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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 could you find the purpose of a parallel circuit?
For an electrical load, such as a lamp, heater or motor, to operate at its rated power, it must be subject to its rated voltage which always corresponds to the supply voltage. For this to happen, individual loads must be connected in parallel with the supply and with each other. So all the electrical loads in your home, in your car, etc., are ALL connected in parallel.
Why the transformer is kept at a height from the ground?
If you are referring to a pole-mounted distribution transformer, it's in order to maintain a safe clearance between its high-voltage connections and ground level.
In which circuit does charge reverse direction many times per second?
In an alternating current (AC) circuit, the electric charge periodically reverses direction at a certain frequency. This is in contrast to a direct current (DC) circuit, in which charge flows in one direction only.
What is meaning of apparent power in transformer?
Apparent power is the product of voltage and current in an a.c. system, and is expressed in volt amperes. The rated apparent power of a transformer is the product of its rated secondary current and rated secondary voltage.
Why you use 0.707for rms values?
reciprocal of the square root of 2, converts from peak voltage to rms voltage
Why speed is decreased when field current increases in dc motor?
Because with more field, the armature produces the same voltage at less speed. The voltage generated by the motor must always be less than the supply voltage. A motor that is driven faster than it wants to go becomes a generator.
Why galvanometer are used in electronic instruments that measures low current and voltage?
The galvanometer is very sensitive.
What is the purpose of resonance circuit?
Resonance describes a 'condition' rather than a 'purpose', but it is made use of in (for example) radio circuits, in order to tune the radio to a particular frequency (the resonant frequency of the signal).
The rated current is the maximum current that can be drawn in normal continuous use, without any reduction in the lifetime of the device.
What are the functions of Breather Conservator and Ventpipe?
A conservator is an oil tank, located above the transformer, whose function is to ensure that the oil level remains above the transformer, while allowing it to expand and contract with temperature. The breather/vent pipe allows air to be displaced from the conservator when the level rises, and to draw back in when the oil level falls.
MCGG relay is a circuit breaker that is commonly installed in residential homes. The instruction manual can be located online on various websites and forums.
What is the formula to calculate the line to ground voltage of 480v?
If by "line" you mean a wire conductor carrying 480volts AC then there can be no "line to ground voltage" or you would have a short circuit!
Ground voltage, usually referred to as "Earth" in electrical terms, is at zero potential and thus connecting a live 480 AC line straight to Earth is extremely dangerous and unless there is a means to cut the voltage when a short occurs (in a house this will be the fuse box, these days usually containing RCB's) an electrical arc at temperatures hotter than the Sun will be produced at the point of the short, the rest of the wire will get so hot it melts and the thermal damage will spread to other wires or any combustable materials in the nearby vacinity and a raging fire could easily ensue!
There are tables giving the electrical breakdown resistance of the insulation used on electrical cables (Typically measured in kv per mm) and perhaps this may be more helpful to you.
AnswerOf course you can have a line-to-ground voltage! If the line conductor has a potential of 480 V measured with respect to ground, then there is a line-to-ground voltage of 480 V. Period! End of story! The very presence of a voltage between a line conductor and ground indicates that there is NO short circuit, as the voltage across a short circuit is zero!But to answer the question, there is no calculation involved. But you can measure it with a voltmeter.
What is current carrying for 2200kVA transformer?
Presumably you are asking about the rated secondary current of a transformer rated at 2200 kV.A?
This depends on the rated secondary voltage. You divide the rated apparent power of the transformer by the rated secondary voltage.
Of course, the actual current depends on the load.
What is the application of normally closed relay contact?
There are numerous applications for a normally-closed relay contact. It is used whenever you want to disconnect a circuit when the relay coil is energised.
How do you wire three phase into the mains?
In the UK, the term, 'mains', refers to the supply voltage provided by the distribution system. In most residential properties, the mains' supply is single phase (there are exceptions: some European countries have three-phase supplies), in which case you cannot 'wire' a three-phase load such as an induction motor into the mains.
What size generator 1200 amps?
First you need to specify what voltage you require the generator to supply...Lets Assume its 240 Volts AC. Watts=Volts x Amps so 240x1200= 28.8 Kw.
Then you have to take the efficiency of the generator into account. Mechanical power in is usually quite a bit more than the electrical power you get out...The difference is mostly the mechanical and thermal losses added together. If we say the generator is 70% efficient then you will need a generator 30% more powerful to supply a constant 1200 Amps...Thats a generator of about 38-40 Kw.
Your question reveals fundamental misunderstandings about the nature of electricity.
'Voltage' is simply another word for 'potential difference', and a potential difference appears across opposite ends of the resistor; it doesn't 'travel through' that resistor! Current, on the other hand, DOES 'travel through' the resistor and is caused by the potential difference across the resistor.
Resistance is the ratio of potential difference to current. So if the resistance remians unchanged when the current through it doubles, then it has happened because the potential difference has doubled.
What is a rotary phase converter commonly used for?
A rotary phase converter is commonly used to convert a single phase electrical power source to three phases. This allows you to use three phases instead of one.
What is the formula use for calculation voltage and current in star and delta?
Balanced Star (Wye) Connected Systems:
- Line Voltage = 1.732 x Phase Voltage
- Line Current = Phase Current
Balanced Delta Connected Systems:
- Line Voltage = Phase Voltage
- Line Current = 1.732 x Phase Current
Is oil in transformer use for lubrication?
Transformer oil is for cooling.
Transformer oil has heat conductive properties, along with its insulating properties, that take the heat build up from the windings to the outer case of the transformer. The transformer tank is used as a heat sink to allow the outside ambient temperature to cool it down. On big kVA transformers there are heat tubes on the outside of the tank. On even bigger transformers there are fins that the oil travels through. This provides a bigger surface area to dissipate the heat. The tubes and fins also allow thermal siphon of the oil through the tubes by drawing in the cooler oil at the bottom of the tank and moving it to the top of the tank where the hotter oil is. This circulation greatly increases the cooling ability of the oil to keep the transformer with in its allowable temperature rate of rise zone.
Additional AnswerThe second function of transformer oil is insulation. Oil has a far greater dielectric strength than air, so it enables internal components at different potentials to be located far closer together -thus significantly reducing the 'footprint' of a transformer.
Tap changer is a device that is used to change the secondary voltage on transformers. It is normally on the HV winding of the transformer.
Off load tap changer is designed to change the taps only when the transformer is not charged, while on load tap changer is capable of changing the tap on load too.
Why the arrow direction marked on top of the bucholz relay on power transformer?
The indicates the direction for correct installation. Bucholz relay operates when gas bubbles in the transformer oil pass through the relay in its pathway. The relay has to be installed arrow indicating upwards.
Why is armature connected to a sprinngy steel strip?
In an electric bell, a flat steel spring brings the armature back to its original position.
