit the power to very long distance w/o higher transmission loss.

4. Because of Static device it operating efficiency is 98% compare to any electrical device.

5. Easy control & voltage adjustment.

Converter is AC to DC. Inverter is DC to AC

What is the difference between cylindrical and prismatic battery cells?

Anything that uses electricity. For example, a light-bulb.

DC motor :

-DC (Direct Current) Motors are two wire (power & ground), continuous rotation motors.

-The speed of DC motors is controlled using pulse width modulation (PWM), a technique of rapidly pulsing the power on and off. The percentage of time spent cycling the on/off ratio determines the speed of the motor, e.g. if the power is cycled at 50% (half on, half off), then the motor will spin at half the speed of 100% (fully on). Each pulse is so rapid that the motor appears to be continuously spinning with no stuttering.

Servo Motor :

-Servo motors are generally an assembly of four things: a DC motor, a gearing set, a control circuit and a position-sensor (usually a potentiometer).

-The position of servo motors can be controlled more precisely than those of standard DC motors, and they usually have three wires (power, ground &). Power to servo motors is constantly applied, with the servo control circuit regulating the draw to drive the motor.

-PWM is used for the control signal of servo motors. However, unlike DC motors it's the duration of the positive pulse that determines the position, rather than speed, of the servo shaft.

The secondary current is determined by the load, not by the transformer. For example, if the secondary voltage is 50 V and the load is 100 ohms, then the secondary current will be 0.5 A. If the load is 25 ohms, then the secondary current will be 2 A. It is important that a continuous secondary current doesn't exceed the rated secondary current of the transformer.

277 volts is the phase to neutral voltage on a 480V 3-phase system. There is really no such thing as 277V 2-phase. Can you convert 277/480V 3-phase utility power to 120/240V single phase? Sure, but it will be expensive for any reasonable amount of power. You will need three transformers with 480:120 ratios. The primaries are each fed 480V A-B, B-C, and C-A. The three secondaries are connected in what is called a zig-zag configuration. The output will be 120/240V. This is rarely to never done with utility power using transformers, but it is routinely done on generators to obtain single-phase power when only a 3-phase generator is available. The generator must be reconnectable, that is, the three (sometimes six)windings must not be connected internally. One drawback is you can only load such a system to 66% of its rated power. So a 60KW 3-phase generator reconnected in a zig-zag configuration can only supply 40KW of single-phase power. But at least you don't need any transformers! Look at a generator manufacturer's website (Marathon has a good one). They have technical data on these types of arrangements. So while it is theoretically possible, its not really practical unless you are talking about a generator.

isolator is a off load device which is used for isolating the downstream circuits from upstream circuits for the reason of any maintanance on downstream circuits. it is manually operated and does not contain any solenoid unlike circuit breaker. it should not be operated while it is having load. first theload on it must be made zero and then it can safely operated. its specification only rated current is given.

but circuit breaker is onload automatic device used for breaking the circuit incase of abnormal conditions like shortcircuit, overload etc., it is having three specification 1 is rated current and 2 is short circuit breaking capacity and 3 is instantaneous tripping current.